Niwot Weather Records (USS0005J42S)
Record envelope, standing records and threshold days for Niwot (USS0005J42S), Colorado, United States, with 47 years of record.
Key Facts for Niwot
- Niwot (USS0005J42S) is a weather station in Colorado, United States at 40.04 latitude and -105.54 longitude, 3,021 m (9,910 ft) above sea level.
- The station reports from 1980 to 2026, 47 years of record.
- 1,464 records set at Niwot still stand.
- Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
- Niwot set a daily record precipitation of 17.8 mm (0.7 in) on 13 October 2026 (provisional).
Provisional Records
Records set in the last 60 days are provisional until they clear the revision window.
About the Station
- Location: Colorado, United States, 40.04 latitude, -105.54 longitude.
- Elevation: 3,021 m (9,910 ft).
- Period of record: 1980 to 2026, 47 years.
- Eligible elements: tmax, tmin, prcp.
Daily Record Envelope and 2026
16 days at or beyond a record| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 15.4 C (59.7 F) | -31.0 C (-23.8 F) | 5.8 C (42.4 F) | -22.1 C (-7.8 F) |
| Feb | 21.5 C (70.7 F) | -30.8 C (-23.4 F) | 8.9 C (48.0 F) | -21.7 C (-7.1 F) |
| Mar | 21.9 C (71.4 F) | -24.2 C (-11.6 F) | 17.6 C (63.7 F) | -14.8 C (5.4 F) |
| Apr | 26.0 C (78.8 F) | -22.6 C (-8.7 F) | 17.7 C (63.9 F) | -11.8 C (10.8 F) |
| May | 25.9 C (78.6 F) | -18.0 C (-0.4 F) | 21.5 C (70.7 F) | -12.0 C (10.4 F) |
| Jun | 35.7 C (96.3 F) | -8.7 C (16.3 F) | 24.9 C (76.8 F) | -1.0 C (30.2 F) |
| Jul | 33.8 C (92.8 F) | -1.8 C (28.8 F) | 28.5 C (83.3 F) | 1.6 C (34.9 F) |
| Aug | 33.2 C (91.8 F) | -7.4 C (18.7 F) | 27.9 C (82.2 F) | 2.5 C (36.5 F) |
| Sep | 33.4 C (92.1 F) | -13.6 C (7.5 F) | 24.2 C (75.6 F) | -1.3 C (29.7 F) |
| Oct | 27.7 C (81.9 F) | -23.9 C (-11.0 F) | 20.3 C (68.5 F) | -2.5 C (27.5 F) |
| Nov | 19.1 C (66.4 F) | -26.5 C (-15.7 F) | n/a | n/a |
| Dec | 18.8 C (65.8 F) | -29.7 C (-21.5 F) | n/a | n/a |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1989 | 9 |
| 1990 | 42 |
| 1991 | 29 |
| 1992 | 36 |
| 1993 | 39 |
| 1994 | 32 |
| 1995 | 48 |
| 1996 | 46 |
| 1997 | 43 |
| 1998 | 34 |
| 1999 | 50 |
| 2000 | 45 |
| 2001 | 32 |
| 2002 | 37 |
| 2003 | 52 |
| 2004 | 32 |
| 2005 | 56 |
| 2006 | 82 |
| 2007 | 34 |
| 2008 | 29 |
| 2009 | 41 |
| 2010 | 24 |
| 2011 | 27 |
| 2012 | 37 |
| 2013 | 43 |
| 2014 | 39 |
| 2015 | 39 |
| 2016 | 31 |
| 2017 | 37 |
| 2018 | 41 |
| 2019 | 30 |
| 2020 | 54 |
| 2021 | 33 |
| 2022 | 50 |
| 2023 | 23 |
| 2024 | 28 |
| 2025 | 47 |
| 2026 | 33 |
Wettest Day of Each Month
Apr: 76.2 mm (3.0 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 33.0 mm (1.3 in) | 30 January 2005 |
| Feb | 22.9 mm (0.9 in) | 18 February 1986 |
