Built 2026-10-16 (16 October 2026)

Fossil Butte Weather Records (USC00483582)

Record envelope, standing records and threshold days for Fossil Butte (USC00483582), Wyoming, United States, with 37 years of record.

Key Facts for Fossil Butte

  • Fossil Butte (USC00483582) is a weather station in Wyoming, United States at 41.84 latitude and -110.77 longitude, 2,068 m (6,786 ft) above sea level.
  • The station reports from 1990 to 2026, 37 years of record.
  • 1,464 records set at Fossil Butte still stand.
  • Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
  • Fossil Butte set a daily record high minimum temperature of 6.7 C (44.1 F) on 11 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, 41.84 latitude, -110.77 longitude.
  • Elevation: 2,068 m (6,786 ft).
  • Period of record: 1990 to 2026, 37 years.
  • Eligible elements: tmax, tmin, prcp, snow, snwd.

Daily Record Envelope and 2026

42 days at or beyond a record
Daily record high and record low at Fossil Butte, with 2026 drawn through them The band shows the record high and record low for each calendar day at Fossil Butte. The lines show the 2026 daily maximum and minimum. 42 days in 2026 matched or passed a record. Temperatures are in degrees Celsius. -60-40-200204060 JanFebMarAprMayJunJulAugSepOctNovDec
The band shows the record high and record low for each calendar day at Fossil Butte. The lines show the 2026 daily maximum and minimum. 42 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.
Daily record high and record low at Fossil Butte, with 2026 drawn through them
MonthHighest record highLowest record low2026 highest maximum2026 lowest minimum
Jan11.7 C (53.1 F)-38.9 C (-38.0 F)5.6 C (42.1 F)-23.9 C (-11.0 F)
Feb12.8 C (55.0 F)-36.1 C (-33.0 F)10.6 C (51.1 F)-18.9 C (-2.0 F)
Mar23.3 C (73.9 F)-30.0 C (-22.0 F)23.3 C (73.9 F)-10.6 C (12.9 F)
Apr25.0 C (77.0 F)-22.2 C (-8.0 F)22.2 C (72.0 F)-13.3 C (8.1 F)
May31.7 C (89.1 F)-13.3 C (8.1 F)27.2 C (81.0 F)-8.3 C (17.1 F)
Jun33.3 C (91.9 F)-10.6 C (12.9 F)30.6 C (87.1 F)-4.4 C (24.1 F)
Jul42.8 C (109.0 F)-3.9 C (25.0 F)36.1 C (97.0 F)-0.6 C (30.9 F)
Aug35.6 C (96.1 F)-6.1 C (21.0 F)35.0 C (95.0 F)-1.1 C (30.0 F)
Sep34.4 C (93.9 F)-12.2 C (10.0 F)27.8 C (82.0 F)-3.3 C (26.1 F)
Oct27.2 C (81.0 F)-31.1 C (-24.0 F)26.1 C (79.0 F)-2.2 C (28.0 F)
Nov19.4 C (66.9 F)-30.6 C (-23.1 F)n/an/a
Dec13.9 C (57.0 F)-42.8 C (-45.0 F)n/an/a

Which Years Hold Standing Records

1,464 standing records
Standing records at Fossil Butte by the year they were set 1,464 records at Fossil Butte still stand. 2015 holds the most, with 61. 0204060801990: 261991: 391992: 441993: 591994: 401995: 471996: 531997: 411998: 231999: 552000: 452001: 392002: 412003: 552004: 272005: 242006: 332007: 292008: 442009: 332010: 322011: 262012: 492013: 422014: 412015: 612016: 272017: 422018: 302019: 452020: 322021: 362022: 372023: 492024: 232025: 502026: 451990199419982002200620102014201820222026
1,464 records at Fossil Butte still stand. 2015 holds the most, with 61.
Standing records at Fossil Butte by the year they were set
Year setStanding records
199026
199139
199244
199359
199440
199547
199653
199741
199823
199955
200045
200139
200241
200355
200427
200524
200633
200729
200844
200933
201032
201126
201249
201342
201441
201561
201627
201742
201830
201945
202032
202136
202237
202349
202423
202550
202645

