Casper-Natrona Co AP Weather Records (USW00024089)
Record envelope, standing records and threshold days for Casper-Natrona Co AP (USW00024089), Wyoming, United States, with 79 years of record.
Key Facts for Casper-Natrona Co AP
- Casper-Natrona Co AP (USW00024089) is a weather station in Wyoming, United States at 42.90 latitude and -106.47 longitude, 1,621 m (5,319 ft) above sea level.
- The station reports from 1948 to 2026, 79 years of record.
- 1,464 records set at Casper-Natrona Co AP still stand.
- Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
- Casper-Natrona Co AP set a daily record high minimum temperature of 12.2 C (54.0 F) on 10 October 2026 (provisional).
Provisional Records
Records set in the last 60 days are provisional until they clear the revision window.
About the Station
- Location: Wyoming, United States, 42.90 latitude, -106.47 longitude.
- Elevation: 1,621 m (5,319 ft).
- Period of record: 1948 to 2026, 79 years.
- Eligible elements: tmax, tmin, prcp, snow, snwd.
Daily Record Envelope and 2026
32 days at or beyond a record| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 15.6 C (60.1 F) | -40.0 C (-40.0 F) | 13.9 C (57.0 F) | -23.3 C (-9.9 F) |
| Feb | 20.0 C (68.0 F) | -35.6 C (-32.1 F) | 17.8 C (64.0 F) | -28.9 C (-20.0 F) |
| Mar | 28.3 C (82.9 F) | -31.6 C (-24.9 F) | 28.3 C (82.9 F) | -15.0 C (5.0 F) |
| Apr | 28.9 C (84.0 F) | -21.1 C (-6.0 F) | 27.2 C (81.0 F) | -6.7 C (19.9 F) |
| May | 35.0 C (95.0 F) | -8.9 C (16.0 F) | 33.3 C (91.9 F) | -7.8 C (18.0 F) |
| Jun | 38.9 C (102.0 F) | -3.8 C (25.2 F) | 35.6 C (96.1 F) | -1.1 C (30.0 F) |
| Jul | 40.0 C (104.0 F) | -1.1 C (30.0 F) | 39.4 C (102.9 F) | 7.8 C (46.0 F) |
| Aug | 39.4 C (102.9 F) | -1.6 C (29.1 F) | 39.4 C (102.9 F) | 6.7 C (44.1 F) |
| Sep | 37.8 C (100.0 F) | -8.9 C (16.0 F) | 32.8 C (91.0 F) | 2.2 C (36.0 F) |
| Oct | 30.6 C (87.1 F) | -22.7 C (-8.9 F) | 30.6 C (87.1 F) | 0.6 C (33.1 F) |
| Nov | 22.8 C (73.0 F) | -32.7 C (-26.9 F) | n/a | n/a |
| Dec | 18.9 C (66.0 F) | -41.0 C (-41.8 F) | n/a | n/a |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1948 | 8 |
| 1949 | 25 |
| 1950 | 24 |
| 1951 | 18 |
| 1952 | 24 |
| 1953 | 20 |
| 1954 | 28 |
| 1955 | 21 |
| 1956 | 10 |
| 1957 | 10 |
| 1958 | 18 |
| 1959 | 16 |
| 1960 | 25 |
| 1961 | 11 |
| 1962 | 35 |
| 1963 | 15 |
| 1964 | 16 |
| 1965 | 33 |
| 1966 | 14 |
| 1967 | 14 |
| 1968 | 14 |
| 1969 | 18 |
| 1970 | 8 |
| 1971 | 13 |
| 1972 | 27 |
| 1973 | 19 |
| 1974 | 10 |
| 1975 | 19 |
| 1976 | 5 |
| 1977 | 12 |
| 1978 | 17 |
| 1979 | 12 |
| 1980 | 20 |
| 1981 | 23 |
| 1982 | 19 |
| 1983 | 25 |
| 1984 | 17 |
| 1985 | 25 |
| 1986 | 21 |
| 1987 | 18 |
| 1988 | 21 |
| 1989 | 27 |
| 1990 | 21 |
| 1991 | 13 |
| 1992 | 30 |
| 1993 | 14 |
| 1994 | 25 |
| 1995 | 22 |
| 1996 | 22 |
| 1997 | 14 |
| 1998 | 10 |
| 1999 | 16 |
| 2000 | 29 |
| 2001 | 9 |
| 2002 | 19 |
| 2003 | 23 |
| 2004 | 15 |
| 2005 | 20 |
| 2006 | 24 |
| 2007 | 11 |
| 2008 | 18 |
| 2009 | 24 |
| 2010 | 14 |
| 2011 | 7 |
| 2012 | 21 |
| 2013 | 16 |
| 2014 | 22 |
| 2015 | 21 |
| 2016 | 13 |
| 2017 | 15 |
| 2018 | 13 |
| 2019 | 14 |
| 2020 | 29 |
| 2021 | 20 |
| 2022 | 22 |
| 2023 | 12 |
| 2024 | 12 |
| 2025 | 28 |
| 2026 | 31 |
All-Time Record Progression
11 new records| Date | Kind | Detail |
|---|---|---|
| 1982-06-14 | Record daily precipitation | Record daily precipitation 54.4 mm (2.1 in) |
| 1982-12-24 | Record daily snowfall | Record daily snowfall 61.7 cm (24.3 in) |
| 1982-12-24 | Record snow depth | Record snow depth 53.3 cm (21.0 in) |
