Record envelope, standing records and threshold days for Rock Springs (USC00487840), Wyoming, United States, with 82 years of record.
Key Facts for Rock Springs
Rock Springs (USC00487840) is a weather station in Wyoming, United States at 41.58 latitude and -109.22 longitude, 1,943 m (6,375 ft) above sea level.
The station reports from 1898 to 1979, 82 years of record.
1,464 records set at Rock Springs still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Rock Springs set a daily record low maximum temperature of 5.0 C (41.0 F) on 9 May 1979.
About the Station
Location: Wyoming, United States, 41.58 latitude, -109.22 longitude.
Elevation: 1,943 m (6,375 ft).
Period of record: 1898 to 1979, 82 years.
Eligible elements: tmax, tmin, prcp, snow, snwd.
Daily Record Envelope and 2026
0 days at or beyond a record
Record highRecord low2026 daily maximum2026 daily minimum
The band shows the record high and record low for each calendar day at Rock Springs. 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 Rock Springs, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
15.0 C (59.0 F)
-38.3 C (-36.9 F)
n/a
n/a
Feb
21.1 C (70.0 F)
-31.7 C (-25.1 F)
n/a
n/a
Mar
22.8 C (73.0 F)
-23.9 C (-11.0 F)
n/a
n/a
Apr
26.7 C (80.1 F)
-20.6 C (-5.1 F)
n/a
n/a
May
43.3 C (109.9 F)
-8.3 C (17.1 F)
n/a
n/a
Jun
36.7 C (98.1 F)
-11.1 C (12.0 F)
n/a
n/a
Jul
36.7 C (98.1 F)
-2.2 C (28.0 F)
n/a
n/a
Aug
36.1 C (97.0 F)
-5.0 C (23.0 F)
n/a
n/a
Sep
34.4 C (93.9 F)
-17.2 C (1.0 F)
n/a
n/a
Oct
27.8 C (82.0 F)
-16.1 C (3.0 F)
n/a
n/a
Nov
21.1 C (70.0 F)
-29.4 C (-20.9 F)
n/a
n/a
Dec
15.0 C (59.0 F)
-36.1 C (-33.0 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Rock Springs still stand. 1899 holds the most, with 92.
Standing records at Rock Springs by the year they were set
Year set
Standing records
1898
3
1899
92
1901
18
1902
66
1933
45
1934
37
1935
23
1936
33
1937
26
1938
25
1939
42
1940
48
1941
25
1948
19
1949
57
1950
52
1951
25
1952
33
1953
41
1954
41
1955
31
1956
27
1957
25
1958
36
1959
25
1960
39
1961
18
1962
39
1963
33
1964
28
1965
32
1966
26
1967
25
1968
31
1969
41
1970
24
1971
31
1972
31
1973
34
1974
26
1975
19
1976
22
1977
33
1978
27
1979
10
All-Time Record Progression
1 new records
1 all-time records were set at Rock Springs between 5 May 1978 and 5 May 1978. Each dot is a new record.
When Rock Springs set new all-time records
Date
Kind
Detail
1978-05-05
Record daily snowfall
Record daily snowfall 35.6 cm (14.0 in)
Wettest Day of Each Month
Jun: 88.9 mm (3.5 in)
The wettest day on record for each calendar month at Rock Springs. The most was 88.9 mm (3.5 in) on 12 June 1899.
Record daily precipitation for each month at Rock Springs
Month
Record daily precipitation (mm)
Date
Jan
11.4 mm (0.4 in)
8 January 1962
Feb
17.8 mm (0.7 in)
7 February 1950
Mar
25.1 mm (1.0 in)
31 March 1957
Apr
19.3 mm (0.8 in)
28 April 1956
May
28.2 mm (1.1 in)
29 May 1967
Jun
88.9 mm (3.5 in)
12 June 1899
Jul
46.0 mm (1.8 in)
11 July 1937
Aug
37.1 mm (1.5 in)
30 August 1938
Sep
51.3 mm (2.0 in)
11 September 1973
Oct
24.9 mm (1.0 in)
13 October 1966
Nov
19.1 mm (0.8 in)
21 November 1937
Dec
21.3 mm (0.8 in)
12 December 1975
Period of Record Coverage
1898 to 1979
Complete yearUnder 90 percent of days
45 years of record at Rock Springs, 1898 to 1979. 6 years have data for under 90 percent of days and are left out of rankings: 1898, 1899, 1901, 1902, 1948, 1979.
Cooler than the station meanWarmer than the station mean
One stripe for each of 38 complete years at Rock Springs, 1933 to 1978. Blue stripes are years cooler than the station's own mean of 6.7 C (44.1 F); red stripes are warmer. The coolest year was 1973, at 5.2 C (41.3 F), and the warmest was 1954, at 8.1 C (46.5 F). The strongest colour marks a difference of 1.6 C (2.9 F).