All-Time Record Progression

2 new records
When Fossil Butte set new all-time records 2 all-time records were set at Fossil Butte between 4 April 2023 and 5 April 2023. Each dot is a new record. Record daily snowfallRecord snow depth4 April 2023: Record daily snowfall 46.2 cm (18.2 in)5 April 2023: Record snow depth 101.6 cm (40.0 in)
2 all-time records were set at Fossil Butte between 4 April 2023 and 5 April 2023. Each dot is a new record.
When Fossil Butte set new all-time records
DateKindDetail
2023-04-04Record daily snowfallRecord daily snowfall 46.2 cm (18.2 in)
2023-04-05Record snow depthRecord snow depth 101.6 cm (40.0 in)

Wettest Day of Each Month

May: 61.0 mm (2.4 in)
Record daily precipitation for each month at Fossil Butte The wettest day on record for each calendar month at Fossil Butte. The most was 61.0 mm (2.4 in) on 31 May 1999. 020406080 Jan: 17.8 mm (0.7 in), 10 January 2005 Jan Feb: 14.0 mm (0.6 in), 7 February 2017 Feb Mar: 29.0 mm (1.1 in), 23 March 2017 Mar Apr: 40.9 mm (1.6 in), 28 April 2005 Apr May: 61.0 mm (2.4 in), 31 May 1999 May Jun: 27.4 mm (1.1 in), 17 June 2020 Jun Jul: 35.3 mm (1.4 in), 30 July 1999 Jul Aug: 30.5 mm (1.2 in), 3 August 2023 Aug Sep: 44.2 mm (1.7 in), 28 September 2014 Sep Oct: 27.2 mm (1.1 in), 23 October 2012 Oct Nov: 33.8 mm (1.3 in), 17 November 2017 Nov Dec: 14.0 mm (0.6 in), 19 December 2013 Dec
The wettest day on record for each calendar month at Fossil Butte. The most was 61.0 mm (2.4 in) on 31 May 1999.
Record daily precipitation for each month at Fossil Butte
MonthRecord daily precipitation (mm)Date
Jan17.8 mm (0.7 in)10 January 2005
Feb14.0 mm (0.6 in)7 February 2017
Mar29.0 mm (1.1 in)23 March 2017
Apr40.9 mm (1.6 in)28 April 2005
May61.0 mm (2.4 in)31 May 1999
Jun27.4 mm (1.1 in)17 June 2020
Jul35.3 mm (1.4 in)30 July 1999
Aug30.5 mm (1.2 in)3 August 2023
Sep44.2 mm (1.7 in)28 September 2014
Oct27.2 mm (1.1 in)23 October 2012
Nov33.8 mm (1.3 in)17 November 2017
Dec14.0 mm (0.6 in)19 December 2013

Period of Record Coverage

1990 to 2026
Days with data per year at Fossil Butte 37 years of record at Fossil Butte, 1990 to 2026. 5 years have data for under 90 percent of days and are left out of rankings: 1990, 1992, 1998, 1999, 2026. 1990: 149 of 365 days1991: 358 of 365 days1992: 321 of 366 days1993: 343 of 365 days1994: 362 of 365 days1995: 354 of 365 days1996: 360 of 366 days1997: 357 of 365 days1998: 320 of 365 days1999: 314 of 365 days2000: 343 of 366 days2001: 337 of 365 days2002: 351 of 365 days2003: 357 of 365 days2004: 356 of 366 days2005: 356 of 365 days2006: 354 of 365 days2007: 354 of 365 days2008: 353 of 366 days2009: 360 of 365 days2010: 361 of 365 days2011: 362 of 365 days2012: 361 of 366 days2013: 344 of 365 days2014: 365 of 365 days2015: 364 of 365 days2016: 363 of 366 days2017: 365 of 365 days2018: 355 of 365 days2019: 365 of 365 days2020: 366 of 366 days2021: 365 of 365 days2022: 363 of 365 days2023: 353 of 365 days2024: 366 of 366 days2025: 365 of 365 days2026: 284 of 365 days19901995200020052010201520202025
37 years of record at Fossil Butte, 1990 to 2026. 5 years have data for under 90 percent of days and are left out of rankings: 1990, 1992, 1998, 1999, 2026.
Days with data per year at Fossil Butte
YearDays with dataShare of yearComplete
199014941%No
199135898%Yes
199232188%No
199334394%Yes
199436299%Yes
199535497%Yes
199636098%Yes
199735798%Yes
199832088%No
199931486%No
200034394%Yes
200133792%Yes
200235196%Yes
200335798%Yes
200435697%Yes
200535698%Yes
200635497%Yes
200735497%Yes
200835396%Yes
200936099%Yes
201036199%Yes
201136299%Yes
201236199%Yes
201334494%Yes
2014365100%Yes
2015364100%Yes
201636399%Yes
2017365100%Yes
201835597%Yes
2019365100%Yes
2020366100%Yes
2021365100%Yes
202236399%Yes
202335397%Yes
2024366100%Yes
2025365100%Yes
202628478%No