| 1986-06-19 | Record daily precipitation | Record daily precipitation 54.6 mm (2.1 in) |
| 1989-02-02 | Record low maximum temperature | Record low maximum temperature -29.4 C (-20.9 F) |
| 1989-02-03 | Record low maximum temperature | Record low maximum temperature -31.7 C (-25.1 F) |
| 1990-12-21 | Record low minimum temperature | Record low minimum temperature -40.6 C (-41.1 F) |
| 2000-05-17 | Record daily precipitation | Record daily precipitation 56.4 mm (2.2 in) |
| 2006-07-18 | Record high minimum temperature | Record high minimum temperature 23.3 C (73.9 F) |
| 2022-12-22 | Record low minimum temperature | Record low minimum temperature -41.0 C (-41.8 F) |
| 2023-04-03 | Record daily snowfall | Record daily snowfall 67.8 cm (26.7 in) |
Wettest Day of Each Month
May: 56.4 mm (2.2 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 14.0 mm (0.6 in) | 11 January 2023 |
| Feb | 15.0 mm (0.6 in) | 14 February 1995 |
| Mar | 27.4 mm (1.1 in) | 31 March 2017 |
| Apr | 46.2 mm (1.8 in) | 20 April 1974 |
| May | 56.4 mm (2.2 in) | 17 May 2000 |
| Jun | 54.6 mm (2.1 in) | 19 June 1986 |
| Jul | 45.2 mm (1.8 in) | 22 July 1983 |
| Aug | 56.1 mm (2.2 in) | 2 August 2007 |
| Sep | 51.1 mm (2.0 in) | 20 September 1989 |
| Oct | 52.3 mm (2.1 in) | 16 October 1998 |
| Nov | 25.1 mm (1.0 in) | 2 November 1994 |
| Dec | 32.0 mm (1.3 in) | 24 December 1982 |
Period of Record Coverage
1948 to 2026| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1948 | 153 | 42% | No |
| 1949 | 365 | 100% | Yes |
| 1950 | 365 | 100% | Yes |
| 1951 | 365 | 100% | Yes |
| 1952 | 366 | 100% | Yes |
| 1953 | 365 | 100% | Yes |
| 1954 | 365 | 100% | Yes |
| 1955 | 365 | 100% | Yes |
| 1956 | 366 | 100% | Yes |
| 1957 | 365 | 100% | Yes |
| 1958 | 365 | 100% | Yes |
| 1959 | 365 | 100% | Yes |
| 1960 | 366 | 100% | Yes |
| 1961 | 365 | 100% | Yes |
| 1962 | 365 | 100% | Yes |
| 1963 | 365 | 100% | Yes |
| 1964 | 366 | 100% | Yes |
| 1965 | 365 | 100% | Yes |
| 1966 | 365 | 100% | Yes |
| 1967 | 365 | 100% | Yes |
| 1968 | 366 | 100% | Yes |
| 1969 | 365 | 100% | Yes |
| 1970 | 365 | 100% | Yes |
| 1971 | 365 | 100% | Yes |
| 1972 | 366 | 100% | Yes |
| 1973 | 365 | 100% | Yes |
| 1974 | 365 | 100% | Yes |
| 1975 | 365 | 100% | Yes |
| 1976 | 366 | 100% | Yes |
| 1977 | 365 | 100% | Yes |
| 1978 | 365 | 100% | Yes |
| 1979 | 365 | 100% | Yes |
| 1980 | 366 | 100% | Yes |
| 1981 | 365 | 100% | Yes |
| 1982 | 365 | 100% | Yes |
| 1983 | 365 | 100% | Yes |
| 1984 | 366 | 100% | Yes |
| 1985 | 365 | 100% | Yes |
| 1986 | 365 | 100% | Yes |
| 1987 | 365 | 100% | Yes |
| 1988 | 366 | 100% | Yes |
| 1989 | 364 | 100% | Yes |
| 1990 | 365 | 100% | Yes |
| 1991 | 365 | 100% | Yes |
| 1992 | 366 | 100% | Yes |
| 1993 | 365 | 100% | Yes |
| 1994 | 365 | 100% | Yes |
| 1995 | 365 | 100% | Yes |
| 1996 | 366 | 100% | Yes |
| 1997 | 365 | 100% | Yes |
| 1998 | 365 | 100% | Yes |
| 1999 | 365 | 100% | Yes |
| 2000 | 366 | 100% | Yes |
| 2001 | 365 | 100% | Yes |
| 2002 | 365 | 100% | Yes |
| 2003 | 365 | 100% | Yes |
| 2004 | 366 | 100% | Yes |
| 2005 | 365 | 100% | Yes |
| 2006 | 365 | 100% | Yes |
| 2007 | 365 | 100% | Yes |
| 2008 | 366 | 100% | Yes |
| 2009 | 365 | 100% | Yes |
| 2010 | 365 | 100% | Yes |
| 2011 | 364 | 100% | Yes |
| 2012 | 366 | 100% | Yes |
| 2013 | 365 | 100% | Yes |
| 2014 | 365 | 100% | Yes |
| 2015 | 365 | 100% | Yes |
| 2016 | 366 | 100% | Yes |
| 2017 | 365 | 100% | Yes |
| 2018 | 365 | 100% | Yes |
| 2019 | 365 | 100% | Yes |