Annual mean temperature at Rock Springs as warming stripes, 1933 to 1978
Year
Annual mean temperature
Difference from the station mean
1933
6.6 C
-0.11 C
1934
7.8 C
+1.10 C
1935
6.3 C
-0.38 C
1936
6.7 C
-0.02 C
1937
5.4 C
-1.33 C
1938
6.0 C
-0.67 C
1939
6.5 C
-0.21 C
1940
6.8 C
+0.04 C
1949
6.5 C
-0.23 C
1950
6.9 C
+0.14 C
1951
6.3 C
-0.42 C
1952
6.3 C
-0.37 C
1953
7.9 C
+1.19 C
1954
8.1 C
+1.35 C
1955
6.6 C
-0.12 C
1956
7.3 C
+0.59 C
1957
6.8 C
+0.04 C
1958
7.7 C
+1.00 C
1959
7.2 C
+0.53 C
1960
6.7 C
-0.01 C
1961
6.6 C
-0.07 C
1962
6.9 C
+0.22 C
1963
7.7 C
+1.01 C
1964
6.0 C
-0.76 C
1965
6.4 C
-0.27 C
1966
6.9 C
+0.17 C
1967
6.9 C
+0.20 C
1968
6.2 C
-0.54 C
1969
6.8 C
+0.10 C
1970
6.6 C
-0.09 C
1971
6.0 C
-0.73 C
1972
6.3 C
-0.45 C
1973
5.2 C
-1.56 C
1974
6.7 C
+0.00 C
1975
6.0 C
-0.71 C
1976
7.0 C
+0.30 C
1977
7.8 C
+1.08 C
1978
6.6 C
-0.13 C
The fitted trend in annual mean temperature here over 1933 to 1978 is -0.01 C (-0.17 to 0.15) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: -0.02 F (-0.31 to 0.28) per decade. The slope is a straight line fitted to 38 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Rock Springs
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
-0.01 C (-0.17 to 0.15) per decade
-0.02 F (-0.31 to 0.28) per decade
1933 to 1978
38
Not clearly different from zero
Mean daily maximum
-0.1 C (-0.3 to 0.1) per decade
-0.2 F (-0.6 to 0.2) per decade
1933 to 1978
38
Not clearly different from zero
Mean daily minimum
0.1 C (-0.1 to 0.3) per decade
0.2 F (-0.1 to 0.5) per decade
1933 to 1978
38
Not 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
1898 to 1979
Yearly extremes at Rock Springs: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
43.3 C (109.9 F)
1902
34.4 C (93.9 F)
45
Coldest night (TNn)
-38.3 C (-36.9 F)
1963
-27.8 C (-18.0 F)
45
Wettest day (Rx1day)
88.9 mm (3.5 in)
1899
18.8 mm (0.7 in)
45
Wettest five days (Rx5day)
139.7 mm (5.5 in)
1899
28.7 mm (1.1 in)
45
Longest dry spell (CDD)
83 days
1939
35 days
45
Hottest day (TXx)
The hottest day of the year at Rock Springs, 1898 to 1979. The record is 43.3 C (109.9 F) in 1902, marked on the chart; the median year is 34.4 C (93.9 F).
Hottest day (TXx) at Rock Springs by year
Year
Hottest day (TXx)
1898
13.9 C (57.0 F)
1899
33.9 C (93.0 F)
1901
30.6 C (87.1 F)
1902
43.3 C (109.9 F)
1933
35.0 C (95.0 F)
1934
35.0 C (95.0 F)
1935
36.7 C (98.1 F)
1936
35.0 C (95.0 F)
1937
34.4 C (93.9 F)
1938
34.4 C (93.9 F)
1939
36.1 C (97.0 F)
1940
36.1 C (97.0 F)
1941
33.9 C (93.0 F)
1948
34.4 C (93.9 F)
1949
35.0 C (95.0 F)
1950
34.4 C (93.9 F)
1951
35.0 C (95.0 F)
1952
33.9 C (93.0 F)
1953
35.0 C (95.0 F)
1954
36.7 C (98.1 F)
1955
35.0 C (95.0 F)
1956
33.9 C (93.0 F)
1957
33.9 C (93.0 F)
1958
36.1 C (97.0 F)
1959
35.6 C (96.1 F)
1960
35.6 C (96.1 F)
1961
33.9 C (93.0 F)
1962
34.4 C (93.9 F)
1963
34.4 C (93.9 F)
1964
35.0 C (95.0 F)
1965
32.8 C (91.0 F)
1966
35.0 C (95.0 F)
1967
33.3 C (91.9 F)
1968
32.8 C (91.0 F)
1969
34.4 C (93.9 F)
1970
34.4 C (93.9 F)
1971
34.4 C (93.9 F)
1972
34.4 C (93.9 F)
1973
35.0 C (95.0 F)
1974
35.0 C (95.0 F)
1975
35.0 C (95.0 F)
1976
35.6 C (96.1 F)
1977
34.4 C (93.9 F)
1978
35.6 C (96.1 F)
1979
26.7 C (80.1 F)
Coldest night (TNn)
The coldest night of the year at Rock Springs, 1898 to 1979. The record is -38.3 C (-36.9 F) in 1963, marked on the chart; the median year is -27.8 C (-18.0 F).
