Built 2026-10-18 (18 October 2026)

Thunder Basin Weather Records (USS0020A07S)

Record envelope, standing records and threshold days for Thunder Basin (USS0020A07S), Washington, United States, with 39 years of record.

Key Facts for Thunder Basin

  • Thunder Basin (USS0020A07S) is a weather station in Washington, United States at 48.53 latitude and -120.99 longitude, 1,317 m (4,320 ft) above sea level.
  • The station reports from 1988 to 2026, 39 years of record.
  • 1,464 records set at Thunder Basin still stand.
  • Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
  • Thunder Basin tied a daily record low maximum temperature of 2.2 C (36.0 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: Washington, United States, 48.53 latitude, -120.99 longitude.
  • Elevation: 1,317 m (4,320 ft).
  • Period of record: 1988 to 2026, 39 years.
  • Eligible elements: tmax, tmin, prcp.

Daily Record Envelope and 2026

7 days at or beyond a record
Daily record high and record low at Thunder Basin, with 2026 drawn through them The band shows the record high and record low for each calendar day at Thunder Basin. The lines show the 2026 daily maximum and minimum. 7 days in 2026 matched or passed a record. Temperatures are in degrees Celsius. -40-2002040 JanFebMarAprMayJunJulAugSepOctNovDec
The band shows the record high and record low for each calendar day at Thunder Basin. The lines show the 2026 daily maximum and minimum. 7 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.
Daily record high and record low at Thunder Basin, with 2026 drawn through them
MonthHighest record highLowest record low2026 highest maximum2026 lowest minimum
Jan11.9 C (53.4 F)-31.7 C (-25.1 F)7.2 C (45.0 F)-14.2 C (6.4 F)
Feb16.2 C (61.2 F)-29.6 C (-21.3 F)10.7 C (51.3 F)-17.3 C (0.9 F)
Mar18.0 C (64.4 F)-24.4 C (-11.9 F)10.5 C (50.9 F)-11.1 C (12.0 F)
Apr22.1 C (71.8 F)-17.5 C (0.5 F)18.2 C (64.8 F)-5.9 C (21.4 F)
May27.1 C (80.8 F)-11.6 C (11.1 F)24.7 C (76.5 F)-1.7 C (28.9 F)
Jun36.4 C (97.5 F)-5.5 C (22.1 F)25.3 C (77.5 F)-2.3 C (27.9 F)
Jul34.6 C (94.3 F)-3.1 C (26.4 F)31.1 C (88.0 F)1.7 C (35.1 F)
Aug34.0 C (93.2 F)-3.7 C (25.3 F)28.9 C (84.0 F)1.3 C (34.3 F)
Sep30.5 C (86.9 F)-5.1 C (22.8 F)22.0 C (71.6 F)-1.9 C (28.6 F)
Oct25.7 C (78.3 F)-12.0 C (10.4 F)19.5 C (67.1 F)-4.4 C (24.1 F)
Nov14.7 C (58.5 F)-25.9 C (-14.6 F)n/an/a
Dec12.2 C (54.0 F)-32.7 C (-26.9 F)n/an/a

Which Years Hold Standing Records

1,464 standing records
Standing records at Thunder Basin by the year they were set 1,464 records at Thunder Basin still stand. 1999 holds the most, with 116. 0501001501988: 131989: 371990: 451991: 201992: 401993: 341994: 401995: 371996: 571997: 181998: 391999: 1162000: 342001: 302002: 422003: 332004: 162005: 492006: 262007: 242008: 472009: 422010: 322011: 312012: 372013: 322014: 442015: 502016: 382017: 292018: 272019: 432020: 302021: 432022: 502023: 372024: 412025: 372026: 241988199219962000200420082012201620202024
1,464 records at Thunder Basin still stand. 1999 holds the most, with 116.
Standing records at Thunder Basin by the year they were set
Year setStanding records
198813
198937
199045
199120
199240
199334
199440
199537
199657
199718
199839
1999116
200034
200130
200242
200333
200416
200549
200626
200724
200847
200942
201032
201131
201237
201332
201444
201550
201638
201729
201827
201943
202030
202143
202250
202337
202441
202537
202624