| Mar | 71.1 mm (2.8 in) | 18 March 2003 |
| Apr | 76.2 mm (3.0 in) | 2 April 1986 |
| May | 61.0 mm (2.4 in) | 12 May 1982 |
| Jun | 45.7 mm (1.8 in) | 3 June 1981 |
| Jul | 71.1 mm (2.8 in) | 6 July 2012 |
| Aug | 43.2 mm (1.7 in) | 4 August 1999 |
| Sep | 58.4 mm (2.3 in) | 12 September 2013 |
| Oct | 38.1 mm (1.5 in) | 3 October 1984 |
| Nov | 25.4 mm (1.0 in) | 9 November 1985 |
| Dec | 50.8 mm (2.0 in) | 20 December 2006 |
Period of Record Coverage
1989 to 2026| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1989 | 88 | 24% | No |
| 1990 | 362 | 99% | Yes |
| 1991 | 362 | 99% | Yes |
| 1992 | 366 | 100% | Yes |
| 1993 | 350 | 96% | Yes |
| 1994 | 351 | 96% | Yes |
| 1995 | 365 | 100% | Yes |
| 1996 | 358 | 98% | Yes |
| 1997 | 364 | 100% | Yes |
| 1998 | 365 | 100% | Yes |
| 1999 | 363 | 99% | Yes |
| 2000 | 365 | 100% | Yes |
| 2001 | 362 | 99% | Yes |
| 2002 | 365 | 100% | Yes |
| 2003 | 363 | 99% | Yes |
| 2004 | 365 | 100% | Yes |
| 2005 | 259 | 71% | No |
| 2006 | 247 | 68% | No |
| 2007 | 336 | 92% | Yes |
| 2008 | 366 | 100% | Yes |
| 2009 | 365 | 100% | Yes |
| 2010 | 365 | 100% | Yes |
| 2011 | 365 | 100% | Yes |
| 2012 | 366 | 100% | Yes |
| 2013 | 365 | 100% | Yes |
| 2014 | 365 | 100% | Yes |
| 2015 | 365 | 100% | Yes |
| 2016 | 365 | 100% | Yes |
| 2017 | 365 | 100% | Yes |
| 2018 | 365 | 100% | Yes |
| 2019 | 362 | 99% | Yes |
| 2020 | 366 | 100% | Yes |
| 2021 | 365 | 100% | Yes |
| 2022 | 364 | 100% | Yes |
| 2023 | 365 | 100% | Yes |
| 2024 | 365 | 100% | Yes |
| 2025 | 365 | 100% | Yes |
| 2026 | 286 | 78% | No |
Latest Records
20| Date | Station | Record | Value | Beat old record by | Old record stood | Significance |
|---|---|---|---|---|---|---|
| 13 October 2026 | Niwot, US | daily rain (Provisional) | 17.8 mm (0.7 in) | 2.6 mm (0.10 in) | 39 years | 19 of 100 (Routine) |
| 7 October 2026 | Niwot, US | daily high max (Tie, Provisional) | 18.8 C (65.8 F) | tie | 5 years | 1 of 100 (Routine) |
| 6 October 2026 | Niwot, US | daily high max (Provisional) | 20.3 C (68.5 F) | 0.3 C (0.5 F) | 5 years | 4 of 100 (Routine) |
| 6 October 2026 | Niwot, US | daily high min (Tie, Provisional) | 3.9 C (39.0 F) | tie | 29 years | 2 of 100 (Routine) |
| 5 October 2026 | Niwot, US | daily high min (Provisional) | 5.6 C (42.1 F) | 2.7 C (4.9 F) | 15 years | 12 of 100 (Routine) |
| 3 October 2026 | Niwot, US | daily high min (Provisional) | 4.1 C (39.4 F) | 0.1 C (0.2 F) | 8 years | 5 of 100 (Routine) |
| 26 September 2026 | Niwot, US | daily high min (Provisional) | 6.9 C (44.4 F) | 0.5 C (0.9 F) | 28 years | 12 of 100 (Routine) |
| 16 September 2026 | Niwot, US | daily rain (Provisional) | 12.7 mm (0.5 in) | 5.1 mm (0.20 in) | 39 years | 20 of 100 (Routine) |