Latest Records

20
Latest records at Fossil Butte
DateStationRecordValueBeat old record byOld record stoodSignificance
11 October 2026Fossil Butte, USdaily high min (Provisional)6.7 C (44.1 F)1.1 C (2.0 F)0 years5 of 100 (Routine)
10 October 2026Fossil Butte, USmonthly high min (Tie, Provisional)8.9 C (48.0 F)tie11 years4 of 100 (Routine)
7 October 2026Fossil Butte, USdaily high max (Provisional)24.4 C (75.9 F)1.1 C (2.0 F)5 years5 of 100 (Routine)
6 October 2026Fossil Butte, USdaily high max (Provisional)26.1 C (79.0 F)1.7 C (3.1 F)32 years14 of 100 (Routine)
5 October 2026Fossil Butte, USdaily high max (Tie, Provisional)26.1 C (79.0 F)tie1 year0 of 100 (Routine)
22 September 2026Fossil Butte, USdaily high min (Provisional)8.3 C (46.9 F)0.5 C (0.9 F)12 years7 of 100 (Routine)
18 September 2026Fossil Butte, USdaily rain (Provisional)22.6 mm (0.9 in)12.2 mm (0.5 in)32 years20 of 100 (Routine)
17 September 2026Fossil Butte, USdaily high min (Provisional)11.1 C (52.0 F)3.9 C (7.0 F)24 years18 of 100 (Routine)
29 August 2026Fossil Butte, USdaily rain (Provisional)18.8 mm (0.7 in)0.8 mm (0.03 in)15 years8 of 100 (Routine)
27 August 2026Fossil Butte, USdaily high max (Provisional)32.2 C (90.0 F)0.5 C (0.9 F)24 years11 of 100 (Routine)
21 August 2026Fossil Butte, USdaily high max (Provisional)33.3 C (91.9 F)0.5 C (0.9 F)0 years4 of 100 (Routine)
15 August 2026Fossil Butte, USdaily low max (Tie)24.4 C (75.9 F)tie32 years3 of 100 (Routine)
10 August 2026Fossil Butte, USdaily high max (Tie)33.9 C (93.0 F)tie23 years2 of 100 (Routine)
9 August 2026Fossil Butte, USdaily high max (Tie)33.3 C (91.9 F)tie13 years1 of 100 (Routine)
8 August 2026Fossil Butte, USdaily high max (Tie)33.9 C (93.0 F)tie36 years3 of 100 (Routine)
7 August 2026Fossil Butte, USdaily high max35.0 C (95.0 F)2.2 C (4.0 F)36 years20 of 100 (Routine)
6 August 2026Fossil Butte, USdaily low min-0.6 C (30.9 F)2.3 C (4.1 F)25 years15 of 100 (Routine)
5 August 2026Fossil Butte, USdaily low min-1.1 C (30.0 F)1.1 C (2.0 F)29 years13 of 100 (Routine)
1 August 2026Fossil Butte, USdaily high max (Tie)35.0 C (95.0 F)tie25 years2 of 100 (Routine)
27 July 2026Fossil Butte, USdaily high min16.7 C (62.1 F)2.3 C (4.1 F)7 years11 of 100 (Routine)

