Rocky Boy Weather Records (USS0009A01S)
Record envelope, standing records and threshold days for Rocky Boy (USS0009A01S), Montana, United States, with 31 years of record.
Key Facts for Rocky Boy
- Rocky Boy (USS0009A01S) is a weather station in Montana, United States at 48.17 latitude and -109.65 longitude, 1,433 m (4,700 ft) above sea level.
- The station reports from 1996 to 2026, 31 years of record.
- 1,464 records set at Rocky Boy still stand.
- Records are tracked for tmax, tmin: an element needs 30 years of data to be eligible.
- Rocky Boy set a daily record low minimum temperature of -4.2 C (24.4 F) on 27 September 2026 (provisional).
Provisional Records
Records set in the last 60 days are provisional until they clear the revision window.
About the Station
- Location: Montana, United States, 48.17 latitude, -109.65 longitude.
- Elevation: 1,433 m (4,700 ft).
- Period of record: 1996 to 2026, 31 years.
- Eligible elements: tmax, tmin.
Daily Record Envelope and 2026
23 days at or beyond a record| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 17.3 C (63.1 F) | -38.6 C (-37.5 F) | 12.6 C (54.7 F) | -32.1 C (-25.8 F) |
| Feb | 17.1 C (62.8 F) | -36.4 C (-33.5 F) | 13.9 C (57.0 F) | -25.6 C (-14.1 F) |
| Mar | 21.2 C (70.2 F) | -33.1 C (-27.6 F) | 19.2 C (66.6 F) | -26.6 C (-15.9 F) |
| Apr | 25.0 C (77.0 F) | -24.1 C (-11.4 F) | 19.3 C (66.7 F) | -12.7 C (9.1 F) |
| May | 28.1 C (82.6 F) | -13.8 C (7.2 F) | 27.6 C (81.7 F) | -9.7 C (14.5 F) |
| Jun | 33.3 C (91.9 F) | -4.4 C (24.1 F) | 23.9 C (75.0 F) | -0.9 C (30.4 F) |
| Jul | 35.7 C (96.3 F) | 0.0 C (32.0 F) | 34.3 C (93.7 F) | 4.0 C (39.2 F) |
| Aug | 36.5 C (97.7 F) | -2.2 C (28.0 F) | 33.7 C (92.7 F) | -0.9 C (30.4 F) |
| Sep | 33.6 C (92.5 F) | -12.3 C (9.9 F) | 24.7 C (76.5 F) | -4.2 C (24.4 F) |
| Oct | 28.0 C (82.4 F) | -22.9 C (-9.2 F) | 23.2 C (73.8 F) | -5.7 C (21.7 F) |
| Nov | 23.0 C (73.4 F) | -27.5 C (-17.5 F) | n/a | n/a |
| Dec | 16.2 C (61.2 F) | -37.4 C (-35.3 F) | n/a | n/a |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1996 | 43 |
| 1997 | 51 |
| 1998 | 37 |
| 1999 | 45 |
| 2000 | 34 |
| 2001 | 26 |
| 2002 | 52 |
| 2003 | 56 |
| 2004 | 36 |
| 2005 | 64 |
| 2006 | 50 |
| 2007 | 42 |
| 2008 | 42 |
| 2009 | 52 |
| 2010 | 44 |
| 2011 | 31 |
| 2012 | 55 |
| 2013 | 42 |
| 2014 | 46 |
| 2015 | 44 |
| 2016 | 53 |
| 2017 | 52 |
| 2018 | 31 |
| 2019 | 46 |
| 2020 | 48 |
| 2021 | 71 |
| 2022 | 72 |
| 2023 | 54 |
| 2024 | 60 |