All-Time Record Progression

2 new records
When Thunder Basin set new all-time records 2 all-time records were set at Thunder Basin between 29 June 2021 and 31 July 2021. Each dot is a new record. Record high maximum temperatureRecord high minimum temperature29 June 2021: Record high maximum temperature 36.4 C (97.5 F)31 July 2021: Record high minimum temperature 13.6 C (56.5 F)
2 all-time records were set at Thunder Basin between 29 June 2021 and 31 July 2021. Each dot is a new record.
When Thunder Basin set new all-time records
DateKindDetail
2021-06-29Record high maximum temperatureRecord high maximum temperature 36.4 C (97.5 F)
2021-07-31Record high minimum temperatureRecord high minimum temperature 13.6 C (56.5 F)

Wettest Day of Each Month

Nov: 193.0 mm (7.6 in)
Record daily precipitation for each month at Thunder Basin The wettest day on record for each calendar month at Thunder Basin. The most was 193.0 mm (7.6 in) on 6 November 2006. 050100150200 Jan: 119.4 mm (4.7 in), 7 January 2009 Jan Feb: 111.8 mm (4.4 in), 21 February 2002 Feb Mar: 96.5 mm (3.8 in), 18 March 1997 Mar Apr: 66.0 mm (2.6 in), 3 April 1991 Apr May: 43.2 mm (1.7 in), 3 May 2010 May Jun: 61.0 mm (2.4 in), 9 June 2022 Jun Jul: 53.3 mm (2.1 in), 8 July 1997 Jul Aug: 50.8 mm (2.0 in), 22 August 2001 Aug Sep: 96.5 mm (3.8 in), 28 September 2013 Sep Oct: 167.6 mm (6.6 in), 20 October 2003 Oct Nov: 193.0 mm (7.6 in), 6 November 2006 Nov Dec: 139.7 mm (5.5 in), 10 December 2025 Dec
The wettest day on record for each calendar month at Thunder Basin. The most was 193.0 mm (7.6 in) on 6 November 2006.
Record daily precipitation for each month at Thunder Basin
MonthRecord daily precipitation (mm)Date
Jan119.4 mm (4.7 in)7 January 2009
Feb111.8 mm (4.4 in)21 February 2002
Mar96.5 mm (3.8 in)18 March 1997
Apr66.0 mm (2.6 in)3 April 1991
May43.2 mm (1.7 in)3 May 2010
Jun61.0 mm (2.4 in)9 June 2022
Jul53.3 mm (2.1 in)8 July 1997
Aug50.8 mm (2.0 in)22 August 2001
Sep96.5 mm (3.8 in)28 September 2013
Oct167.6 mm (6.6 in)20 October 2003
Nov193.0 mm (7.6 in)6 November 2006
Dec139.7 mm (5.5 in)10 December 2025

Period of Record Coverage

1988 to 2026
Days with data per year at Thunder Basin 39 years of record at Thunder Basin, 1988 to 2026. 5 years have data for under 90 percent of days and are left out of rankings: 1988, 1991, 1992, 2004, 2026. 1988: 140 of 366 days1989: 360 of 365 days1990: 353 of 365 days1991: 265 of 365 days1992: 194 of 366 days1993: 339 of 365 days1994: 355 of 365 days1995: 361 of 365 days1996: 365 of 366 days1997: 363 of 365 days1998: 364 of 365 days1999: 363 of 365 days2000: 360 of 366 days2001: 365 of 365 days2002: 365 of 365 days2003: 362 of 365 days2004: 170 of 366 days2005: 365 of 365 days2006: 363 of 365 days2007: 365 of 365 days2008: 366 of 366 days2009: 364 of 365 days2010: 365 of 365 days2011: 365 of 365 days2012: 364 of 366 days2013: 363 of 365 days2014: 365 of 365 days2015: 365 of 365 days2016: 366 of 366 days2017: 365 of 365 days2018: 365 of 365 days2019: 365 of 365 days2020: 366 of 366 days2021: 363 of 365 days2022: 353 of 365 days2023: 357 of 365 days2024: 348 of 366 days2025: 345 of 365 days2026: 281 of 365 days19901995200020052010201520202025
39 years of record at Thunder Basin, 1988 to 2026. 5 years have data for under 90 percent of days and are left out of rankings: 1988, 1991, 1992, 2004, 2026.
Days with data per year at Thunder Basin
YearDays with dataShare of yearComplete
198814038%No
198936099%Yes
199035397%Yes
199126573%No
199219453%No
199333993%Yes
199435597%Yes
199536199%Yes
1996365100%Yes
199736399%Yes
1998364100%Yes
199936399%Yes
200036098%Yes
2001365100%Yes
2002365100%Yes
200336299%Yes
200417046%No
2005365100%Yes
200636399%Yes
2007365100%Yes
2008366100%Yes
2009364100%Yes
2010365100%Yes
2011365100%Yes
201236499%Yes
201336399%Yes
2014365100%Yes
2015365100%Yes
2016366100%Yes
2017365100%Yes
2018365100%Yes
2019365100%Yes
2020366100%Yes
202136399%Yes
202235397%Yes
202335798%Yes
202434895%Yes
202534595%Yes
202628177%No