Coldest night (TNn) at Rock Springs by year
Year
Coldest night (TNn)
1898
-27.8 C (-18.0 F)
1899
-34.4 C (-29.9 F)
1901
-21.1 C (-6.0 F)
1902
-21.1 C (-6.0 F)
1933
-31.7 C (-25.1 F)
1934
-20.6 C (-5.1 F)
1935
-24.4 C (-11.9 F)
1936
-28.9 C (-20.0 F)
1937
-31.1 C (-24.0 F)
1938
-23.3 C (-9.9 F)
1939
-28.3 C (-18.9 F)
1940
-33.9 C (-29.0 F)
1941
-30.6 C (-23.1 F)
1948
-27.2 C (-17.0 F)
1949
-33.9 C (-29.0 F)
1950
-26.1 C (-15.0 F)
1951
-28.9 C (-20.0 F)
1952
-27.8 C (-18.0 F)
1953
-22.2 C (-8.0 F)
1954
-24.4 C (-11.9 F)
1955
-26.7 C (-16.1 F)
1956
-31.1 C (-24.0 F)
1957
-28.9 C (-20.0 F)
1958
-26.1 C (-15.0 F)
1959
-25.6 C (-14.1 F)
1960
-33.9 C (-29.0 F)
1961
-28.3 C (-18.9 F)
1962
-33.9 C (-29.0 F)
1963
-38.3 C (-36.9 F)
1964
-28.3 C (-18.9 F)
1965
-23.3 C (-9.9 F)
1966
-22.2 C (-8.0 F)
1967
-22.2 C (-8.0 F)
1968
-25.0 C (-13.0 F)
1969
-23.9 C (-11.0 F)
1970
-27.2 C (-17.0 F)
1971
-25.0 C (-13.0 F)
1972
-36.1 C (-33.0 F)
1973
-33.9 C (-29.0 F)
1974
-32.8 C (-27.0 F)
1975
-25.0 C (-13.0 F)
1976
-25.6 C (-14.1 F)
1977
-25.0 C (-13.0 F)
1978
-35.0 C (-31.0 F)
1979
-35.6 C (-32.1 F)
Wettest day (Rx1day)
The wettest day of the year at Rock Springs, 1898 to 1979. The record is 88.9 mm (3.5 in) in 1899, marked on the chart; the median year is 18.8 mm (0.7 in).
Wettest day (Rx1day) at Rock Springs by year
Year
Wettest day (Rx1day)
1898
5.1 mm (0.20 in)
1899
88.9 mm (3.5 in)
1901
5.1 mm (0.20 in)
1902
19.6 mm (0.8 in)
1933
11.2 mm (0.4 in)
1934
15.0 mm (0.6 in)
1935
12.7 mm (0.5 in)
1936
34.3 mm (1.4 in)
1937
46.0 mm (1.8 in)
1938
37.1 mm (1.5 in)
1939
16.0 mm (0.6 in)
1940
18.5 mm (0.7 in)
1941
13.5 mm (0.5 in)
1948
13.5 mm (0.5 in)
1949
27.2 mm (1.1 in)
1950
17.8 mm (0.7 in)
1951
17.5 mm (0.7 in)
1952
18.0 mm (0.7 in)
1953
13.5 mm (0.5 in)
1954
8.6 mm (0.34 in)
1955
15.2 mm (0.6 in)
1956
26.4 mm (1.0 in)
1957
25.1 mm (1.0 in)
1958
18.8 mm (0.7 in)
1959
14.5 mm (0.6 in)
1960
13.2 mm (0.5 in)
1961
13.7 mm (0.5 in)
1962
23.4 mm (0.9 in)
1963
21.3 mm (0.8 in)
1964
19.8 mm (0.8 in)
1965
52.3 mm (2.1 in)
1966
34.3 mm (1.4 in)
1967
28.2 mm (1.1 in)
1968
19.8 mm (0.8 in)
1969
37.3 mm (1.5 in)
1970
51.6 mm (2.0 in)
1971
25.7 mm (1.0 in)
1972
17.3 mm (0.7 in)
1973
51.3 mm (2.0 in)
1974
12.4 mm (0.5 in)
1975
25.4 mm (1.0 in)
1976
16.5 mm (0.6 in)
1977
27.4 mm (1.1 in)
1978
31.5 mm (1.2 in)
1979
16.5 mm (0.6 in)
Wettest five days (Rx5day)
The wettest five days of the year at Rock Springs, 1898 to 1979. The record is 139.7 mm (5.5 in) in 1899, marked on the chart; the median year is 28.7 mm (1.1 in).
