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Keystone Dam Weather Records (USC00344812)

Record envelope, standing records and threshold days for Keystone Dam (USC00344812), Oklahoma, United States, with 41 years of record.

Key Facts for Keystone Dam

  • Keystone Dam (USC00344812) is a weather station in Oklahoma, United States at 36.15 latitude and -96.25 longitude, 215 m (705 ft) above sea level.
  • The station reports from 1957 to 1997, 41 years of record.
  • 1,464 records set at Keystone Dam still stand.
  • Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
  • Keystone Dam set a daily record low minimum temperature of -3.3 C (26.1 F) on 15 April 1997.

About the Station

  • Location: Oklahoma, United States, 36.15 latitude, -96.25 longitude.
  • Elevation: 215 m (705 ft).
  • Period of record: 1957 to 1997, 41 years.
  • Eligible elements: tmax, tmin, prcp, snow, snwd.

Daily Record Envelope and 2026

0 days at or beyond a record
Daily record high and record low at Keystone Dam, with 2026 drawn through them The band shows the record high and record low for each calendar day at Keystone Dam. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius. -40-200204060 JanFebMarAprMayJunJulAugSepOctNovDec
The band shows the record high and record low for each calendar day at Keystone Dam. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.
Daily record high and record low at Keystone Dam, with 2026 drawn through them
MonthHighest record highLowest record low2026 highest maximum2026 lowest minimum
Jan26.1 C (79.0 F)-22.2 C (-8.0 F)n/an/a
Feb32.8 C (91.0 F)-23.9 C (-11.0 F)n/an/a
Mar33.3 C (91.9 F)-17.8 C (0.0 F)n/an/a
Apr37.8 C (100.0 F)-6.7 C (19.9 F)n/an/a
May36.1 C (97.0 F)1.1 C (34.0 F)n/an/a
Jun37.8 C (100.0 F)5.6 C (42.1 F)n/an/a
Jul43.3 C (109.9 F)7.2 C (45.0 F)n/an/a
Aug43.3 C (109.9 F)7.8 C (46.0 F)n/an/a
Sep40.6 C (105.1 F)-1.7 C (28.9 F)n/an/a
Oct36.1 C (97.0 F)-6.1 C (21.0 F)n/an/a
Nov30.0 C (86.0 F)-17.2 C (1.0 F)n/an/a
Dec26.7 C (80.1 F)-21.7 C (-7.1 F)n/an/a

Which Years Hold Standing Records

1,464 standing records
Standing records at Keystone Dam by the year they were set 1,464 records at Keystone Dam still stand. 1980 holds the most, with 61. 0204060801957: 51958: 151959: 351960: 291961: 391962: 491963: 581964: 541965: 501966: 541967: 411968: 331969: 201970: 501971: 451972: 441973: 201974: 411975: 371976: 511977: 411978: 561979: 321980: 611981: 271982: 261983: 361984: 301985: 321986: 341987: 281988: 191989: 481990: 381991: 301992: 321993: 261994: 251995: 271996: 341997: 12195719621967197219771982198719921997
1,464 records at Keystone Dam still stand. 1980 holds the most, with 61.
Standing records at Keystone Dam by the year they were set
Year setStanding records
19575
195815
195935
196029
196139
196249
196358
196454
196550
196654
196741
196833
196920
197050
197145
197244
197320
197441
197537
197651
197741
197856
197932
198061
198127
198226
198336
198430
198532
198634
198728
198819
198948
199038
199130
199232
199326
199425
199527
199634
199712

All-Time Record Progression

2 new records
When Keystone Dam set new all-time records 2 all-time records were set at Keystone Dam between 7 January 1988 and 6 March 1989. Each dot is a new record. Record daily snowfallRecord snow depth7 January 1988: Record daily snowfall 25.4 cm (10.0 in)6 March 1989: Record snow depth 22.9 cm (9.0 in)1990
2 all-time records were set at Keystone Dam between 7 January 1988 and 6 March 1989. Each dot is a new record.
When Keystone Dam set new all-time records
DateKindDetail
1988-01-07Record daily snowfallRecord daily snowfall 25.4 cm (10.0 in)
1989-03-06Record snow depthRecord snow depth 22.9 cm (9.0 in)