Climate Trend

31 complete years, 1991 to 2025
Annual mean temperature at Fossil Butte as warming stripes, 1991 to 2025 One stripe for each of 31 complete years at Fossil Butte, 1991 to 2025. Blue stripes are years cooler than the station's own mean of 4.2 C (39.5 F); red stripes are warmer. The coolest year was 1993, at 2.1 C (35.7 F), and the warmest was 2025, at 6.0 C (42.7 F). The strongest colour marks a difference of 2.2 C (4.0 F). 1991: 3.6 C, -0.6 C from the station mean1993: 2.1 C, -2.1 C from the station mean1994: 4.5 C, +0.3 C from the station mean1995: 4.4 C, +0.2 C from the station mean1996: 4.2 C, +0.1 C from the station mean1997: 3.4 C, -0.8 C from the station mean2000: 4.4 C, +0.2 C from the station mean2001: 4.2 C, 0.0 C from the station mean2002: 3.5 C, -0.7 C from the station mean2003: 5.2 C, +1.0 C from the station mean2004: 3.9 C, -0.3 C from the station mean2005: 3.5 C, -0.7 C from the station mean2006: 4.1 C, -0.1 C from the station mean2007: 4.9 C, +0.7 C from the station mean2008: 2.9 C, -1.3 C from the station mean2009: 3.8 C, -0.4 C from the station mean2010: 4.2 C, 0.0 C from the station mean2011: 3.0 C, -1.2 C from the station mean2012: 5.5 C, +1.3 C from the station mean2014: 5.1 C, +0.9 C from the station mean2015: 5.8 C, +1.6 C from the station mean2016: 4.7 C, +0.6 C from the station mean2017: 4.6 C, +0.4 C from the station mean2018: 4.9 C, +0.7 C from the station mean2019: 2.7 C, -1.4 C from the station mean2020: 3.9 C, -0.3 C from the station mean2021: 5.5 C, +1.3 C from the station mean2022: 3.7 C, -0.4 C from the station mean2023: 2.6 C, -1.6 C from the station mean2024: 5.0 C, +0.8 C from the station mean2025: 6.0 C, +1.8 C from the station mean19911995200020052010201520202025
One stripe for each of 31 complete years at Fossil Butte, 1991 to 2025. Blue stripes are years cooler than the station's own mean of 4.2 C (39.5 F); red stripes are warmer. The coolest year was 1993, at 2.1 C (35.7 F), and the warmest was 2025, at 6.0 C (42.7 F). The strongest colour marks a difference of 2.2 C (4.0 F).
Annual mean temperature at Fossil Butte as warming stripes, 1991 to 2025
YearAnnual mean temperatureDifference from the station mean
19913.6 C-0.59 C
19932.1 C-2.13 C
19944.5 C+0.35 C
19954.4 C+0.19 C
19964.2 C+0.06 C
19973.4 C-0.81 C
20004.4 C+0.24 C
20014.2 C-0.03 C
20023.5 C-0.67 C
20035.2 C+1.04 C
20043.9 C-0.27 C
20053.5 C-0.72 C
20064.1 C-0.11 C
20074.9 C+0.75 C
20082.9 C-1.28 C
20093.8 C-0.37 C
20104.2 C0.00 C
20113.0 C-1.22 C
20125.5 C+1.31 C
20145.1 C+0.88 C
20155.8 C+1.59 C
20164.7 C+0.56 C
20174.6 C+0.41 C
20184.9 C+0.75 C
20192.7 C-1.44 C
20203.9 C-0.26 C
20215.5 C+1.29 C
20223.7 C-0.44 C
20232.6 C-1.55 C
20245.0 C+0.81 C
20256.0 C+1.79 C