| 2025 | 42 |
| 2026 | 43 |
Wettest Day of Each Month
Sep: 137.2 mm (5.4 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 50.8 mm (2.0 in) | 11 January 2025 |
| Feb | 25.4 mm (1.0 in) | 26 February 1999 |
| Mar | 20.3 mm (0.8 in) | 27 March 2007 |
| Apr | 66.0 mm (2.6 in) | 29 April 2010 |
| May | 134.6 mm (5.3 in) | 7 May 2024 |
| Jun | 99.1 mm (3.9 in) | 27 June 1998 |
| Jul | 61.0 mm (2.4 in) | 28 July 2015 |
| Aug | 71.1 mm (2.8 in) | 23 August 2014 |
| Sep | 137.2 mm (5.4 in) | 18 September 2024 |
| Oct | 61.0 mm (2.4 in) | 31 October 2016 |
| Nov | 43.2 mm (1.7 in) | 5 November 2024 |
| Dec | 43.2 mm (1.7 in) | 10 December 2025 |
Period of Record Coverage
1996 to 2026| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1996 | 204 | 56% | No |
| 1997 | 365 | 100% | Yes |
| 1998 | 365 | 100% | Yes |
| 1999 | 363 | 99% | Yes |
| 2000 | 366 | 100% | Yes |
| 2001 | 364 | 100% | Yes |
| 2002 | 364 | 100% | Yes |
| 2003 | 365 | 100% | Yes |
| 2004 | 365 | 100% | Yes |
| 2005 | 364 | 100% | Yes |
| 2006 | 365 | 100% | Yes |
| 2007 | 365 | 100% | Yes |
| 2008 | 365 | 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 | 366 | 100% | Yes |
| 2017 | 364 | 100% | Yes |
| 2018 | 365 | 100% | Yes |
| 2019 | 363 | 99% | Yes |
| 2020 | 363 | 99% | Yes |
| 2021 | 364 | 100% | Yes |
| 2022 | 363 | 99% | Yes |
| 2023 | 364 | 100% | Yes |
| 2024 | 366 | 100% | Yes |
| 2025 | 363 | 99% | Yes |
| 2026 | 277 | 76% | No |
Latest Records
20| Date | Station | Record | Value | Beat old record by | Old record stood | Significance |
|---|---|---|---|---|---|---|
| 27 September 2026 | Rocky Boy, US | daily low min (Provisional) | -4.2 C (24.4 F) | 0.1 C (0.2 F) | 16 years | 8 of 100 (Routine) |
| 22 August 2026 | Rocky Boy, US | daily high min (Tie, Provisional) | 13.6 C (56.5 F) | tie | 23 years | 2 of 100 (Routine) |
| 14 August 2026 | Rocky Boy, US | daily low max | 14.8 C (58.6 F) | 0.5 C (0.9 F) | 16 years | 8 of 100 (Routine) |
| 5 August 2026 | Rocky Boy, US | daily low min | 1.7 C (35.1 F) | 1.6 C (2.9 F) | 4 years | 8 of 100 (Routine) |
| 4 August 2026 | Rocky Boy, US | daily low min | -0.9 C (30.4 F) | 3.0 C (5.4 F) | 17 years | 17 of 100 (Routine) |
| 3 August 2026 | Rocky Boy, US | daily low min | -0.2 C (31.6 F) | 2.1 C (3.8 F) | 24 years | 16 of 100 (Routine) |
| 1 August 2026 | Rocky Boy, US | daily high max | 33.7 C (92.7 F) | 1.3 C (2.3 F) | 4 years | 6 of 100 (Routine) |