Wettest Day of Each Month

Sep: 154.2 mm (6.1 in)
Record daily precipitation for each month at Keystone Dam The wettest day on record for each calendar month at Keystone Dam. The most was 154.2 mm (6.1 in) on 30 September 1986. 050100150200 Jan: 62.7 mm (2.5 in), 31 January 1975 Jan Feb: 123.7 mm (4.9 in), 23 February 1985 Feb Mar: 92.5 mm (3.6 in), 12 March 1990 Mar Apr: 79.0 mm (3.1 in), 30 April 1985 Apr May: 147.3 mm (5.8 in), 12 May 1982 May Jun: 104.4 mm (4.1 in), 10 June 1995 Jun Jul: 130.8 mm (5.1 in), 4 July 1960 Jul Aug: 93.7 mm (3.7 in), 15 August 1969 Aug Sep: 154.2 mm (6.1 in), 30 September 1986 Sep Oct: 106.9 mm (4.2 in), 22 October 1972 Oct Nov: 104.1 mm (4.1 in), 3 November 1974 Nov Dec: 59.4 mm (2.3 in), 24 December 1965 Dec
The wettest day on record for each calendar month at Keystone Dam. The most was 154.2 mm (6.1 in) on 30 September 1986.
Record daily precipitation for each month at Keystone Dam
MonthRecord daily precipitation (mm)Date
Jan62.7 mm (2.5 in)31 January 1975
Feb123.7 mm (4.9 in)23 February 1985
Mar92.5 mm (3.6 in)12 March 1990
Apr79.0 mm (3.1 in)30 April 1985
May147.3 mm (5.8 in)12 May 1982
Jun104.4 mm (4.1 in)10 June 1995
Jul130.8 mm (5.1 in)4 July 1960
Aug93.7 mm (3.7 in)15 August 1969
Sep154.2 mm (6.1 in)30 September 1986
Oct106.9 mm (4.2 in)22 October 1972
Nov104.1 mm (4.1 in)3 November 1974
Dec59.4 mm (2.3 in)24 December 1965

Period of Record Coverage

1957 to 1997
Days with data per year at Keystone Dam 41 years of record at Keystone Dam, 1957 to 1997. 26 years have data for under 90 percent of days and are left out of rankings: 1957, 1958, 1959, 1960, 1961, 1962, 1963, 1964 and others. 1957: 64 of 365 days1958: 159 of 365 days1959: 237 of 365 days1960: 224 of 366 days1961: 261 of 365 days1962: 308 of 365 days1963: 267 of 365 days1964: 283 of 366 days1965: 318 of 365 days1966: 339 of 365 days1967: 351 of 365 days1968: 325 of 366 days1969: 349 of 365 days1970: 339 of 365 days1971: 360 of 365 days1972: 339 of 366 days1973: 352 of 365 days1974: 357 of 365 days1975: 350 of 365 days1976: 351 of 366 days1977: 353 of 365 days1978: 323 of 365 days1979: 306 of 365 days1980: 322 of 366 days1981: 325 of 365 days1982: 304 of 365 days1983: 294 of 365 days1984: 314 of 366 days1985: 324 of 365 days1986: 340 of 365 days1987: 316 of 365 days1988: 317 of 366 days1989: 311 of 365 days1990: 351 of 365 days1991: 293 of 365 days1992: 343 of 366 days1993: 308 of 365 days1994: 327 of 365 days1995: 325 of 365 days1996: 341 of 366 days1997: 94 of 365 days1960197019801990
41 years of record at Keystone Dam, 1957 to 1997. 26 years have data for under 90 percent of days and are left out of rankings: 1957, 1958, 1959, 1960, 1961, 1962, 1963, 1964 and others.
Days with data per year at Keystone Dam
YearDays with dataShare of yearComplete
19576418%No
195815944%No
195923765%No
196022461%No
196126172%No
196230884%No
196326773%No
196428377%No
196531887%No
196633993%Yes
196735196%Yes
196832589%No
196934996%Yes
197033993%Yes
197136099%Yes
197233993%Yes
197335296%Yes
197435798%Yes
197535096%Yes
197635196%Yes
197735397%Yes
197832388%No
197930684%No
198032288%No
198132589%No
198230483%No
198329481%No
198431486%No
198532489%No
198634093%Yes
198731687%No
198831787%No
198931185%No
199035196%Yes
199129380%No
199234394%Yes
199330884%No
199432790%No
199532589%No
199634193%Yes
19979426%No