| 2020 | 366 | 100% | Yes |
| 2021 | 365 | 100% | Yes |
| 2022 | 365 | 100% | Yes |
| 2023 | 364 | 100% | Yes |
| 2024 | 366 | 100% | Yes |
| 2025 | 365 | 100% | Yes |
| 2026 | 285 | 78% | No |
Latest Records
20| Date | Station | Record | Value | Beat old record by | Old record stood | Significance |
|---|---|---|---|---|---|---|
| 10 October 2026 | Casper-Natrona Co AP, US | daily high min (Provisional) | 12.2 C (54.0 F) | 2.2 C (4.0 F) | 64 years | 30 of 100 (Routine) |
| 8 October 2026 | Casper-Natrona Co AP, US | daily high max (Provisional) | 27.8 C (82.0 F) | 0.6 C (1.1 F) | 5 years | 8 of 100 (Routine) |
| 6 October 2026 | Casper-Natrona Co AP, US | daily high max (Provisional) | 30.0 C (86.0 F) | 1.1 C (2.0 F) | 51 years | 23 of 100 (Routine) |
| 5 October 2026 | Casper-Natrona Co AP, US | monthly high max (Tie, Provisional) | 30.6 C (87.1 F) | tie | 34 years | 6 of 100 (Routine) |
| 21 August 2026 | Casper-Natrona Co AP, US | daily high max (Provisional) | 37.2 C (99.0 F) | 1.6 C (2.9 F) | 1 year | 10 of 100 (Routine) |
| 15 August 2026 | Casper-Natrona Co AP, US | daily rain | 14.7 mm (0.6 in) | 3.0 mm (0.12 in) | 16 years | 17 of 100 (Routine) |
| 13 August 2026 | Casper-Natrona Co AP, US | daily rain | 32.0 mm (1.3 in) | 15.7 mm (0.6 in) | 36 years | 47 of 100 (Notable) |
| 8 August 2026 | Casper-Natrona Co AP, US | daily high max | 37.2 C (99.0 F) | 0.5 C (0.9 F) | 43 years | 20 of 100 (Routine) |
| 2 August 2026 | Casper-Natrona Co AP, US | monthly high max | 39.4 C (102.9 F) | 0.5 C (0.9 F) | 46 years | 32 of 100 (Routine) |
| 1 August 2026 | Casper-Natrona Co AP, US | daily high max (Tie) | 37.2 C (99.0 F) | tie | 17 years | 3 of 100 (Routine) |
| 26 July 2026 | Casper-Natrona Co AP, US | daily high max | 38.9 C (102.0 F) | 2.2 C (4.0 F) | 17 years | 17 of 100 (Routine) |
| 25 July 2026 | Casper-Natrona Co AP, US | daily high min | 20.6 C (69.1 F) | 2.3 C (4.1 F) | 64 years | 33 of 100 (Routine) |
| 25 July 2026 | Casper-Natrona Co AP, US | daily high max | 38.9 C (102.0 F) | 1.1 C (2.0 F) | 1 year | 9 of 100 (Routine) |
| 21 July 2026 | Casper-Natrona Co AP, US | daily high min (Tie) | 19.4 C (66.9 F) | tie | 19 years | 3 of 100 (Routine) |
| 20 July 2026 | Casper-Natrona Co AP, US | daily high max (Tie) | 37.2 C (99.0 F) | tie | 20 years | 3 of 100 (Routine) |
| 15 June 2026 | Casper-Natrona Co AP, US | daily low min | -1.1 C (30.0 F) | 3.3 C (5.9 F) | 49 years | 30 of 100 (Routine) |
| 6 June 2026 | Casper-Natrona Co AP, US | daily high max | 35.6 C (96.1 F) | 1.2 C (2.2 F) | 20 years | 15 of 100 (Routine) |
| 19 May 2026 | Casper-Natrona Co AP, US | daily low min | -3.3 C (26.1 F) | 0.5 C (0.9 F) | 60 years | 26 of 100 (Routine) |
| 18 May 2026 | Casper-Natrona Co AP, US | daily low max | 3.3 C (37.9 F) | 2.3 C (4.1 F) | 48 years | 24 of 100 (Routine) |
| 18 May 2026 | Casper-Natrona Co AP, US | daily snow depth (Tie) | 5.1 cm (2.0 in) | tie | 48 years | 5 of 100 (Routine) |
Climate Trend
77 complete years, 1949 to 2025| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1949 | 6.6 C | -0.97 C |
| 1950 | 7.0 C | -0.52 C |
| 1951 | 6.2 C | -1.36 C |
| 1952 | 8.0 C | +0.42 C |
| 1953 | 8.5 C | +0.96 C |
| 1954 | 9.1 C | +1.52 C |
| 1955 | 7.1 C | -0.43 C |
| 1956 | 8.0 C | +0.44 C |
| 1957 | 7.3 C | -0.25 C |
| 1958 | 8.2 C | +0.66 C |
| 1959 | 7.2 C | -0.33 C |
| 1960 | 7.3 C | -0.25 C |
| 1961 | 7.6 C | +0.10 C |
| 1962 | 7.7 C | +0.16 C |
| 1963 | 8.5 C | +0.96 C |
| 1964 | 6.4 C | -1.14 C |
| 1965 | 6.9 C | -0.67 C |