Latest Records

20
Latest records at Thunder Basin
DateStationRecordValueBeat old record byOld record stoodSignificance
10 October 2026Thunder Basin, USdaily low max (Tie, Provisional)2.2 C (36.0 F)tie9 years1 of 100 (Routine)
26 September 2026Thunder Basin, USdaily low min (Provisional)-1.7 C (28.9 F)0.5 C (0.9 F)27 years12 of 100 (Routine)
4 September 2026Thunder Basin, USdaily rain (Provisional)7.6 mm (0.30 in)2.5 mm (0.10 in)33 years14 of 100 (Routine)
29 August 2026Thunder Basin, USdaily low max (Provisional)8.8 C (47.8 F)0.8 C (1.4 F)20 years10 of 100 (Routine)
22 August 2026Thunder Basin, USdaily high min (Provisional)10.0 C (50.0 F)1.7 C (3.1 F)24 years16 of 100 (Routine)
21 August 2026Thunder Basin, USdaily high max (Provisional)28.9 C (84.0 F)0.7 C (1.3 F)20 years10 of 100 (Routine)
23 July 2026Thunder Basin, USdaily high min11.3 C (52.3 F)0.4 C (0.7 F)19 years9 of 100 (Routine)
23 June 2026Thunder Basin, USdaily high max24.9 C (76.8 F)0.6 C (1.1 F)5 years5 of 100 (Routine)
15 June 2026Thunder Basin, USdaily high max25.3 C (77.5 F)2.2 C (4.0 F)37 years17 of 100 (Routine)
15 June 2026Thunder Basin, USdaily high min6.5 C (43.7 F)0.3 C (0.5 F)32 years13 of 100 (Routine)
14 June 2026Thunder Basin, USdaily high max24.5 C (76.1 F)0.8 C (1.4 F)37 years15 of 100 (Routine)
3 June 2026Thunder Basin, USdaily high min6.4 C (43.5 F)1.0 C (1.8 F)11 years9 of 100 (Routine)
28 May 2026Thunder Basin, USdaily high min5.4 C (41.7 F)0.8 C (1.4 F)0 years6 of 100 (Routine)
27 May 2026Thunder Basin, USdaily high min6.2 C (43.2 F)1.9 C (3.4 F)11 years14 of 100 (Routine)
15 May 2026Thunder Basin, USdaily low max2.9 C (37.2 F)3.0 C (5.4 F)4 years9 of 100 (Routine)
8 May 2026Thunder Basin, USdaily high min2.3 C (36.1 F)1.6 C (2.9 F)9 years11 of 100 (Routine)
7 May 2026Thunder Basin, USdaily high min2.8 C (37.0 F)1.5 C (2.7 F)0 years9 of 100 (Routine)
6 May 2026Thunder Basin, USdaily high min1.6 C (34.9 F)0.7 C (1.3 F)4 years7 of 100 (Routine)
5 May 2026Thunder Basin, USdaily high min1.6 C (34.9 F)0.7 C (1.3 F)3 years6 of 100 (Routine)
3 May 2026Thunder Basin, USdaily high max20.8 C (69.4 F)0.8 C (1.4 F)28 years12 of 100 (Routine)