Latest Records

20
Latest records at Keystone Dam
DateStationRecordValueBeat old record byOld record stoodSignificance
15 April 1997Keystone Dam, USdaily low min-3.3 C (26.1 F)1.1 C (2.0 F)14 years10 of 100 (Routine)
14 April 1997Keystone Dam, USdaily low min-2.8 C (27.0 F)2.2 C (4.0 F)38 years19 of 100 (Routine)
13 April 1997Keystone Dam, USdaily low min-2.8 C (27.0 F)1.7 C (3.1 F)36 years17 of 100 (Routine)
12 April 1997Keystone Dam, USdaily low min-1.7 C (28.9 F)1.7 C (3.1 F)7 years9 of 100 (Routine)
9 April 1997Keystone Dam, USdaily rain29.2 mm (1.1 in)12.4 mm (0.5 in)30 years21 of 100 (Routine)
22 March 1997Keystone Dam, USdaily high max32.8 C (91.0 F)3.9 C (7.0 F)22 years15 of 100 (Routine)
7 February 1997Keystone Dam, USdaily rain7.4 mm (0.29 in)1.3 mm (0.05 in)18 years9 of 100 (Routine)
25 January 1997Keystone Dam, USdaily snowfall0.3 cm (0.1 in)0.3 cm (0.1 in)38 years15 of 100 (Routine)
24 January 1997Keystone Dam, USdaily snowfall0.3 cm (0.1 in)0.3 cm (0.1 in)38 years15 of 100 (Routine)
17 January 1997Keystone Dam, USdaily snowfall0.3 cm (0.1 in)0.3 cm (0.1 in)38 years15 of 100 (Routine)
15 January 1997Keystone Dam, USdaily snowfall3.3 cm (1.3 in)3.3 cm (1.3 in)38 years20 of 100 (Routine)
14 January 1997Keystone Dam, USdaily low max-7.8 C (18.0 F)2.2 C (4.0 F)33 years15 of 100 (Routine)
13 January 1997Keystone Dam, USdaily low max-9.4 C (15.1 F)5.5 C (9.9 F)22 years17 of 100 (Routine)
13 January 1997Keystone Dam, USdaily snowfall1.0 cm (0.4 in)1.0 cm (0.4 in)38 years17 of 100 (Routine)
12 January 1997Keystone Dam, USdaily low max (Tie)-8.3 C (17.1 F)tie34 years3 of 100 (Routine)
9 January 1997Keystone Dam, USdaily snowfall11.4 cm (4.5 in)6.3 cm (2.5 in)35 years26 of 100 (Routine)
4 January 1997Keystone Dam, USdaily high max23.9 C (75.0 F)4.5 C (8.1 F)35 years20 of 100 (Routine)
4 January 1997Keystone Dam, USdaily high min7.8 C (46.0 F)6.7 C (12.1 F)7 years17 of 100 (Routine)
3 January 1997Keystone Dam, USdaily high min11.1 C (52.0 F)5.0 C (9.0 F)33 years21 of 100 (Routine)
3 January 1997Keystone Dam, USmonthly high max26.1 C (79.0 F)0.5 C (0.9 F)15 years18 of 100 (Routine)