| 1966 | 7.6 C | +0.10 C |
| 1967 | 7.1 C | -0.45 C |
| 1968 | 6.6 C | -0.95 C |
| 1969 | 7.7 C | +0.20 C |
| 1970 | 7.1 C | -0.45 C |
| 1971 | 6.6 C | -0.94 C |
| 1972 | 6.6 C | -0.89 C |
| 1973 | 6.7 C | -0.81 C |
| 1974 | 7.2 C | -0.31 C |
| 1975 | 6.5 C | -1.07 C |
| 1976 | 7.7 C | +0.16 C |
| 1977 | 8.1 C | +0.53 C |
| 1978 | 6.2 C | -1.29 C |
| 1979 | 6.6 C | -0.96 C |
| 1980 | 7.6 C | +0.05 C |
| 1981 | 8.9 C | +1.39 C |
| 1982 | 7.1 C | -0.46 C |
| 1983 | 7.4 C | -0.14 C |
| 1984 | 6.8 C | -0.74 C |
| 1985 | 5.8 C | -1.72 C |
| 1986 | 8.3 C | +0.76 C |
| 1987 | 8.0 C | +0.48 C |
| 1988 | 8.3 C | +0.78 C |
| 1989 | 7.3 C | -0.20 C |
| 1990 | 7.8 C | +0.25 C |
| 1991 | 8.1 C | +0.58 C |
| 1992 | 8.9 C | +1.33 C |
| 1993 | 7.1 C | -0.40 C |
| 1994 | 9.5 C | +1.95 C |
| 1995 | 7.8 C | +0.26 C |
| 1996 | 6.9 C | -0.60 C |
| 1997 | 6.8 C | -0.71 C |
| 1998 | 8.0 C | +0.45 C |
| 1999 | 8.4 C | +0.85 C |
| 2000 | 7.6 C | +0.03 C |
| 2001 | 8.3 C | +0.75 C |
| 2002 | 6.9 C | -0.62 C |
| 2003 | 7.9 C | +0.41 C |
| 2004 | 7.7 C | +0.19 C |
| 2005 | 8.2 C | +0.70 C |
| 2006 | 8.4 C | +0.83 C |
| 2007 | 8.0 C | +0.48 C |
| 2008 | 6.7 C | -0.83 C |
| 2009 | 6.5 C | -0.99 C |
| 2010 | 7.5 C | -0.07 C |
| 2011 | 7.3 C | -0.27 C |
| 2012 | 9.2 C | +1.71 C |
| 2013 | 7.3 C | -0.26 C |
| 2014 | 7.2 C | -0.35 C |
| 2015 | 8.4 C | +0.91 C |
| 2016 | 8.2 C | +0.65 C |
| 2017 | 7.9 C | +0.36 C |
| 2018 | 7.5 C | -0.03 C |
| 2019 | 6.5 C | -1.06 C |
| 2020 | 7.6 C | +0.09 C |
| 2021 | 8.0 C | +0.44 C |
| 2022 | 6.9 C | -0.60 C |
| 2023 | 7.1 C | -0.48 C |
| 2024 | 8.7 C | +1.17 C |
| 2025 | 8.4 C | +0.89 C |
The fitted trend in annual mean temperature here over 1949 to 2025 is 0.07 C (-0.01 to 0.14) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.12 F (-0.02 to 0.26) per decade. The slope is a straight line fitted to 77 complete years; the brackets give its 95 percent interval.
| Measure | Per decade (C) | Per decade (F) | Period | Complete years | Reading |
|---|---|---|---|---|---|
| Annual mean temperature | 0.07 C (-0.01 to 0.14) per decade | 0.12 F (-0.02 to 0.26) per decade | 1949 to 2025 | 77 | Not clearly different from zero |
| Mean daily maximum | 0.2 C (0.1 to 0.3) per decade | 0.3 F (0.2 to 0.5) per decade | 1949 to 2025 | 77 | Rise |
| Mean daily minimum | -0.06 C (-0.13 to 0.02) per decade | -0.10 F (-0.24 to 0.04) per decade | 1949 to 2025 | 77 | Not clearly different from zero |
A year is complete when all 12 months have at least 20 days of both daily maximum and daily minimum readings. The annual mean is the mean of the monthly means. The trend describes this one station over this period; it does not say what caused the change.
Extremes by Year
1948 to 2026| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 40.0 C (104.0 F) | 1954 | 37.2 C (99.0 F) | 79 |
| Coldest night (TNn) | -41.0 C (-41.8 F) | 2022 | -30.0 C (-22.0 F) | 79 |
| Wettest day (Rx1day) | 56.4 mm (2.2 in) | 2000 | 24.4 mm (1.0 in) | 79 |
| Wettest five days (Rx5day) | 90.4 mm (3.6 in) | 1978 | 42.7 mm (1.7 in) | 79 |
| Longest dry spell (CDD) | 91 days | 2020 | 31 days | 79 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1948 | 35.6 C (96.1 F) |
| 1949 | 36.7 C (98.1 F) |
| 1950 | 33.9 C (93.0 F) |
| 1951 | 36.1 C (97.0 F) |
| 1952 | 37.2 C (99.0 F) |
| 1953 | 37.8 C (100.0 F) |
| 1954 | 40.0 C (104.0 F) |
| 1955 | 35.6 C (96.1 F) |
| 1956 | 35.0 C (95.0 F) |
| 1957 | 35.0 C (95.0 F) |
| 1958 | 35.6 C (96.1 F) |
| 1959 | 37.8 C (100.0 F) |
| 1960 | 35.6 C (96.1 F) |