| 14 September 2026 | Niwot, US | daily high min (Provisional) | 8.5 C (47.3 F) | 2.6 C (4.7 F) | 28 years | 18 of 100 (Routine) |
| 13 September 2026 | Niwot, US | daily high min (Provisional) | 7.9 C (46.2 F) | 3.0 C (5.4 F) | 8 years | 13 of 100 (Routine) |
| 5 September 2026 | Niwot, US | daily high min (Provisional) | 9.2 C (48.6 F) | 0.6 C (1.1 F) | 16 years | 8 of 100 (Routine) |
| 28 August 2026 | Niwot, US | daily high max (Tie, Provisional) | 24.4 C (75.9 F) | tie | 36 years | 3 of 100 (Routine) |
| 21 August 2026 | Niwot, US | daily high max (Provisional) | 27.2 C (81.0 F) | 1.0 C (1.8 F) | 0 years | 5 of 100 (Routine) |
| 13 August 2026 | Niwot, US | daily rain | 17.8 mm (0.7 in) | 5.1 mm (0.20 in) | 35 years | 20 of 100 (Routine) |
| 7 August 2026 | Niwot, US | daily high max | 27.1 C (80.8 F) | 0.1 C (0.2 F) | 23 years | 9 of 100 (Routine) |
| 2 August 2026 | Niwot, US | daily high max | 27.9 C (82.2 F) | 0.8 C (1.4 F) | 17 years | 10 of 100 (Routine) |
| 27 July 2026 | Niwot, US | daily high min | 10.1 C (50.2 F) | 1.3 C (2.3 F) | 16 years | 12 of 100 (Routine) |
| 26 July 2026 | Niwot, US | daily high max | 26.9 C (80.4 F) | 0.9 C (1.6 F) | 23 years | 11 of 100 (Routine) |
| 21 July 2026 | Niwot, US | daily high min | 9.8 C (49.6 F) | 0.3 C (0.5 F) | 4 years | 5 of 100 (Routine) |
| 7 June 2026 | Niwot, US | daily high min | 8.8 C (47.8 F) | 3.7 C (6.7 F) | 20 years | 21 of 100 (Routine) |
Climate Trend
32 complete years, 1991 to 2025| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1991 | 1.6 C | -0.63 C |
| 1992 | 2.0 C | -0.30 C |
| 1993 | 1.1 C | -1.20 C |
| 1994 | 2.4 C | +0.14 C |
| 1995 | 1.8 C | -0.43 C |
| 1996 | 2.2 C | -0.12 C |
| 1997 | 1.7 C | -0.62 C |
| 1998 | 2.2 C | -0.12 C |
| 1999 | 2.4 C | +0.15 C |
| 2000 | 2.7 C | +0.39 C |
| 2001 | 2.8 C | +0.57 C |
| 2002 | 2.3 C | -0.02 C |
| 2003 | 2.8 C | +0.56 C |
| 2004 | 2.1 C | -0.14 C |
| 2008 | 1.5 C | -0.79 C |
| 2009 | 1.7 C | -0.54 C |
| 2010 | 2.1 C | -0.15 C |
| 2011 | 1.9 C | -0.35 C |
| 2012 | 3.1 C | +0.84 C |
| 2013 | 1.6 C | -0.65 C |
| 2014 | 2.1 C | -0.19 C |
| 2015 | 2.9 C | +0.66 C |
| 2016 | 2.9 C | +0.66 C |
| 2017 | 3.2 C | +0.89 C |
| 2018 | 2.6 C | +0.31 C |
| 2019 | 1.9 C | -0.34 C |
| 2020 | 2.6 C | +0.36 C |
| 2021 | 2.5 C | +0.25 C |
| 2022 | 1.9 C | -0.36 C |
| 2023 | 1.8 C | -0.47 C |
| 2024 | 2.9 C | +0.61 C |
| 2025 | 3.2 C | +0.88 C |
The annual mean temperature here has risen by 0.20 C (0.02 to 0.37) per decade over 1991 to 2025. In Fahrenheit: 0.36 F (0.04 to 0.67) per decade. The slope is a straight line fitted to 32 complete years; the brackets give its 95 percent interval.