Climate Trend

17 complete years, 1966 to 1996
Annual mean temperature at Keystone Dam as warming stripes, 1966 to 1996 One stripe for each of 17 complete years at Keystone Dam, 1966 to 1996. Blue stripes are years cooler than the station's own mean of 14.8 C (58.6 F); red stripes are warmer. The coolest year was 1976, at 14.0 C (57.2 F), and the warmest was 1990, at 16.0 C (60.7 F). The strongest colour marks a difference of 1.2 C (2.2 F). 1966: 14.8 C, 0.0 C from the station mean1967: 14.8 C, 0.0 C from the station mean1969: 14.9 C, +0.1 C from the station mean1970: 14.8 C, 0.0 C from the station mean1971: 14.8 C, +0.1 C from the station mean1973: 14.9 C, +0.2 C from the station mean1974: 14.7 C, -0.1 C from the station mean1975: 14.3 C, -0.5 C from the station mean1976: 14.0 C, -0.7 C from the station mean1977: 15.2 C, +0.5 C from the station mean1980: 15.7 C, +1.0 C from the station mean1990: 16.0 C, +1.2 C from the station mean1992: 14.6 C, -0.2 C from the station mean1993: 14.0 C, -0.7 C from the station mean1994: 14.7 C, -0.1 C from the station mean1995: 14.7 C, 0.0 C from the station mean1996: 14.1 C, -0.7 C from the station mean1966197019751980198519901995
One stripe for each of 17 complete years at Keystone Dam, 1966 to 1996. Blue stripes are years cooler than the station's own mean of 14.8 C (58.6 F); red stripes are warmer. The coolest year was 1976, at 14.0 C (57.2 F), and the warmest was 1990, at 16.0 C (60.7 F). The strongest colour marks a difference of 1.2 C (2.2 F).
Annual mean temperature at Keystone Dam as warming stripes, 1966 to 1996
YearAnnual mean temperatureDifference from the station mean
196614.8 C+0.01 C
196714.8 C0.00 C
196914.9 C+0.12 C
197014.8 C+0.03 C
197114.8 C+0.06 C
197314.9 C+0.19 C
197414.7 C-0.09 C
197514.3 C-0.46 C
197614.0 C-0.74 C
197715.2 C+0.49 C
198015.7 C+0.97 C
199016.0 C+1.20 C
199214.6 C-0.20 C
199314.0 C-0.73 C
199414.7 C-0.06 C
199514.7 C-0.04 C
199614.1 C-0.69 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

1957 to 1997
Yearly extremes at Keystone Dam: the record and the median year
MeasureRecordYear of the recordMedian yearYears with a value
Hottest day (TXx)43.3 C (109.9 F)196439.4 C (102.9 F)41
Coldest night (TNn)-23.9 C (-11.0 F)1979-17.8 C (0.0 F)41
Wettest day (Rx1day)154.2 mm (6.1 in)198679.0 mm (3.1 in)41
Wettest five days (Rx5day)265.5 mm (10.5 in)1986115.8 mm (4.6 in)41
Longest dry spell (CDD)52 days196525 days41

Hottest day (TXx)

Hottest day (TXx) at Keystone Dam by year The hottest day of the year at Keystone Dam, 1957 to 1997. The record is 43.3 C (109.9 F) in 1964, marked on the chart; the median year is 39.4 C (102.9 F). 303540451960197019801990Record: 43.3 C (109.9 F) in 1964
The hottest day of the year at Keystone Dam, 1957 to 1997. The record is 43.3 C (109.9 F) in 1964, marked on the chart; the median year is 39.4 C (102.9 F).
Hottest day (TXx) at Keystone Dam by year
YearHottest day (TXx)
195739.4 C (102.9 F)
195838.3 C (100.9 F)
195936.7 C (98.1 F)
196038.3 C (100.9 F)
196136.7 C (98.1 F)
196240.6 C (105.1 F)
196340.0 C (104.0 F)
196443.3 C (109.9 F)
196540.6 C (105.1 F)
196640.6 C (105.1 F)
196737.8 C (100.0 F)
196838.9 C (102.0 F)
196940.6 C (105.1 F)
197042.2 C (108.0 F)
197140.0 C (104.0 F)
197239.4 C (102.9 F)
197336.7 C (98.1 F)
197442.8 C (109.0 F)
197537.8 C (100.0 F)
197638.9 C (102.0 F)
197741.7 C (107.1 F)
197840.6 C (105.1 F)
197936.1 C (97.0 F)
198042.2 C (108.0 F)
198141.7 C (107.1 F)
198240.6 C (105.1 F)
198341.1 C (106.0 F)
198441.7 C (107.1 F)
198540.6 C (105.1 F)
198643.3 C (109.9 F)
198738.9 C (102.0 F)
198838.3 C (100.9 F)
198937.2 C (99.0 F)
199040.0 C (104.0 F)
199138.9 C (102.0 F)
199235.0 C (95.0 F)
199339.4 C (102.9 F)
199436.7 C (98.1 F)
199538.3 C (100.9 F)
199642.2 C (108.0 F)
199732.8 C (91.0 F)

Coldest night (TNn)