| 1961 | 35.6 C (96.1 F) |
| 1962 | 34.4 C (93.9 F) |
| 1963 | 35.6 C (96.1 F) |
| 1964 | 35.0 C (95.0 F) |
| 1965 | 35.6 C (96.1 F) |
| 1966 | 37.2 C (99.0 F) |
| 1967 | 35.0 C (95.0 F) |
| 1968 | 35.0 C (95.0 F) |
| 1969 | 37.2 C (99.0 F) |
| 1970 | 38.3 C (100.9 F) |
| 1971 | 35.6 C (96.1 F) |
| 1972 | 36.7 C (98.1 F) |
| 1973 | 37.2 C (99.0 F) |
| 1974 | 35.0 C (95.0 F) |
| 1975 | 35.0 C (95.0 F) |
| 1976 | 37.2 C (99.0 F) |
| 1977 | 37.2 C (99.0 F) |
| 1978 | 36.1 C (97.0 F) |
| 1979 | 38.9 C (102.0 F) |
| 1980 | 36.7 C (98.1 F) |
| 1981 | 38.3 C (100.9 F) |
| 1982 | 37.8 C (100.0 F) |
| 1983 | 38.3 C (100.9 F) |
| 1984 | 35.6 C (96.1 F) |
| 1985 | 36.7 C (98.1 F) |
| 1986 | 37.2 C (99.0 F) |
| 1987 | 36.1 C (97.0 F) |
| 1988 | 38.9 C (102.0 F) |
| 1989 | 38.9 C (102.0 F) |
| 1990 | 38.9 C (102.0 F) |
| 1991 | 37.2 C (99.0 F) |
| 1992 | 37.2 C (99.0 F) |
| 1993 | 37.2 C (99.0 F) |
| 1994 | 38.3 C (100.9 F) |
| 1995 | 38.3 C (100.9 F) |
| 1996 | 37.2 C (99.0 F) |
| 1997 | 36.7 C (98.1 F) |
| 1998 | 39.4 C (102.9 F) |
| 1999 | 37.2 C (99.0 F) |
| 2000 | 37.8 C (100.0 F) |
| 2001 | 38.3 C (100.9 F) |
| 2002 | 37.8 C (100.0 F) |
| 2003 | 37.8 C (100.0 F) |
| 2004 | 35.6 C (96.1 F) |
| 2005 | 40.0 C (104.0 F) |
| 2006 | 40.0 C (104.0 F) |
| 2007 | 37.8 C (100.0 F) |
| 2008 | 37.2 C (99.0 F) |
| 2009 | 36.1 C (97.0 F) |
| 2010 | 36.7 C (98.1 F) |
| 2011 | 36.7 C (98.1 F) |
| 2012 | 37.8 C (100.0 F) |
| 2013 | 36.7 C (98.1 F) |
| 2014 | 37.8 C (100.0 F) |
| 2015 | 36.1 C (97.0 F) |
| 2016 | 37.8 C (100.0 F) |
| 2017 | 36.7 C (98.1 F) |
| 2018 | 37.8 C (100.0 F) |
| 2019 | 36.7 C (98.1 F) |
| 2020 | 37.8 C (100.0 F) |
| 2021 | 38.3 C (100.9 F) |
| 2022 | 38.3 C (100.9 F) |
| 2023 | 38.3 C (100.9 F) |
| 2024 | 37.8 C (100.0 F) |
| 2025 | 37.8 C (100.0 F) |
| 2026 | 39.4 C (102.9 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1948 | -20.0 C (-4.0 F) |
| 1949 | -40.0 C (-40.0 F) |
| 1950 | -32.2 C (-26.0 F) |
| 1951 | -30.6 C (-23.1 F) |
| 1952 | -27.2 C (-17.0 F) |
| 1953 | -21.1 C (-6.0 F) |
| 1954 | -23.9 C (-11.0 F) |
| 1955 | -26.1 C (-15.0 F) |
| 1956 | -25.0 C (-13.0 F) |
| 1957 | -30.0 C (-22.0 F) |
| 1958 | -22.8 C (-9.0 F) |
| 1959 | -31.7 C (-25.1 F) |
| 1960 | -28.3 C (-18.9 F) |
| 1961 | -27.8 C (-18.0 F) |
| 1962 | -34.4 C (-29.9 F) |
| 1963 | -32.8 C (-27.0 F) |
| 1964 | -35.0 C (-31.0 F) |
| 1965 | -29.4 C (-20.9 F) |
| 1966 | -26.7 C (-16.1 F) |
| 1967 | -28.3 C (-18.9 F) |
| 1968 | -33.3 C (-27.9 F) |
| 1969 | -22.8 C (-9.0 F) |
| 1970 | -30.6 C (-23.1 F) |
| 1971 | -26.7 C (-16.1 F) |
| 1972 | -40.0 C (-40.0 F) |
| 1973 | -31.1 C (-24.0 F) |
| 1974 | -33.3 C (-27.9 F) |
| 1975 | -26.7 C (-16.1 F) |
| 1976 | -25.6 C (-14.1 F) |
| 1977 | -30.6 C (-23.1 F) |
| 1978 | -36.7 C (-34.1 F) |
| 1979 | -33.9 C (-29.0 F) |
| 1980 | -35.6 C (-32.1 F) |
| 1981 | -28.3 C (-18.9 F) |
| 1982 | -32.8 C (-27.0 F) |
| 1983 | -39.4 C (-38.9 F) |
| 1984 | -29.4 C (-20.9 F) |
| 1985 | -32.2 C (-26.0 F) |
| 1986 | -27.8 C (-18.0 F) |
| 1987 | -24.4 C (-11.9 F) |
| 1988 | -22.2 C (-8.0 F) |
| 1989 | -33.9 C (-29.0 F) |
| 1990 | -40.6 C (-41.1 F) |
| 1991 | -27.8 C (-18.0 F) |
| 1992 | -28.9 C (-20.0 F) |
| 1993 | -30.6 C (-23.1 F) |
| 1994 | -25.0 C (-13.0 F) |
| 1995 | -22.8 C (-9.0 F) |
| 1996 | -32.8 C (-27.0 F) |
| 1997 | -28.3 C (-18.9 F) |
| 1998 | -31.7 C (-25.1 F) |
| 1999 | -22.8 C (-9.0 F) |
| 2000 | -28.3 C (-18.9 F) |
| 2001 | -26.7 C (-16.1 F) |
| 2002 | -25.0 C (-13.0 F) |
| 2003 | -34.4 C (-29.9 F) |
| 2004 | -25.6 C (-14.1 F) |