| 25 July 2026 | Rocky Boy, US | daily high max | 34.3 C (93.7 F) | 2.4 C (4.3 F) | 1 year | 8 of 100 (Routine) |
| 14 July 2026 | Rocky Boy, US | daily high min | 14.4 C (57.9 F) | 0.2 C (0.4 F) | 24 years | 10 of 100 (Routine) |
| 12 July 2026 | Rocky Boy, US | daily high max | 34.1 C (93.4 F) | 1.5 C (2.7 F) | 24 years | 13 of 100 (Routine) |
| 29 June 2026 | Rocky Boy, US | daily low max | 11.8 C (53.2 F) | 0.4 C (0.7 F) | 20 years | 9 of 100 (Routine) |
| 14 June 2026 | Rocky Boy, US | daily low min | -0.9 C (30.4 F) | 1.3 C (2.3 F) | 17 years | 11 of 100 (Routine) |
| 2 June 2026 | Rocky Boy, US | daily low max | 7.6 C (45.7 F) | 0.2 C (0.4 F) | 28 years | 11 of 100 (Routine) |
| 1 June 2026 | Rocky Boy, US | daily low max | 5.7 C (42.3 F) | 1.2 C (2.2 F) | 25 years | 12 of 100 (Routine) |
| 29 May 2026 | Rocky Boy, US | daily high max | 26.1 C (79.0 F) | 2.3 C (4.1 F) | 0 years | 6 of 100 (Routine) |
| 28 May 2026 | Rocky Boy, US | daily high max | 27.6 C (81.7 F) | 2.8 C (5.0 F) | 8 years | 9 of 100 (Routine) |
| 27 May 2026 | Rocky Boy, US | daily high max | 26.4 C (79.5 F) | 2.9 C (5.2 F) | 27 years | 15 of 100 (Routine) |
| 27 May 2026 | Rocky Boy, US | daily high min | 11.5 C (52.7 F) | 1.6 C (2.9 F) | 16 years | 12 of 100 (Routine) |
| 26 May 2026 | Rocky Boy, US | daily high max | 27.0 C (80.6 F) | 2.6 C (4.7 F) | 8 years | 9 of 100 (Routine) |
| 17 May 2026 | Rocky Boy, US | daily low max | 1.1 C (34.0 F) | 3.4 C (6.1 F) | 11 years | 11 of 100 (Routine) |
Climate Trend
29 complete years, 1997 to 2025| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1997 | 3.7 C | -0.49 C |
| 1998 | 4.5 C | +0.34 C |
| 1999 | 4.6 C | +0.42 C |
| 2000 | 3.3 C | -0.87 C |
| 2001 | 4.4 C | +0.20 C |
| 2002 | 2.9 C | -1.33 C |
| 2003 | 4.3 C | +0.08 C |
| 2004 | 3.9 C | -0.26 C |
| 2005 | 4.3 C | +0.08 C |
| 2006 | 5.1 C | +0.94 C |
| 2007 | 4.7 C | +0.49 C |
| 2008 | 3.4 C | -0.82 C |
| 2009 | 3.4 C | -0.83 C |
| 2010 | 3.9 C | -0.32 C |
| 2011 | 3.7 C | -0.47 C |
| 2012 | 5.1 C | +0.86 C |
| 2013 | 4.1 C | -0.14 C |
| 2014 | 3.7 C | -0.47 C |
| 2015 | 5.5 C | +1.28 C |
| 2016 | 5.3 C | +1.07 C |
| 2017 | 4.6 C | +0.39 C |
| 2018 | 3.8 C | -0.44 C |
| 2019 | 2.7 C | -1.45 C |
| 2020 | 4.3 C | +0.12 C |
| 2021 | 4.3 C | +0.11 C |
| 2022 | 3.7 C | -0.48 C |
| 2023 | 4.8 C | +0.64 C |
| 2024 | 5.0 C | +0.79 C |
| 2025 | 4.6 C | +0.43 C |
This station does not have enough complete years (30 are needed) to fit a temperature trend.