Climate Trend

33 complete years, 1989 to 2025
Annual mean temperature at Thunder Basin as warming stripes, 1989 to 2025 One stripe for each of 33 complete years at Thunder Basin, 1989 to 2025. Blue stripes are years cooler than the station's own mean of 4.1 C (39.4 F); red stripes are warmer. The coolest year was 1999, at 2.1 C (35.8 F), and the warmest was 2015, at 5.8 C (42.4 F). The strongest colour marks a difference of 2.1 C (3.8 F). 1989: 3.2 C, -0.9 C from the station mean1990: 3.6 C, -0.6 C from the station mean1993: 3.3 C, -0.8 C from the station mean1994: 4.0 C, -0.2 C from the station mean1995: 3.8 C, -0.3 C from the station mean1996: 2.7 C, -1.4 C from the station mean1997: 3.7 C, -0.4 C from the station mean1998: 4.6 C, +0.5 C from the station mean1999: 2.1 C, -2.0 C from the station mean2000: 3.0 C, -1.1 C from the station mean2001: 3.4 C, -0.7 C from the station mean2002: 3.6 C, -0.5 C from the station mean2003: 4.5 C, +0.4 C from the station mean2005: 4.8 C, +0.6 C from the station mean2006: 4.4 C, +0.3 C from the station mean2007: 4.2 C, +0.1 C from the station mean2008: 3.5 C, -0.6 C from the station mean2009: 4.1 C, -0.1 C from the station mean2010: 4.3 C, +0.2 C from the station mean2011: 3.2 C, -0.9 C from the station mean2012: 4.2 C, +0.1 C from the station mean2013: 4.5 C, +0.4 C from the station mean2014: 4.8 C, +0.7 C from the station mean2015: 5.8 C, +1.7 C from the station mean2016: 4.9 C, +0.8 C from the station mean2017: 4.1 C, 0.0 C from the station mean2018: 4.7 C, +0.6 C from the station mean2019: 4.2 C, +0.1 C from the station mean2020: 4.5 C, +0.4 C from the station mean2021: 4.4 C, +0.3 C from the station mean2023: 5.2 C, +1.0 C from the station mean2024: 5.1 C, +1.0 C from the station mean2025: 5.3 C, +1.2 C from the station mean19891995200020052010201520202025
One stripe for each of 33 complete years at Thunder Basin, 1989 to 2025. Blue stripes are years cooler than the station's own mean of 4.1 C (39.4 F); red stripes are warmer. The coolest year was 1999, at 2.1 C (35.8 F), and the warmest was 2015, at 5.8 C (42.4 F). The strongest colour marks a difference of 2.1 C (3.8 F).
Annual mean temperature at Thunder Basin as warming stripes, 1989 to 2025
YearAnnual mean temperatureDifference from the station mean
19893.2 C-0.94 C
19903.6 C-0.56 C
19933.3 C-0.84 C
19944.0 C-0.16 C
19953.8 C-0.29 C
19962.7 C-1.39 C
19973.7 C-0.43 C
19984.6 C+0.49 C
19992.1 C-2.01 C
20003.0 C-1.14 C
20013.4 C-0.70 C
20023.6 C-0.50 C
20034.5 C+0.35 C
20054.8 C+0.64 C
20064.4 C+0.32 C
20074.2 C+0.05 C
20083.5 C-0.61 C
20094.1 C-0.06 C
20104.3 C+0.19 C
20113.2 C-0.89 C
20124.2 C+0.09 C
20134.5 C+0.39 C
20144.8 C+0.71 C
20155.8 C+1.67 C
20164.9 C+0.80 C
20174.1 C+0.03 C
20184.7 C+0.61 C
20194.2 C+0.07 C
20204.5 C+0.42 C
20214.4 C+0.28 C
20235.2 C+1.04 C
20245.1 C+0.99 C
20255.3 C+1.22 C