| 2005 | -30.6 C (-23.1 F) |
| 2006 | -35.6 C (-32.1 F) |
| 2007 | -28.9 C (-20.0 F) |
| 2008 | -28.9 C (-20.0 F) |
| 2009 | -33.9 C (-29.0 F) |
| 2010 | -32.8 C (-27.0 F) |
| 2011 | -31.1 C (-24.0 F) |
| 2012 | -23.9 C (-11.0 F) |
| 2013 | -29.9 C (-21.8 F) |
| 2014 | -32.7 C (-26.9 F) |
| 2015 | -28.8 C (-19.8 F) |
| 2016 | -36.0 C (-32.8 F) |
| 2017 | -33.2 C (-27.8 F) |
| 2018 | -29.3 C (-20.7 F) |
| 2019 | -30.5 C (-22.9 F) |
| 2020 | -22.7 C (-8.9 F) |
| 2021 | -31.0 C (-23.8 F) |
| 2022 | -41.0 C (-41.8 F) |
| 2023 | -32.1 C (-25.8 F) |
| 2024 | -38.2 C (-36.8 F) |
| 2025 | -31.6 C (-24.9 F) |
| 2026 | -28.9 C (-20.0 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1948 | 15.0 mm (0.6 in) |
| 1949 | 21.1 mm (0.8 in) |
| 1950 | 44.7 mm (1.8 in) |
| 1951 | 33.8 mm (1.3 in) |
| 1952 | 52.6 mm (2.1 in) |
| 1953 | 21.8 mm (0.9 in) |
| 1954 | 24.1 mm (0.9 in) |
| 1955 | 14.0 mm (0.6 in) |
| 1956 | 13.5 mm (0.5 in) |
| 1957 | 18.8 mm (0.7 in) |
| 1958 | 24.9 mm (1.0 in) |
| 1959 | 23.9 mm (0.9 in) |
| 1960 | 14.5 mm (0.6 in) |
| 1961 | 20.1 mm (0.8 in) |
| 1962 | 48.3 mm (1.9 in) |
| 1963 | 17.3 mm (0.7 in) |
| 1964 | 39.9 mm (1.6 in) |
| 1965 | 21.3 mm (0.8 in) |
| 1966 | 14.5 mm (0.6 in) |
| 1967 | 21.1 mm (0.8 in) |
| 1968 | 17.3 mm (0.7 in) |
| 1969 | 31.0 mm (1.2 in) |
| 1970 | 26.9 mm (1.1 in) |
| 1971 | 35.3 mm (1.4 in) |
| 1972 | 20.3 mm (0.8 in) |
| 1973 | 37.1 mm (1.5 in) |
| 1974 | 46.2 mm (1.8 in) |
| 1975 | 22.9 mm (0.9 in) |
| 1976 | 21.3 mm (0.8 in) |
| 1977 | 29.0 mm (1.1 in) |
| 1978 | 49.8 mm (2.0 in) |
| 1979 | 34.3 mm (1.4 in) |
| 1980 | 24.6 mm (1.0 in) |
| 1981 | 18.5 mm (0.7 in) |
| 1982 | 54.4 mm (2.1 in) |
| 1983 | 45.2 mm (1.8 in) |
| 1984 | 30.0 mm (1.2 in) |
| 1985 | 21.3 mm (0.8 in) |
| 1986 | 54.6 mm (2.1 in) |
| 1987 | 26.9 mm (1.1 in) |
| 1988 | 13.0 mm (0.5 in) |
| 1989 | 51.1 mm (2.0 in) |
| 1990 | 21.3 mm (0.8 in) |
| 1991 | 38.6 mm (1.5 in) |
| 1992 | 14.2 mm (0.6 in) |
| 1993 | 44.2 mm (1.7 in) |
| 1994 | 33.5 mm (1.3 in) |
| 1995 | 42.2 mm (1.7 in) |
| 1996 | 15.2 mm (0.6 in) |
| 1997 | 24.4 mm (1.0 in) |
| 1998 | 52.3 mm (2.1 in) |
| 1999 | 18.0 mm (0.7 in) |
| 2000 | 56.4 mm (2.2 in) |
| 2001 | 10.4 mm (0.4 in) |
| 2002 | 14.0 mm (0.6 in) |
| 2003 | 53.8 mm (2.1 in) |
| 2004 | 41.7 mm (1.6 in) |
| 2005 | 27.7 mm (1.1 in) |
| 2006 | 19.8 mm (0.8 in) |
| 2007 | 56.1 mm (2.2 in) |
| 2008 | 24.1 mm (0.9 in) |
| 2009 | 40.9 mm (1.6 in) |
| 2010 | 21.6 mm (0.9 in) |
| 2011 | 19.1 mm (0.8 in) |
| 2012 | 15.7 mm (0.6 in) |
| 2013 | 39.1 mm (1.5 in) |
| 2014 | 19.6 mm (0.8 in) |
| 2015 | 18.5 mm (0.7 in) |
| 2016 | 38.1 mm (1.5 in) |
| 2017 | 27.4 mm (1.1 in) |
| 2018 | 20.8 mm (0.8 in) |
| 2019 | 24.4 mm (1.0 in) |
| 2020 | 10.7 mm (0.4 in) |
| 2021 | 30.7 mm (1.2 in) |
| 2022 | 24.4 mm (1.0 in) |
| 2023 | 34.0 mm (1.3 in) |
| 2024 | 21.6 mm (0.9 in) |
| 2025 | 31.5 mm (1.2 in) |
| 2026 | 32.0 mm (1.3 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1948 | 20.8 mm (0.8 in) |
| 1949 | 39.9 mm (1.6 in) |
| 1950 | 47.8 mm (1.9 in) |
| 1951 | 35.6 mm (1.4 in) |
| 1952 | 58.0 mm (2.3 in) |
| 1953 | 25.9 mm (1.0 in) |
| 1954 | 29.4 mm (1.2 in) |
| 1955 | 23.7 mm (0.9 in) |
| 1956 | 26.7 mm (1.1 in) |
| 1957 | 42.7 mm (1.7 in) |
| 1958 | 26.5 mm (1.0 in) |
| 1959 | 42.2 mm (1.7 in) |
| 1960 | 16.3 mm (0.6 in) |
| 1961 | 30.2 mm (1.2 in) |
| 1962 | 63.3 mm (2.5 in) |
| 1963 | 25.4 mm (1.0 in) |
| 1964 | 43.4 mm (1.7 in) |
| 1965 | 38.9 mm (1.5 in) |
| 1966 | 20.5 mm (0.8 in) |
| 1967 | 42.7 mm (1.7 in) |