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
1996 to 2026| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 36.5 C (97.7 F) | 2018 | 32.9 C (91.2 F) | 31 |
| Coldest night (TNn) | -38.6 C (-37.5 F) | 2024 | -32.9 C (-27.2 F) | 31 |
| Wettest day (Rx1day) | 137.2 mm (5.4 in) | 2024 | 40.6 mm (1.6 in) | 31 |
| Wettest five days (Rx5day) | 233.6 mm (9.2 in) | 2013 | 96.4 mm (3.8 in) | 31 |
| Longest dry spell (CDD) | 80 days | 2017 | 27 days | 31 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1996 | 32.8 C (91.0 F) |
| 1997 | 29.8 C (85.6 F) |
| 1998 | 31.5 C (88.7 F) |
| 1999 | 31.3 C (88.3 F) |
| 2000 | 31.2 C (88.2 F) |
| 2001 | 34.3 C (93.7 F) |
| 2002 | 32.9 C (91.2 F) |
| 2003 | 33.0 C (91.4 F) |
| 2004 | 31.8 C (89.2 F) |
| 2005 | 31.5 C (88.7 F) |
| 2006 | 33.0 C (91.4 F) |
| 2007 | 34.6 C (94.3 F) |
| 2008 | 32.2 C (90.0 F) |
| 2009 | 30.8 C (87.4 F) |
| 2010 | 32.0 C (89.6 F) |
| 2011 | 33.6 C (92.5 F) |
| 2012 | 32.9 C (91.2 F) |
| 2013 | 33.7 C (92.7 F) |
| 2014 | 31.6 C (88.9 F) |
| 2015 | 33.0 C (91.4 F) |
| 2016 | 33.0 C (91.4 F) |
| 2017 | 33.7 C (92.7 F) |
| 2018 | 36.5 C (97.7 F) |
| 2019 | 32.4 C (90.3 F) |
| 2020 | 33.0 C (91.4 F) |
| 2021 | 34.4 C (93.9 F) |
| 2022 | 34.4 C (93.9 F) |
| 2023 | 32.6 C (90.7 F) |
| 2024 | 35.7 C (96.3 F) |
| 2025 | 30.4 C (86.7 F) |
| 2026 | 34.3 C (93.7 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1996 | -30.7 C (-23.3 F) |
| 1997 | -35.3 C (-31.5 F) |
| 1998 | -33.6 C (-28.5 F) |
| 1999 | -25.7 C (-14.3 F) |
| 2000 | -32.0 C (-25.6 F) |
| 2001 | -26.2 C (-15.2 F) |
| 2002 | -29.3 C (-20.7 F) |
| 2003 | -31.8 C (-25.2 F) |
| 2004 | -33.3 C (-27.9 F) |
| 2005 | -33.9 C (-29.0 F) |
| 2006 | -32.8 C (-27.0 F) |
| 2007 | -30.3 C (-22.5 F) |
| 2008 | -37.1 C (-34.8 F) |
| 2009 | -33.1 C (-27.6 F) |
| 2010 | -28.4 C (-19.1 F) |
| 2011 | -34.2 C (-29.6 F) |
| 2012 | -31.0 C (-23.8 F) |
| 2013 | -37.4 C (-35.3 F) |
| 2014 | -34.7 C (-30.5 F) |
| 2015 | -26.4 C (-15.5 F) |
| 2016 | -34.1 C (-29.4 F) |
| 2017 | -32.9 C (-27.2 F) |
| 2018 | -31.8 C (-25.2 F) |
| 2019 | -35.0 C (-31.0 F) |
| 2020 | -31.5 C (-24.7 F) |
| 2021 | -36.4 C (-33.5 F) |
| 2022 | -35.5 C (-31.9 F) |
| 2023 | -31.2 C (-24.2 F) |
| 2024 | -38.6 C (-37.5 F) |
| 2025 | -33.1 C (-27.6 F) |
| 2026 | -32.1 C (-25.8 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1996 | 17.8 mm (0.7 in) |
| 1997 | 30.5 mm (1.2 in) |
| 1998 | 99.1 mm (3.9 in) |
| 1999 | 30.5 mm (1.2 in) |
| 2000 | 33.0 mm (1.3 in) |
| 2001 | 38.1 mm (1.5 in) |
| 2002 | 38.1 mm (1.5 in) |
| 2003 | 30.5 mm (1.2 in) |
| 2004 | 33.0 mm (1.3 in) |
| 2005 | 43.2 mm (1.7 in) |
| 2006 | 35.6 mm (1.4 in) |
| 2007 | 35.6 mm (1.4 in) |
| 2008 | 40.6 mm (1.6 in) |
| 2009 | 30.5 mm (1.2 in) |
| 2010 | 76.2 mm (3.0 in) |
| 2011 | 71.1 mm (2.8 in) |
| 2012 | 66.0 mm (2.6 in) |
| 2013 | 78.7 mm (3.1 in) |