Coldest night (TNn) at Keystone Dam by year The coldest night of the year at Keystone Dam, 1957 to 1997. The record is -23.9 C (-11.0 F) in 1979, marked on the chart; the median year is -17.8 C (0.0 F). -25-20-15-10-51960197019801990Record: -23.9 C (-11.0 F) in 1979
The coldest night of the year at Keystone Dam, 1957 to 1997. The record is -23.9 C (-11.0 F) in 1979, marked on the chart; the median year is -17.8 C (0.0 F).
Coldest night (TNn) at Keystone Dam by year
YearColdest night (TNn)
1957-5.0 C (23.0 F)
1958-11.1 C (12.0 F)
1959-22.2 C (-8.0 F)
1960-17.8 C (0.0 F)
1961-16.7 C (1.9 F)
1962-18.9 C (-2.0 F)
1963-19.4 C (-2.9 F)
1964-17.2 C (1.0 F)
1965-13.9 C (7.0 F)
1966-18.9 C (-2.0 F)
1967-14.4 C (6.1 F)
1968-18.9 C (-2.0 F)
1969-17.8 C (0.0 F)
1970-16.7 C (1.9 F)
1971-20.0 C (-4.0 F)
1972-17.8 C (0.0 F)
1973-18.3 C (-0.9 F)
1974-15.6 C (3.9 F)
1975-15.6 C (3.9 F)
1976-18.3 C (-0.9 F)
1977-21.7 C (-7.1 F)
1978-20.0 C (-4.0 F)
1979-23.9 C (-11.0 F)
1980-16.1 C (3.0 F)
1981-18.3 C (-0.9 F)
1982-19.4 C (-2.9 F)
1983-18.9 C (-2.0 F)
1984-21.1 C (-6.0 F)
1985-16.7 C (1.9 F)
1986-17.8 C (0.0 F)
1987-16.1 C (3.0 F)
1988-17.2 C (1.0 F)
1989-21.7 C (-7.1 F)
1990-17.8 C (0.0 F)
1991-14.4 C (6.1 F)
1992-10.0 C (14.0 F)
1993-15.0 C (5.0 F)
1994-14.4 C (6.1 F)
1995-12.8 C (9.0 F)
1996-23.3 C (-9.9 F)
1997-16.7 C (1.9 F)

Wettest day (Rx1day)

Wettest day (Rx1day) at Keystone Dam by year The wettest day of the year at Keystone Dam, 1957 to 1997. The record is 154.2 mm (6.1 in) in 1986, marked on the chart; the median year is 79.0 mm (3.1 in). 0501001502001960197019801990Record: 154.2 mm (6.1 in) in 1986
The wettest day of the year at Keystone Dam, 1957 to 1997. The record is 154.2 mm (6.1 in) in 1986, marked on the chart; the median year is 79.0 mm (3.1 in).
Wettest day (Rx1day) at Keystone Dam by year
YearWettest day (Rx1day)
195749.8 mm (2.0 in)
195854.9 mm (2.2 in)
1959127.0 mm (5.0 in)
1960130.8 mm (5.1 in)
196196.8 mm (3.8 in)
1962115.8 mm (4.6 in)
196366.0 mm (2.6 in)
196430.7 mm (1.2 in)
196561.0 mm (2.4 in)
196643.9 mm (1.7 in)
196758.4 mm (2.3 in)
196849.5 mm (1.9 in)
196996.8 mm (3.8 in)
197075.9 mm (3.0 in)
1971106.2 mm (4.2 in)
1972106.9 mm (4.2 in)
197379.0 mm (3.1 in)
1974104.1 mm (4.1 in)
197562.7 mm (2.5 in)
197644.5 mm (1.8 in)
197795.3 mm (3.8 in)
197852.1 mm (2.1 in)
197984.3 mm (3.3 in)
198095.3 mm (3.8 in)
198191.4 mm (3.6 in)
1982147.3 mm (5.8 in)
198392.7 mm (3.6 in)
198472.4 mm (2.9 in)
1985123.7 mm (4.9 in)
1986154.2 mm (6.1 in)
198755.4 mm (2.2 in)
198879.8 mm (3.1 in)
198975.9 mm (3.0 in)
199092.5 mm (3.6 in)
199168.1 mm (2.7 in)
199248.5 mm (1.9 in)
199366.0 mm (2.6 in)
199477.2 mm (3.0 in)
1995104.4 mm (4.1 in)
199679.2 mm (3.1 in)
199746.5 mm (1.8 in)

Wettest five days (Rx5day)