The fitted trend in annual mean temperature here over 1991 to 2025 is 0.3 C (-0.1 to 0.6) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.5 F (-0.1 to 1.1) per decade. The slope is a straight line fitted to 31 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at Fossil Butte
MeasurePer decade (C)Per decade (F)PeriodComplete yearsReading
Annual mean temperature0.3 C (-0.1 to 0.6) per decade0.5 F (-0.1 to 1.1) per decade1991 to 202531Not clearly different from zero
Mean daily maximum0.3 C (-0.1 to 0.8) per decade0.6 F (-0.2 to 1.4) per decade1991 to 202531Not clearly different from zero
Mean daily minimum0.2 C (-0.1 to 0.5) per decade0.4 F (-0.1 to 1.0) per decade1991 to 202531Not 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

1990 to 2026
Yearly extremes at Fossil Butte: the record and the median year
MeasureRecordYear of the recordMedian yearYears with a value
Hottest day (TXx)42.8 C (109.0 F)199933.9 C (93.0 F)37
Coldest night (TNn)-42.8 C (-45.0 F)1990-32.2 C (-26.0 F)37
Wettest day (Rx1day)61.0 mm (2.4 in)199923.6 mm (0.9 in)37
Wettest five days (Rx5day)79.1 mm (3.1 in)201434.3 mm (1.4 in)37
Longest dry spell (CDD)48 days201629 days37

Hottest day (TXx)

Hottest day (TXx) at Fossil Butte by year The hottest day of the year at Fossil Butte, 1990 to 2026. The record is 42.8 C (109.0 F) in 1999, marked on the chart; the median year is 33.9 C (93.0 F). 25303540451990200020102020Record: 42.8 C (109.0 F) in 1999
The hottest day of the year at Fossil Butte, 1990 to 2026. The record is 42.8 C (109.0 F) in 1999, marked on the chart; the median year is 33.9 C (93.0 F).
Hottest day (TXx) at Fossil Butte by year
YearHottest day (TXx)
199033.9 C (93.0 F)
199131.7 C (89.1 F)
199232.2 C (90.0 F)
199328.9 C (84.0 F)
199433.3 C (91.9 F)
199533.3 C (91.9 F)
199633.3 C (91.9 F)
199731.7 C (89.1 F)
199833.3 C (91.9 F)
199942.8 C (109.0 F)
200038.3 C (100.9 F)
200134.4 C (93.9 F)
200236.7 C (98.1 F)
200335.6 C (96.1 F)
200432.2 C (90.0 F)
200533.9 C (93.0 F)
200634.4 C (93.9 F)
200735.0 C (95.0 F)
200832.8 C (91.0 F)
200933.9 C (93.0 F)
201032.8 C (91.0 F)
201132.2 C (90.0 F)
201233.9 C (93.0 F)
201333.3 C (91.9 F)
201433.3 C (91.9 F)
201532.8 C (91.0 F)
201633.9 C (93.0 F)
201732.2 C (90.0 F)
201834.4 C (93.9 F)
201933.3 C (91.9 F)
202034.4 C (93.9 F)
202134.4 C (93.9 F)
202235.6 C (96.1 F)
202333.9 C (93.0 F)
202435.0 C (95.0 F)
202535.0 C (95.0 F)
202636.1 C (97.0 F)

Coldest night (TNn)