| 2014 | 71.1 mm (2.8 in) |
| 2015 | 61.0 mm (2.4 in) |
| 2016 | 61.0 mm (2.4 in) |
| 2017 | 58.4 mm (2.3 in) |
| 2018 | 27.9 mm (1.1 in) |
| 2019 | 53.3 mm (2.1 in) |
| 2020 | 38.1 mm (1.5 in) |
| 2021 | 38.1 mm (1.5 in) |
| 2022 | 99.1 mm (3.9 in) |
| 2023 | 33.0 mm (1.3 in) |
| 2024 | 137.2 mm (5.4 in) |
| 2025 | 50.8 mm (2.0 in) |
| 2026 | 68.6 mm (2.7 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1996 | 22.8 mm (0.9 in) |
| 1997 | 58.4 mm (2.3 in) |
| 1998 | 170.2 mm (6.7 in) |
| 1999 | 55.9 mm (2.2 in) |
| 2000 | 60.9 mm (2.4 in) |
| 2001 | 43.2 mm (1.7 in) |
| 2002 | 101.6 mm (4.0 in) |
| 2003 | 71.1 mm (2.8 in) |
| 2004 | 61.0 mm (2.4 in) |
| 2005 | 89.0 mm (3.5 in) |
| 2006 | 96.6 mm (3.8 in) |
| 2007 | 71.2 mm (2.8 in) |
| 2008 | 99.0 mm (3.9 in) |
| 2009 | 48.2 mm (1.9 in) |
| 2010 | 114.2 mm (4.5 in) |
| 2011 | 106.7 mm (4.2 in) |
| 2012 | 96.4 mm (3.8 in) |
| 2013 | 233.6 mm (9.2 in) |
| 2014 | 121.8 mm (4.8 in) |
| 2015 | 121.9 mm (4.8 in) |
| 2016 | 106.7 mm (4.2 in) |
| 2017 | 104.0 mm (4.1 in) |
| 2018 | 63.5 mm (2.5 in) |
| 2019 | 124.4 mm (4.9 in) |
| 2020 | 63.5 mm (2.5 in) |
| 2021 | 83.8 mm (3.3 in) |
| 2022 | 165.1 mm (6.5 in) |
| 2023 | 58.4 mm (2.3 in) |
| 2024 | 215.8 mm (8.5 in) |
| 2025 | 86.3 mm (3.4 in) |
| 2026 | 137.2 mm (5.4 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1996 | 11 days |
| 1997 | 17 days |
| 1998 | 27 days |
| 1999 | 17 days |
| 2000 | 22 days |
| 2001 | 31 days |
| 2002 | 20 days |
| 2003 | 28 days |
| 2004 | 31 days |
| 2005 | 53 days |
| 2006 | 44 days |
| 2007 | 25 days |
| 2008 | 21 days |
| 2009 | 39 days |
| 2010 | 25 days |
| 2011 | 65 days |
| 2012 | 43 days |
| 2013 | 27 days |
| 2014 | 50 days |
| 2015 | 25 days |
| 2016 | 19 days |
| 2017 | 80 days |
| 2018 | 52 days |
| 2019 | 45 days |
| 2020 | 24 days |
| 2021 | 26 days |
| 2022 | 31 days |
| 2023 | 32 days |
| 2024 | 28 days |
| 2025 | 16 days |
| 2026 | 18 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
29 years with a frostAcross 29 years with a frost, the median last spring frost at Rocky Boy falls on 15 June and the median first autumn frost on 4 September, which leaves a median of 84 days between them.
Fitted over all years, the growing season changes by +1.9 days per decade at this station.
| Measure | Median, all years | Earliest period | Recent period (1997 to 2025) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 15 June | n/a | 15 June | n/a | +3.0 days per decade |
| First autumn frost | 4 September | n/a | 4 September | n/a | +4.9 days per decade |
| Growing days | 84 days | n/a | 84 days | n/a | +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.
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 2026-10-17 (17 October 2026). Records are computed by this site and are not official.
Data as of . Last revised (2026-10-17).