| 1968 | 56.1 mm (2.2 in) |
| 1969 | 50.6 mm (2.0 in) |
| 1970 | 47.2 mm (1.9 in) |
| 1971 | 62.5 mm (2.5 in) |
| 1972 | 23.1 mm (0.9 in) |
| 1973 | 53.1 mm (2.1 in) |
| 1974 | 85.3 mm (3.4 in) |
| 1975 | 54.4 mm (2.1 in) |
| 1976 | 45.7 mm (1.8 in) |
| 1977 | 44.3 mm (1.7 in) |
| 1978 | 90.4 mm (3.6 in) |
| 1979 | 53.7 mm (2.1 in) |
| 1980 | 51.8 mm (2.0 in) |
| 1981 | 36.1 mm (1.4 in) |
| 1982 | 64.7 mm (2.5 in) |
| 1983 | 63.7 mm (2.5 in) |
| 1984 | 32.8 mm (1.3 in) |
| 1985 | 29.2 mm (1.1 in) |
| 1986 | 54.9 mm (2.2 in) |
| 1987 | 33.3 mm (1.3 in) |
| 1988 | 15.5 mm (0.6 in) |
| 1989 | 55.0 mm (2.2 in) |
| 1990 | 26.4 mm (1.0 in) |
| 1991 | 61.7 mm (2.4 in) |
| 1992 | 24.6 mm (1.0 in) |
| 1993 | 49.8 mm (2.0 in) |
| 1994 | 55.4 mm (2.2 in) |
| 1995 | 75.2 mm (3.0 in) |
| 1996 | 27.7 mm (1.1 in) |
| 1997 | 30.5 mm (1.2 in) |
| 1998 | 60.2 mm (2.4 in) |
| 1999 | 24.6 mm (1.0 in) |
| 2000 | 58.5 mm (2.3 in) |
| 2001 | 19.1 mm (0.8 in) |
| 2002 | 25.0 mm (1.0 in) |
| 2003 | 57.6 mm (2.3 in) |
| 2004 | 45.2 mm (1.8 in) |
| 2005 | 34.2 mm (1.3 in) |
| 2006 | 22.9 mm (0.9 in) |
| 2007 | 77.1 mm (3.0 in) |
| 2008 | 70.1 mm (2.8 in) |
| 2009 | 61.2 mm (2.4 in) |
| 2010 | 45.5 mm (1.8 in) |
| 2011 | 31.3 mm (1.2 in) |
| 2012 | 26.5 mm (1.0 in) |
| 2013 | 54.8 mm (2.2 in) |
| 2014 | 25.7 mm (1.0 in) |
| 2015 | 37.3 mm (1.5 in) |
| 2016 | 75.4 mm (3.0 in) |
| 2017 | 39.9 mm (1.6 in) |
| 2018 | 32.8 mm (1.3 in) |
| 2019 | 39.1 mm (1.5 in) |
| 2020 | 13.7 mm (0.5 in) |
| 2021 | 47.5 mm (1.9 in) |
| 2022 | 43.7 mm (1.7 in) |
| 2023 | 42.6 mm (1.7 in) |
| 2024 | 26.7 mm (1.1 in) |
| 2025 | 53.3 mm (2.1 in) |
| 2026 | 47.0 mm (1.9 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1948 | 18 days |
| 1949 | 41 days |
| 1950 | 45 days |
| 1951 | 28 days |
| 1952 | 39 days |
| 1953 | 33 days |
| 1954 | 29 days |
| 1955 | 28 days |
| 1956 | 65 days |
| 1957 | 22 days |
| 1958 | 43 days |
| 1959 | 33 days |
| 1960 | 35 days |
| 1961 | 50 days |
| 1962 | 39 days |
| 1963 | 38 days |
| 1964 | 30 days |
| 1965 | 55 days |
| 1966 | 29 days |
| 1967 | 18 days |
| 1968 | 28 days |
| 1969 | 37 days |
| 1970 | 31 days |
| 1971 | 37 days |
| 1972 | 23 days |
| 1973 | 28 days |
| 1974 | 21 days |
| 1975 | 35 days |
| 1976 | 30 days |
| 1977 | 36 days |
| 1978 | 34 days |
| 1979 | 34 days |
| 1980 | 32 days |
| 1981 | 44 days |
| 1982 | 23 days |
| 1983 | 24 days |
| 1984 | 17 days |
| 1985 | 23 days |
| 1986 | 23 days |
| 1987 | 26 days |
| 1988 | 36 days |
| 1989 | 31 days |
| 1990 | 31 days |
| 1991 | 26 days |
| 1992 | 38 days |
| 1993 | 25 days |
| 1994 | 22 days |
| 1995 | 25 days |
| 1996 | 22 days |
| 1997 | 21 days |
| 1998 | 41 days |
| 1999 | 39 days |
| 2000 | 29 days |
| 2001 | 37 days |
| 2002 | 31 days |
| 2003 | 41 days |
| 2004 | 34 days |
| 2005 | 35 days |
| 2006 | 37 days |
| 2007 | 39 days |
| 2008 | 23 days |
| 2009 | 27 days |
| 2010 | 30 days |
| 2011 | 27 days |
| 2012 | 26 days |
| 2013 | 30 days |
| 2014 | 28 days |
| 2015 | 29 days |
| 2016 | 30 days |
| 2017 | 22 days |
| 2018 | 34 days |
| 2019 | 37 days |
| 2020 | 91 days |
| 2021 | 29 days |
| 2022 | 34 days |
| 2023 | 37 days |
| 2024 | 35 days |
| 2025 | 31 days |
| 2026 | 47 days |
Each chart shows one value per year; the dot marks the record year. TXx is the hottest daily maximum, TNn the coldest daily minimum, Rx1day and Rx5day the largest one-day and five-day rain totals, and CDD the longest run of days with less than 1 mm of rain. A year with missing days can understate an extreme.