Coldest night (TNn) at Fossil Butte by year The coldest night of the year at Fossil Butte, 1990 to 2026. The record is -42.8 C (-45.0 F) in 1990, marked on the chart; the median year is -32.2 C (-26.0 F). -45-40-35-30-25-201990200020102020Record: -42.8 C (-45.0 F) in 1990
The coldest night of the year at Fossil Butte, 1990 to 2026. The record is -42.8 C (-45.0 F) in 1990, marked on the chart; the median year is -32.2 C (-26.0 F).
Coldest night (TNn) at Fossil Butte by year
YearColdest night (TNn)
1990-42.8 C (-45.0 F)
1991-30.6 C (-23.1 F)
1992-30.0 C (-22.0 F)
1993-30.6 C (-23.1 F)
1994-30.6 C (-23.1 F)
1995-31.1 C (-24.0 F)
1996-30.6 C (-23.1 F)
1997-32.2 C (-26.0 F)
1998-32.8 C (-27.0 F)
1999-25.6 C (-14.1 F)
2000-25.6 C (-14.1 F)
2001-35.0 C (-31.0 F)
2002-37.8 C (-36.0 F)
2003-31.1 C (-24.0 F)
2004-30.6 C (-23.1 F)
2005-40.0 C (-40.0 F)
2006-30.0 C (-22.0 F)
2007-32.2 C (-26.0 F)
2008-33.3 C (-27.9 F)
2009-34.4 C (-29.9 F)
2010-31.1 C (-24.0 F)
2011-36.1 C (-33.0 F)
2012-29.4 C (-20.9 F)
2013-33.9 C (-29.0 F)
2014-36.1 C (-33.0 F)
2015-34.4 C (-29.9 F)
2016-32.2 C (-26.0 F)
2017-38.9 C (-38.0 F)
2018-33.9 C (-29.0 F)
2019-35.6 C (-32.1 F)
2020-32.2 C (-26.0 F)
2021-27.2 C (-17.0 F)
2022-31.1 C (-24.0 F)
2023-35.0 C (-31.0 F)
2024-27.2 C (-17.0 F)
2025-30.0 C (-22.0 F)
2026-23.9 C (-11.0 F)

Wettest day (Rx1day)

Wettest day (Rx1day) at Fossil Butte by year The wettest day of the year at Fossil Butte, 1990 to 2026. The record is 61.0 mm (2.4 in) in 1999, marked on the chart; the median year is 23.6 mm (0.9 in). 0204060801990200020102020Record: 61.0 mm (2.4 in) in 1999
The wettest day of the year at Fossil Butte, 1990 to 2026. The record is 61.0 mm (2.4 in) in 1999, marked on the chart; the median year is 23.6 mm (0.9 in).
Wettest day (Rx1day) at Fossil Butte by year
YearWettest day (Rx1day)
19905.8 mm (0.23 in)
199125.4 mm (1.0 in)
199219.1 mm (0.8 in)
199324.9 mm (1.0 in)
199421.1 mm (0.8 in)
199521.8 mm (0.9 in)
199618.8 mm (0.7 in)
199715.0 mm (0.6 in)
199823.9 mm (0.9 in)
199961.0 mm (2.4 in)
200023.6 mm (0.9 in)
200125.4 mm (1.0 in)
200216.5 mm (0.6 in)
200324.1 mm (0.9 in)
200416.8 mm (0.7 in)
200540.9 mm (1.6 in)
200619.8 mm (0.8 in)
200718.5 mm (0.7 in)
200817.0 mm (0.7 in)
200925.4 mm (1.0 in)
201024.1 mm (0.9 in)
201127.4 mm (1.1 in)
201227.2 mm (1.1 in)
201315.2 mm (0.6 in)
201444.2 mm (1.7 in)
201518.3 mm (0.7 in)
201639.9 mm (1.6 in)
201733.8 mm (1.3 in)
201812.2 mm (0.5 in)
201919.1 mm (0.8 in)
202027.4 mm (1.1 in)
202117.8 mm (0.7 in)
202214.5 mm (0.6 in)
202330.5 mm (1.2 in)
202418.8 mm (0.7 in)
202524.1 mm (0.9 in)
202635.3 mm (1.4 in)

Wettest five days (Rx5day)