The annual mean temperature here has risen by 0.5 C (0.3 to 0.7) per decade over 1989 to 2025. In Fahrenheit: 0.9 F (0.6 to 1.3) per decade. The slope is a straight line fitted to 33 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at Thunder Basin
MeasurePer decade (C)Per decade (F)PeriodComplete yearsReading
Annual mean temperature0.5 C (0.3 to 0.7) per decade0.9 F (0.6 to 1.3) per decade1989 to 202533Rise
Mean daily maximum0.1 C (-0.2 to 0.3) per decade0.1 F (-0.3 to 0.5) per decade1989 to 202533Not clearly different from zero
Mean daily minimum1.0 C (0.8 to 1.2) per decade1.8 F (1.4 to 2.2) per decade1989 to 202533Rise

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

1988 to 2026
Yearly extremes at Thunder Basin: the record and the median year
MeasureRecordYear of the recordMedian yearYears with a value
Hottest day (TXx)35.4 C (95.7 F)202129.6 C (85.3 F)39
Coldest night (TNn)-32.7 C (-26.9 F)1990-22.1 C (-7.8 F)39
Wettest day (Rx1day)193.0 mm (7.6 in)200688.9 mm (3.5 in)39
Wettest five days (Rx5day)393.6 mm (15.5 in)2006182.9 mm (7.2 in)39
Longest dry spell (CDD)52 days200425 days39

Hottest day (TXx)

Hottest day (TXx) at Thunder Basin by year The hottest day of the year at Thunder Basin, 1988 to 2026. The record is 35.4 C (95.7 F) in 2021, marked on the chart; the median year is 29.6 C (85.3 F). 20253035401990200020102020Record: 35.4 C (95.7 F) in 2021
The hottest day of the year at Thunder Basin, 1988 to 2026. The record is 35.4 C (95.7 F) in 2021, marked on the chart; the median year is 29.6 C (85.3 F).
Hottest day (TXx) at Thunder Basin by year
YearHottest day (TXx)
198828.5 C (83.3 F)
198929.0 C (84.2 F)
199031.9 C (89.4 F)
199129.3 C (84.7 F)
199231.0 C (87.8 F)
199327.5 C (81.5 F)
199432.5 C (90.5 F)
199529.2 C (84.6 F)
199630.5 C (86.9 F)
199730.4 C (86.7 F)
199834.6 C (94.3 F)
199927.3 C (81.1 F)
200030.0 C (86.0 F)
200132.0 C (89.6 F)
200230.3 C (86.5 F)
200332.8 C (91.0 F)
200422.9 C (73.2 F)
200528.0 C (82.4 F)
200630.9 C (87.6 F)
200729.0 C (84.2 F)
200829.3 C (84.7 F)
200929.0 C (84.2 F)
201026.6 C (79.9 F)
201127.0 C (80.6 F)
201229.4 C (84.9 F)
201329.8 C (85.6 F)
201428.7 C (83.7 F)
201530.7 C (87.3 F)
201627.3 C (81.1 F)
201729.6 C (85.3 F)
201829.5 C (85.1 F)
201927.0 C (80.6 F)
202029.8 C (85.6 F)
202135.4 C (95.7 F)
202229.7 C (85.5 F)
202331.4 C (88.5 F)
202430.2 C (86.4 F)
202528.8 C (83.8 F)
202631.1 C (88.0 F)

Coldest night (TNn)