| Measure | Per decade (C) | Per decade (F) | Period | Complete years | Reading |
|---|---|---|---|---|---|
| Annual mean temperature | 0.20 C (0.02 to 0.37) per decade | 0.36 F (0.04 to 0.67) per decade | 1991 to 2025 | 32 | Rise |
| Mean daily maximum | -0.04 C (-0.27 to 0.19) per decade | -0.1 F (-0.5 to 0.3) per decade | 1991 to 2025 | 32 | Not clearly different from zero |
| Mean daily minimum | 0.4 C (0.3 to 0.6) per decade | 0.8 F (0.5 to 1.1) per decade | 1991 to 2025 | 32 | Rise |
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
1980 to 2026| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 35.7 C (96.3 F) | 2006 | 27.4 C (81.3 F) | 38 |
| Coldest night (TNn) | -31.0 C (-23.8 F) | 2017 | -26.1 C (-15.1 F) | 38 |
| Wettest day (Rx1day) | 76.2 mm (3.0 in) | 1986 | 38.1 mm (1.5 in) | 47 |
| Wettest five days (Rx5day) | 177.7 mm (7.0 in) | 2013 | 76.2 mm (3.0 in) | 47 |
| Longest dry spell (CDD) | 34 days | 2007 | 22 days | 47 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1980 | n/a |
| 1981 | n/a |
| 1982 | n/a |
| 1983 | n/a |
| 1984 | n/a |
| 1985 | n/a |
| 1986 | n/a |
| 1987 | n/a |
| 1988 | n/a |
| 1989 | 18.7 C (65.7 F) |
| 1990 | 28.9 C (84.0 F) |
| 1991 | 25.7 C (78.3 F) |
| 1992 | 25.3 C (77.5 F) |
| 1993 | 28.6 C (83.5 F) |
| 1994 | 27.0 C (80.6 F) |
| 1995 | 28.7 C (83.7 F) |
| 1996 | 27.5 C (81.5 F) |
| 1997 | 28.1 C (82.6 F) |
| 1998 | 29.4 C (84.9 F) |
| 1999 | 26.0 C (78.8 F) |
| 2000 | 27.7 C (81.9 F) |
| 2001 | 28.6 C (83.5 F) |
| 2002 | 28.2 C (82.8 F) |
| 2003 | 30.1 C (86.2 F) |
| 2004 | 26.7 C (80.1 F) |
| 2005 | 33.4 C (92.1 F) |
| 2006 | 35.7 C (96.3 F) |
| 2007 | 27.0 C (80.6 F) |
| 2008 | 27.7 C (81.9 F) |
| 2009 | 25.6 C (78.1 F) |
| 2010 | 26.5 C (79.7 F) |
| 2011 | 25.9 C (78.6 F) |
| 2012 | 27.7 C (81.9 F) |
| 2013 | 26.9 C (80.4 F) |
| 2014 | 25.5 C (77.9 F) |
| 2015 | 25.8 C (78.4 F) |
| 2016 | 26.8 C (80.2 F) |
| 2017 | 27.6 C (81.7 F) |
| 2018 | 27.4 C (81.3 F) |
| 2019 | 26.5 C (79.7 F) |
| 2020 | 26.1 C (79.0 F) |
| 2021 | 27.7 C (81.9 F) |
| 2022 | 26.4 C (79.5 F) |
| 2023 | 27.1 C (80.8 F) |
| 2024 | 27.4 C (81.3 F) |
| 2025 | 27.4 C (81.3 F) |
| 2026 | 28.5 C (83.3 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1980 | n/a |
| 1981 | n/a |
| 1982 | n/a |
| 1983 | n/a |
| 1984 | n/a |
| 1985 | n/a |
| 1986 | n/a |
| 1987 | n/a |
| 1988 | n/a |
| 1989 | -23.3 C (-9.9 F) |
| 1990 | -29.7 C (-21.5 F) |
| 1991 | -28.1 C (-18.6 F) |
| 1992 | -23.8 C (-10.8 F) |
| 1993 | -24.1 C (-11.4 F) |
| 1994 | -28.7 C (-19.7 F) |
| 1995 | -25.4 C (-13.7 F) |
| 1996 | -27.2 C (-17.0 F) |
| 1997 | -30.3 C (-22.5 F) |
| 1998 | -25.0 C (-13.0 F) |
| 1999 | -25.2 C (-13.4 F) |
| 2000 | -23.2 C (-9.8 F) |
| 2001 | -25.7 C (-14.3 F) |
| 2002 | -25.8 C (-14.4 F) |
| 2003 | -22.6 C (-8.7 F) |
| 2004 | -30.8 C (-23.4 F) |
| 2005 | -27.4 C (-17.3 F) |
| 2006 | -25.0 C (-13.0 F) |
| 2007 | -27.4 C (-17.3 F) |
| 2008 | -24.7 C (-12.5 F) |