Wettest five days (Rx5day) at Rock Springs by year
Year
Wettest five days (Rx5day)
1898
5.6 mm (0.22 in)
1899
139.7 mm (5.5 in)
1901
9.2 mm (0.36 in)
1902
36.9 mm (1.5 in)
1933
19.1 mm (0.8 in)
1934
24.5 mm (1.0 in)
1935
28.0 mm (1.1 in)
1936
43.5 mm (1.7 in)
1937
86.6 mm (3.4 in)
1938
57.7 mm (2.3 in)
1939
16.3 mm (0.6 in)
1940
36.2 mm (1.4 in)
1941
24.1 mm (0.9 in)
1948
13.5 mm (0.5 in)
1949
47.8 mm (1.9 in)
1950
35.1 mm (1.4 in)
1951
24.1 mm (0.9 in)
1952
28.2 mm (1.1 in)
1953
16.3 mm (0.6 in)
1954
9.9 mm (0.39 in)
1955
18.3 mm (0.7 in)
1956
56.3 mm (2.2 in)
1957
33.9 mm (1.3 in)
1958
20.4 mm (0.8 in)
1959
28.7 mm (1.1 in)
1960
23.6 mm (0.9 in)
1961
24.1 mm (0.9 in)
1962
27.0 mm (1.1 in)
1963
25.4 mm (1.0 in)
1964
24.5 mm (1.0 in)
1965
66.8 mm (2.6 in)
1966
43.4 mm (1.7 in)
1967
30.5 mm (1.2 in)
1968
30.0 mm (1.2 in)
1969
41.4 mm (1.6 in)
1970
73.5 mm (2.9 in)
1971
39.1 mm (1.5 in)
1972
28.7 mm (1.1 in)
1973
53.6 mm (2.1 in)
1974
27.2 mm (1.1 in)
1975
39.7 mm (1.6 in)
1976
28.4 mm (1.1 in)
1977
36.3 mm (1.4 in)
1978
39.4 mm (1.6 in)
1979
17.8 mm (0.7 in)
Longest dry spell (CDD)
The longest dry spell of the year at Rock Springs, 1898 to 1979. The record is 83 days in 1939, marked on the chart; the median year is 35 days.
Longest dry spell (CDD) at Rock Springs by year
Year
Longest dry spell (CDD)
1898
22 days
1899
35 days
1901
34 days
1902
38 days
1933
39 days
1934
35 days
1935
31 days
1936
44 days
1937
20 days
1938
28 days
1939
83 days
1940
40 days
1941
21 days
1948
27 days
1949
38 days
1950
41 days
1951
43 days
1952
69 days
1953
43 days
1954
34 days
1955
37 days
1956
41 days
1957
23 days
1958
59 days
1959
51 days
1960
75 days
1961
33 days
1962
50 days
1963
30 days
1964
24 days
1965
27 days
1966
30 days
1967
22 days
1968
26 days
1969
52 days
1970
27 days
1971
36 days
1972
27 days
1973
27 days
1974
52 days
1975
26 days
1976
31 days
1977
46 days
1978
40 days
1979
24 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
38 years with a frost
Across 38 years with a frost, the median last spring frost at Rock Springs falls on 27 May and the median first autumn frost on 14 September, which leaves a median of 111 days between them.
Fitted over all years, the growing season changes by -0.2 days per decade at this station.
Frost dates and growing season at Rock Springs
Measure
Median, all years
Earliest period
Recent period (1949 to 1978)
Recent against earliest
Fitted trend
Last spring frost
27 May
n/a
26 May
n/a
+0.5 days per decade
First autumn frost
14 September
n/a
14 September
n/a
+0.2 days per decade
Growing days
111 days
n/a
112 days
n/a
-0.2 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
39 years, 1933 to 1978
A day with at least 20.8 mm (0.8 in) of rain is expected about once in 2 years. A day with at least 71.0 mm (2.8 in) of rain is expected about once in 100 years.
Rainfall return levels at Rock Springs: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
20.8 mm (0.8 in)
5 years
30.9 mm (1.2 in)
10 years
38.8 mm (1.5 in)
25 years
50.2 mm (2.0 in)
50 years
60.0 mm (2.4 in)
Longer than the 39 years of record
100 years
71.0 mm (2.8 in)
Longer than the 39 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, 39 years of values from 1933 to 1978.
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: 52.3 mm (2.1 in) in 1965; 51.6 mm (2.0 in) in 1970; 51.3 mm (2.0 in) in 1973.
Download the Data
Data for Rock Springs standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Rock Springs 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.