Frost Dates and Growing Season
77 years with a frostAcross 77 years with a frost, the median last spring frost at Casper-Natrona Co AP falls on 21 May and the median first autumn frost on 20 September, which leaves a median of 120 days between them.
In 1996 to 2025 the median growing season was 117 days. That is 2 days fewer than in 1949 to 1978.
Fitted over all years, the growing season changes by -1.9 days per decade at this station.
| Measure | Median, all years | Earliest period (1949 to 1978) | Recent period (1996 to 2025) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 21 May | 20 May | 26 May | 6 days later | +1.1 days per decade |
| First autumn frost | 20 September | 21 September | 21 September | no change | -0.8 days per decade |
| Growing days | 120 days | 119 days | 117 days | 2 days fewer | -1.9 days per decade |
A frost day is a day with a daily minimum at or below 0 C (32 F). The last spring frost and the first autumn frost are the last and first such days of the cold season, and growing days are the days between them. A negative trend for the last spring frost means it comes earlier.
Rainfall Return Levels
77 years, 1949 to 2025A day with at least 26.8 mm (1.1 in) of rain is expected about once in 2 years. A day with at least 72.9 mm (2.9 in) of rain is expected about once in 100 years.
| Expected about once in | A day with at least | Note |
|---|---|---|
| 2 years | 26.8 mm (1.1 in) | |
| 5 years | 38.6 mm (1.5 in) | |
| 10 years | 46.6 mm (1.8 in) | |
| 25 years | 57.0 mm (2.2 in) | |
| 50 years | 64.9 mm (2.6 in) | |
| 100 years | 72.9 mm (2.9 in) | Longer than the 77 years of record |
The levels come from a generalised extreme value (GEV) distribution fitted by L-moments to the wettest-day total of each year, 77 years of values from 1949 to 2025.
A return level is an estimate. It is least reliable for the long periods, 50 and 100 years, and for any period longer than the record behind the fit, where the fit has to reach past the largest day actually observed. It is not a forecast.
The largest wettest-day totals in the fit: 56.4 mm (2.2 in) in 2000; 56.1 mm (2.2 in) in 2007; 54.6 mm (2.1 in) in 1986.
Station Changes
2 suspected2 changes were suspected in the annual mean temperature of Casper-Natrona Co AP, at 1991 and 1997. Each is measured against neighbouring stations.
- Relative to 5 neighbouring stations, the station's annual mean temperature from 1991 ran 0.6 C (1.1 F) higher than in the years before (likely change).
- Relative to 5 neighbouring stations, the station's annual mean temperature from 1997 ran 0.8 C (1.5 F) lower than in the years before (likely change).
| Year | Shift (C) | Shift (F) | Strength | Neighbours |
|---|---|---|---|---|
| 1991 | +0.6 | +1.1 | likely | 5 |
| 1997 | -0.8 | -1.5 | likely | 5 |
Possible change at the station (a move, a new instrument or a new site); the record is kept as measured. A "likely" change has a larger test statistic than a "possible" one. Neither says why the station differs from its neighbours. How changes are found, and the largest ones.
Climate Twins
2011 to 2025 against 1961 to 1990Over 2011 to 2025, Casper-Natrona Co AP had a mean temperature of 7.7 C (45.9 F) and 321.4 mm (12.7 in) of rain a year. The 3 stations whose 1961 to 1990 climate was closest to that are Black Mtn (United States, 133 km away), Sybille Rsch Unit (United States, 155 km away) and Buffalo (United States, 162 km away).
| Twin station | Country | Distance away | Mean temperature, 1961-1990 | Rain a year, 1961-1990 | Climate difference |
|---|---|---|---|---|---|
| Black Mtn | United States | 133 km (83 mi) | 7.4 C (45.2 F) | 337.9 mm (13.3 in) | 0.97 |
| Sybille Rsch Unit | United States | 155 km (96 mi) | 7.8 C (46.0 F) | 406.3 mm (16.0 in) | 1.09 |
| Buffalo | United States | 162 km (101 mi) | 7.5 C (45.5 F) | 328.7 mm (12.9 in) | 1.09 |
Twins are stations, not cities. A twin is one of the three stations at least 100 km away whose earlier climate is closest to this station's recent one, so a close match does not mean the two places look alike in other ways. A station move or a gap in a record can change that station's averages. The list describes past climate; it is not a forecast and does not say what caused any change. How twins are found, and a search for any station.
Download the Data
Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-15 (15 October 2026). Records are computed by this site and are not official.
Data as of . Last revised (2026-10-15).