Wettest five days (Rx5day) at Fossil Butte by year The wettest five days of the year at Fossil Butte, 1990 to 2026. The record is 79.1 mm (3.1 in) in 2014, marked on the chart; the median year is 34.3 mm (1.4 in). 0204060801990200020102020Record: 79.1 mm (3.1 in) in 2014
The wettest five days of the year at Fossil Butte, 1990 to 2026. The record is 79.1 mm (3.1 in) in 2014, marked on the chart; the median year is 34.3 mm (1.4 in).
Wettest five days (Rx5day) at Fossil Butte by year
YearWettest five days (Rx5day)
19907.6 mm (0.30 in)
199126.4 mm (1.0 in)
199234.6 mm (1.4 in)
199339.1 mm (1.5 in)
199443.8 mm (1.7 in)
199537.5 mm (1.5 in)
199629.2 mm (1.1 in)
199722.9 mm (0.9 in)
199860.2 mm (2.4 in)
199934.3 mm (1.4 in)
200023.1 mm (0.9 in)
200119.6 mm (0.8 in)
200222.3 mm (0.9 in)
200325.7 mm (1.0 in)
200435.8 mm (1.4 in)
200570.6 mm (2.8 in)
200633.8 mm (1.3 in)
200729.7 mm (1.2 in)
200817.2 mm (0.7 in)
200931.0 mm (1.2 in)
201034.5 mm (1.4 in)
201134.0 mm (1.3 in)
201233.2 mm (1.3 in)
201323.2 mm (0.9 in)
201479.1 mm (3.1 in)
201539.6 mm (1.6 in)
201668.3 mm (2.7 in)
201735.6 mm (1.4 in)
201835.6 mm (1.4 in)
201941.5 mm (1.6 in)
202029.0 mm (1.1 in)
202137.1 mm (1.5 in)
202222.8 mm (0.9 in)
202338.3 mm (1.5 in)
202434.6 mm (1.4 in)
202526.7 mm (1.1 in)
202643.1 mm (1.7 in)

Longest dry spell (CDD)

Longest dry spell (CDD) at Fossil Butte by year The longest dry spell of the year at Fossil Butte, 1990 to 2026. The record is 48 days in 2016, marked on the chart; the median year is 29 days. 02040601990200020102020Record: 48 days in 2016
The longest dry spell of the year at Fossil Butte, 1990 to 2026. The record is 48 days in 2016, marked on the chart; the median year is 29 days.
Longest dry spell (CDD) at Fossil Butte by year
YearLongest dry spell (CDD)
199029 days
199126 days
199234 days
199326 days
199444 days
199528 days
199630 days
199727 days
199824 days
19997 days
20008 days
200135 days
200232 days
200328 days
200426 days
200533 days
200625 days
200738 days
200833 days
200932 days
201027 days
201128 days
201220 days
201329 days
201423 days
201536 days
201648 days
201743 days
201841 days
201927 days
202032 days
202129 days
202231 days
202326 days
202429 days
202545 days
202625 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

31 years with a frost

Across 31 years with a frost, the median last spring frost at Fossil Butte falls on 24 June and the median first autumn frost on 31 July, which leaves a median of 37 days between them.

Fitted over all years, the growing season changes by +7.5 days per decade at this station.

Frost dates and growing season at Fossil Butte
MeasureMedian, all yearsEarliest periodRecent period (1993 to 2025)Recent against earliestFitted trend
Last spring frost24 Junen/a25 Junen/a-1.4 days per decade
First autumn frost31 Julyn/a3 Augustn/a+6.1 days per decade
Growing days37 daysn/a41 daysn/a+7.5 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

30 years, 1991 to 2025

A day with at least 21.5 mm (0.8 in) of rain is expected about once in 2 years. A day with at least 53.6 mm (2.1 in) of rain is expected about once in 100 years.

Rainfall return levels at Fossil Butte: the daily rain expected about once in a given number of years
Expected about once inA day with at leastNote
2 years21.5 mm (0.8 in)
5 years28.6 mm (1.1 in)
10 years33.8 mm (1.3 in)
25 years41.1 mm (1.6 in)
50 years47.1 mm (1.9 in)Longer than the 30 years of record
100 years53.6 mm (2.1 in)Longer than the 30 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, 30 years of values from 1991 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: 44.2 mm (1.7 in) in 2014; 40.9 mm (1.6 in) in 2005; 39.9 mm (1.6 in) in 2016.

Download the Data

  • Data for Fossil Butte standing records by year: CSV or JSON. Field meanings are on the data page.
  • Data for Fossil Butte 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 2026-10-14 (14 October 2026). Records are computed by this site and are not official.

Data as of . Last revised (2026-10-14).