Wettest five days (Rx5day) at Keystone Dam by year The wettest five days of the year at Keystone Dam, 1957 to 1997. The record is 265.5 mm (10.5 in) in 1986, marked on the chart; the median year is 115.8 mm (4.6 in). 01002003001960197019801990Record: 265.5 mm (10.5 in) in 1986
The wettest five days of the year at Keystone Dam, 1957 to 1997. The record is 265.5 mm (10.5 in) in 1986, marked on the chart; the median year is 115.8 mm (4.6 in).
Wettest five days (Rx5day) at Keystone Dam by year
YearWettest five days (Rx5day)
1957118.2 mm (4.7 in)
195859.9 mm (2.4 in)
1959169.7 mm (6.7 in)
1960132.1 mm (5.2 in)
1961130.6 mm (5.1 in)
1962115.8 mm (4.6 in)
1963105.1 mm (4.1 in)
196492.1 mm (3.6 in)
1965111.3 mm (4.4 in)
196667.5 mm (2.7 in)
196793.7 mm (3.7 in)
196876.0 mm (3.0 in)
1969150.4 mm (5.9 in)
197081.8 mm (3.2 in)
1971196.4 mm (7.7 in)
1972115.8 mm (4.6 in)
197387.6 mm (3.4 in)
1974249.7 mm (9.8 in)
197578.0 mm (3.1 in)
197690.6 mm (3.6 in)
1977141.6 mm (5.6 in)
1978111.1 mm (4.4 in)
197992.0 mm (3.6 in)
1980207.1 mm (8.2 in)
1981105.4 mm (4.1 in)
1982162.5 mm (6.4 in)
1983198.5 mm (7.8 in)
1984119.0 mm (4.7 in)
1985154.9 mm (6.1 in)
1986265.5 mm (10.5 in)
1987125.0 mm (4.9 in)
1988142.3 mm (5.6 in)
198992.0 mm (3.6 in)
1990148.1 mm (5.8 in)
1991152.2 mm (6.0 in)
199280.9 mm (3.2 in)
1993114.7 mm (4.5 in)
1994111.0 mm (4.4 in)
1995174.2 mm (6.9 in)
1996106.1 mm (4.2 in)
199787.9 mm (3.5 in)

Longest dry spell (CDD)

Longest dry spell (CDD) at Keystone Dam by year The longest dry spell of the year at Keystone Dam, 1957 to 1997. The record is 52 days in 1965, marked on the chart; the median year is 25 days. 1020304050601960197019801990Record: 52 days in 1965
The longest dry spell of the year at Keystone Dam, 1957 to 1997. The record is 52 days in 1965, marked on the chart; the median year is 25 days.
Longest dry spell (CDD) at Keystone Dam by year
YearLongest dry spell (CDD)
195718 days
195828 days
195935 days
196023 days
196136 days
196223 days
196336 days
196417 days
196552 days
196629 days
196725 days
196815 days
196924 days
197031 days
197151 days
197231 days
197323 days
197421 days
197519 days
197635 days
197725 days
197821 days
197932 days
198031 days
198123 days
198220 days
198323 days
198423 days
198520 days
198636 days
198725 days
198829 days
198938 days
199023 days
199130 days
199220 days
199321 days
199433 days
199526 days
199641 days
199722 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.

Rainfall Return Levels

34 years, 1959 to 1996

A day with at least 79.5 mm (3.1 in) of rain is expected about once in 2 years. A day with at least 153.0 mm (6.0 in) of rain is expected about once in 100 years.

Rainfall return levels at Keystone Dam: the daily rain expected about once in a given number of years
Expected about once inA day with at leastNote
2 years79.5 mm (3.1 in)
5 years104.5 mm (4.1 in)
10 years118.6 mm (4.7 in)
25 years134.1 mm (5.3 in)
50 years144.1 mm (5.7 in)Longer than the 34 years of record
100 years153.0 mm (6.0 in)Longer than the 34 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, 34 years of values from 1959 to 1996.

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: 154.2 mm (6.1 in) in 1986; 127.0 mm (5.0 in) in 1959; 123.7 mm (4.9 in) in 1985.

Download the Data

  • Data for Keystone Dam standing records by year: CSV or JSON. Field meanings are on the data page.
  • Data for Keystone Dam 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 2026-10-13 (13 October 2026). Records are computed by this site and are not official.

Data as of . Last revised (2025-12-31).