Coldest night (TNn) at Thunder Basin by year The coldest night of the year at Thunder Basin, 1988 to 2026. The record is -32.7 C (-26.9 F) in 1990, marked on the chart; the median year is -22.1 C (-7.8 F). -35-30-25-20-151990200020102020Record: -32.7 C (-26.9 F) in 1990
The coldest night of the year at Thunder Basin, 1988 to 2026. The record is -32.7 C (-26.9 F) in 1990, marked on the chart; the median year is -22.1 C (-7.8 F).
Coldest night (TNn) at Thunder Basin by year
YearColdest night (TNn)
1988-19.5 C (-3.1 F)
1989-29.6 C (-21.3 F)
1990-32.7 C (-26.9 F)
1991-20.0 C (-4.0 F)
1992-21.9 C (-7.4 F)
1993-25.1 C (-13.2 F)
1994-23.8 C (-10.8 F)
1995-21.9 C (-7.4 F)
1996-29.8 C (-21.6 F)
1997-24.0 C (-11.2 F)
1998-27.5 C (-17.5 F)
1999-18.7 C (-1.7 F)
2000-22.0 C (-7.6 F)
2001-22.2 C (-8.0 F)
2002-20.8 C (-5.4 F)
2003-21.1 C (-6.0 F)
2004-30.2 C (-22.4 F)
2005-18.1 C (-0.6 F)
2006-25.0 C (-13.0 F)
2007-22.1 C (-7.8 F)
2008-27.1 C (-16.8 F)
2009-22.9 C (-9.2 F)
2010-24.3 C (-11.7 F)
2011-21.1 C (-6.0 F)
2012-18.3 C (-0.9 F)
2013-22.7 C (-8.9 F)
2014-20.7 C (-5.3 F)
2015-15.4 C (4.3 F)
2016-21.9 C (-7.4 F)
2017-25.0 C (-13.0 F)
2018-21.8 C (-7.2 F)
2019-22.1 C (-7.8 F)
2020-16.7 C (1.9 F)
2021-28.0 C (-18.4 F)
2022-27.3 C (-17.1 F)
2023-20.3 C (-4.5 F)
2024-31.4 C (-24.5 F)
2025-20.8 C (-5.4 F)
2026-17.3 C (0.9 F)

Wettest day (Rx1day)

Wettest day (Rx1day) at Thunder Basin by year The wettest day of the year at Thunder Basin, 1988 to 2026. The record is 193.0 mm (7.6 in) in 2006, marked on the chart; the median year is 88.9 mm (3.5 in). 0501001502001990200020102020Record: 193.0 mm (7.6 in) in 2006
The wettest day of the year at Thunder Basin, 1988 to 2026. The record is 193.0 mm (7.6 in) in 2006, marked on the chart; the median year is 88.9 mm (3.5 in).
Wettest day (Rx1day) at Thunder Basin by year
YearWettest day (Rx1day)
198876.2 mm (3.0 in)
198999.1 mm (3.9 in)
1990127.0 mm (5.0 in)
199188.9 mm (3.5 in)
199250.8 mm (2.0 in)
199350.8 mm (2.0 in)
199496.5 mm (3.8 in)
199596.5 mm (3.8 in)
199676.2 mm (3.0 in)
199796.5 mm (3.8 in)
199871.1 mm (2.8 in)
199991.4 mm (3.6 in)
200055.9 mm (2.2 in)
200181.3 mm (3.2 in)
2002111.8 mm (4.4 in)
2003167.6 mm (6.6 in)
200491.4 mm (3.6 in)
200586.4 mm (3.4 in)
2006193.0 mm (7.6 in)
2007137.2 mm (5.4 in)
200881.3 mm (3.2 in)
2009119.4 mm (4.7 in)
201078.7 mm (3.1 in)
201176.2 mm (3.0 in)
201268.6 mm (2.7 in)
201396.5 mm (3.8 in)
201468.6 mm (2.7 in)
2015111.8 mm (4.4 in)
2016106.7 mm (4.2 in)
201799.1 mm (3.9 in)
201868.6 mm (2.7 in)
201981.3 mm (3.2 in)
202073.7 mm (2.9 in)
2021111.8 mm (4.4 in)
202286.4 mm (3.4 in)
2023101.6 mm (4.0 in)
202450.8 mm (2.0 in)
2025139.7 mm (5.5 in)
202648.3 mm (1.9 in)

Wettest five days (Rx5day)