| 2009 | -27.2 C (-17.0 F) |
| 2010 | -24.8 C (-12.6 F) |
| 2011 | -30.2 C (-22.4 F) |
| 2012 | -22.2 C (-8.0 F) |
| 2013 | -29.8 C (-21.6 F) |
| 2014 | -26.5 C (-15.7 F) |
| 2015 | -25.7 C (-14.3 F) |
| 2016 | -27.4 C (-17.3 F) |
| 2017 | -31.0 C (-23.8 F) |
| 2018 | -26.5 C (-15.7 F) |
| 2019 | -25.3 C (-13.5 F) |
| 2020 | -26.4 C (-15.5 F) |
| 2021 | -28.2 C (-18.8 F) |
| 2022 | -28.6 C (-19.5 F) |
| 2023 | -23.0 C (-9.4 F) |
| 2024 | -28.9 C (-20.0 F) |
| 2025 | -25.9 C (-14.6 F) |
| 2026 | -22.1 C (-7.8 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1980 | 5.1 mm (0.20 in) |
| 1981 | 45.7 mm (1.8 in) |
| 1982 | 61.0 mm (2.4 in) |
| 1983 | 30.5 mm (1.2 in) |
| 1984 | 61.0 mm (2.4 in) |
| 1985 | 33.0 mm (1.3 in) |
| 1986 | 76.2 mm (3.0 in) |
| 1987 | 38.1 mm (1.5 in) |
| 1988 | 43.2 mm (1.7 in) |
| 1989 | 35.6 mm (1.4 in) |
| 1990 | 48.3 mm (1.9 in) |
| 1991 | 33.0 mm (1.3 in) |
| 1992 | 35.6 mm (1.4 in) |
| 1993 | 30.5 mm (1.2 in) |
| 1994 | 20.3 mm (0.8 in) |
| 1995 | 40.6 mm (1.6 in) |
| 1996 | 30.5 mm (1.2 in) |
| 1997 | 61.0 mm (2.4 in) |
| 1998 | 38.1 mm (1.5 in) |
| 1999 | 48.3 mm (1.9 in) |
| 2000 | 27.9 mm (1.1 in) |
| 2001 | 30.5 mm (1.2 in) |
| 2002 | 25.4 mm (1.0 in) |
| 2003 | 71.1 mm (2.8 in) |
| 2004 | 35.6 mm (1.4 in) |
| 2005 | 40.6 mm (1.6 in) |
| 2006 | 50.8 mm (2.0 in) |
| 2007 | 22.9 mm (0.9 in) |
| 2008 | 20.3 mm (0.8 in) |
| 2009 | 76.2 mm (3.0 in) |
| 2010 | 40.6 mm (1.6 in) |
| 2011 | 35.6 mm (1.4 in) |
| 2012 | 71.1 mm (2.8 in) |
| 2013 | 58.4 mm (2.3 in) |
| 2014 | 30.5 mm (1.2 in) |
| 2015 | 43.2 mm (1.7 in) |
| 2016 | 40.6 mm (1.6 in) |
| 2017 | 55.9 mm (2.2 in) |
| 2018 | 33.0 mm (1.3 in) |
| 2019 | 27.9 mm (1.1 in) |
| 2020 | 45.7 mm (1.8 in) |
| 2021 | 27.9 mm (1.1 in) |
| 2022 | 27.9 mm (1.1 in) |
| 2023 | 33.0 mm (1.3 in) |
| 2024 | 48.3 mm (1.9 in) |
| 2025 | 35.6 mm (1.4 in) |
| 2026 | 40.6 mm (1.6 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1980 | 17.7 mm (0.7 in) |
| 1981 | 53.3 mm (2.1 in) |
| 1982 | 96.5 mm (3.8 in) |
| 1983 | 78.7 mm (3.1 in) |
| 1984 | 88.9 mm (3.5 in) |
| 1985 | 58.4 mm (2.3 in) |
| 1986 | 114.3 mm (4.5 in) |
| 1987 | 48.2 mm (1.9 in) |
| 1988 | 55.9 mm (2.2 in) |
| 1989 | 53.3 mm (2.1 in) |
| 1990 | 76.2 mm (3.0 in) |
| 1991 | 68.5 mm (2.7 in) |
| 1992 | 73.6 mm (2.9 in) |
| 1993 | 63.4 mm (2.5 in) |
| 1994 | 48.3 mm (1.9 in) |
| 1995 | 86.5 mm (3.4 in) |
| 1996 | 91.4 mm (3.6 in) |
| 1997 | 106.7 mm (4.2 in) |
| 1998 | 71.0 mm (2.8 in) |
| 1999 | 111.9 mm (4.4 in) |
| 2000 | 45.7 mm (1.8 in) |
| 2001 | 58.4 mm (2.3 in) |
| 2002 | 53.4 mm (2.1 in) |
| 2003 | 149.8 mm (5.9 in) |
| 2004 | 78.8 mm (3.1 in) |
| 2005 | 78.7 mm (3.1 in) |
| 2006 | 91.5 mm (3.6 in) |
| 2007 | 55.9 mm (2.2 in) |
| 2008 | 32.9 mm (1.3 in) |
| 2009 | 114.3 mm (4.5 in) |
| 2010 | 66.0 mm (2.6 in) |
| 2011 | 68.6 mm (2.7 in) |
| 2012 | 111.8 mm (4.4 in) |
| 2013 | 177.7 mm (7.0 in) |
| 2014 | 73.7 mm (2.9 in) |
| 2015 | 94.1 mm (3.7 in) |