Wettest five days (Rx5day) at Thunder Basin by year The wettest five days of the year at Thunder Basin, 1988 to 2026. The record is 393.6 mm (15.5 in) in 2006, marked on the chart; the median year is 182.9 mm (7.2 in). 1002003004001990200020102020Record: 393.6 mm (15.5 in) in 2006
The wettest five days of the year at Thunder Basin, 1988 to 2026. The record is 393.6 mm (15.5 in) in 2006, marked on the chart; the median year is 182.9 mm (7.2 in).
Wettest five days (Rx5day) at Thunder Basin by year
YearWettest five days (Rx5day)
1988154.9 mm (6.1 in)
1989221.0 mm (8.7 in)
1990348.0 mm (13.7 in)
1991180.3 mm (7.1 in)
1992147.3 mm (5.8 in)
1993132.1 mm (5.2 in)
1994149.8 mm (5.9 in)
1995264.2 mm (10.4 in)
1996180.3 mm (7.1 in)
1997200.6 mm (7.9 in)
1998162.7 mm (6.4 in)
1999228.6 mm (9.0 in)
2000104.2 mm (4.1 in)
2001185.4 mm (7.3 in)
2002203.3 mm (8.0 in)
2003330.2 mm (13.0 in)
2004152.4 mm (6.0 in)
2005170.2 mm (6.7 in)
2006393.6 mm (15.5 in)
2007218.5 mm (8.6 in)
2008127.0 mm (5.0 in)
2009292.0 mm (11.5 in)
2010160.0 mm (6.3 in)
2011205.9 mm (8.1 in)
2012177.7 mm (7.0 in)
2013182.9 mm (7.2 in)
2014208.3 mm (8.2 in)
2015249.0 mm (9.8 in)
2016177.7 mm (7.0 in)
2017289.6 mm (11.4 in)
2018134.6 mm (5.3 in)
2019144.8 mm (5.7 in)
2020175.3 mm (6.9 in)
2021243.8 mm (9.6 in)
2022185.3 mm (7.3 in)
2023203.1 mm (8.0 in)
2024132.1 mm (5.2 in)
2025284.4 mm (11.2 in)
2026137.1 mm (5.4 in)

Longest dry spell (CDD)

Longest dry spell (CDD) at Thunder Basin by year The longest dry spell of the year at Thunder Basin, 1988 to 2026. The record is 52 days in 2004, marked on the chart; the median year is 25 days. 02040601990200020102020Record: 52 days in 2004
The longest dry spell of the year at Thunder Basin, 1988 to 2026. The record is 52 days in 2004, marked on the chart; the median year is 25 days.
Longest dry spell (CDD) at Thunder Basin by year
YearLongest dry spell (CDD)
19886 days
198922 days
199041 days
199123 days
199223 days
199316 days
199435 days
199512 days
199625 days
199724 days
199829 days
199920 days
200019 days
200131 days
200232 days
200332 days
200452 days
200539 days
200629 days
200723 days
200820 days
200933 days
201038 days
201114 days
201229 days
201329 days
201421 days
201538 days
201622 days
201713 days
201834 days
201915 days
202028 days
202124 days
202222 days
202335 days
202428 days
202521 days
202634 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

33 years with a frost

Across 33 years with a frost, the median last spring frost at Thunder Basin falls on 14 June and the median first autumn frost on 16 September, which leaves a median of 101 days between them.

Fitted over all years, the growing season changes by +25.0 days per decade at this station.

Frost dates and growing season at Thunder Basin
MeasureMedian, all yearsEarliest periodRecent period (1994 to 2025)Recent against earliestFitted trend
Last spring frost14 Junen/a13 Junen/a-7.4 days per decade
First autumn frost16 Septembern/a18 Septembern/a+17.6 days per decade
Growing days101 daysn/a102 daysn/a+25.0 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

36 years, 1989 to 2025

A day with at least 88.3 mm (3.5 in) of rain is expected about once in 2 years. A day with at least 197.8 mm (7.8 in) of rain is expected about once in 100 years.

Rainfall return levels at Thunder Basin: the daily rain expected about once in a given number of years
Expected about once inA day with at leastNote
2 years88.3 mm (3.5 in)
5 years115.5 mm (4.5 in)
10 years134.4 mm (5.3 in)
25 years159.1 mm (6.3 in)
50 years178.2 mm (7.0 in)Longer than the 36 years of record
100 years197.8 mm (7.8 in)Longer than the 36 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, 36 years of values from 1989 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: 193.0 mm (7.6 in) in 2006; 167.6 mm (6.6 in) in 2003; 139.7 mm (5.5 in) in 2025.

Download the Data

  • Data for Thunder Basin standing records by year: CSV or JSON. Field meanings are on the data page.
  • Data for Thunder Basin threshold days by year: CSV or JSON. Field meanings are on the data page.

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 2026-10-16 (16 October 2026). Records are computed by this site and are not official.

Data as of . Last revised (2026-10-17).