| 2016 | 78.7 mm (3.1 in) |
| 2017 | 91.5 mm (3.6 in) |
| 2018 | 50.8 mm (2.0 in) |
| 2019 | 55.8 mm (2.2 in) |
| 2020 | 94.0 mm (3.7 in) |
| 2021 | 78.7 mm (3.1 in) |
| 2022 | 76.2 mm (3.0 in) |
| 2023 | 76.2 mm (3.0 in) |
| 2024 | 99.1 mm (3.9 in) |
| 2025 | 58.4 mm (2.3 in) |
| 2026 | 66.0 mm (2.6 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1980 | 14 days |
| 1981 | 29 days |
| 1982 | 17 days |
| 1983 | 13 days |
| 1984 | 20 days |
| 1985 | 15 days |
| 1986 | 18 days |
| 1987 | 26 days |
| 1988 | 25 days |
| 1989 | 25 days |
| 1990 | 32 days |
| 1991 | 26 days |
| 1992 | 33 days |
| 1993 | 20 days |
| 1994 | 14 days |
| 1995 | 20 days |
| 1996 | 23 days |
| 1997 | 31 days |
| 1998 | 17 days |
| 1999 | 25 days |
| 2000 | 17 days |
| 2001 | 14 days |
| 2002 | 22 days |
| 2003 | 27 days |
| 2004 | 14 days |
| 2005 | 18 days |
| 2006 | 23 days |
| 2007 | 34 days |
| 2008 | 22 days |
| 2009 | 13 days |
| 2010 | 24 days |
| 2011 | 22 days |
| 2012 | 33 days |
| 2013 | 28 days |
| 2014 | 11 days |
| 2015 | 24 days |
| 2016 | 17 days |
| 2017 | 16 days |
| 2018 | 26 days |
| 2019 | 24 days |
| 2020 | 27 days |
| 2021 | 15 days |
| 2022 | 23 days |
| 2023 | 13 days |
| 2024 | 32 days |
| 2025 | 15 days |
| 2026 | 28 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
32 years with a frostAcross 32 years with a frost, the median last spring frost at Niwot falls on 20 June and the median first autumn frost on 8 August, which leaves a median of 51 days between them.
Fitted over all years, the growing season changes by +12.1 days per decade at this station.
| Measure | Median, all years | Earliest period | Recent period (1993 to 2025) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 20 June | n/a | 20 June | n/a | -2.9 days per decade |
| First autumn frost | 8 August | n/a | 12 August | n/a | +9.3 days per decade |
| Growing days | 51 days | n/a | 53 days | n/a | +12.1 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
45 years, 1981 to 2025A day with at least 38.4 mm (1.5 in) of rain is expected about once in 2 years. A day with at least 93.8 mm (3.7 in) of rain is expected about once in 100 years.
| Expected about once in | A day with at least | Note |
|---|---|---|
| 2 years | 38.4 mm (1.5 in) | |
| 5 years | 51.6 mm (2.0 in) | |
| 10 years | 60.9 mm (2.4 in) | |
| 25 years | 73.5 mm (2.9 in) | |
| 50 years | 83.4 mm (3.3 in) | Longer than the 45 years of record |
| 100 years | 93.8 mm (3.7 in) | Longer than the 45 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, 45 years of values from 1981 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: 76.2 mm (3.0 in) in 1986; 76.2 mm (3.0 in) in 2009; 71.1 mm (2.8 in) in 2003.
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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 2026-10-17 (17 October 2026). Records are computed by this site and are not official.
Data as of . Last revised (2026-10-17).