Record envelope, standing records and threshold days for Folsom Dam (USC00043113), California, United States, with 39 years of record.
Key Facts for Folsom Dam
Folsom Dam (USC00043113) is a weather station in California, United States at 38.70 latitude and -121.17 longitude, 107 m (350 ft) above sea level.
The station reports from 1955 to 1993, 39 years of record.
1,464 records set at Folsom Dam still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Folsom Dam set a daily record precipitation of 34.8 mm (1.4 in) on 24 March 1993.
About the Station
Location: California, United States, 38.70 latitude, -121.17 longitude.
Elevation: 107 m (350 ft).
Period of record: 1955 to 1993, 39 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 Folsom 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 Folsom Dam, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
22.8 C (73.0 F)
-8.3 C (17.1 F)
n/a
n/a
Feb
25.6 C (78.1 F)
-7.2 C (19.0 F)
n/a
n/a
Mar
30.0 C (86.0 F)
-3.3 C (26.1 F)
n/a
n/a
Apr
34.4 C (93.9 F)
-1.1 C (30.0 F)
n/a
n/a
May
41.1 C (106.0 F)
1.7 C (35.1 F)
n/a
n/a
Jun
44.4 C (111.9 F)
6.1 C (43.0 F)
n/a
n/a
Jul
46.1 C (115.0 F)
10.0 C (50.0 F)
n/a
n/a
Aug
45.6 C (114.1 F)
7.2 C (45.0 F)
n/a
n/a
Sep
42.2 C (108.0 F)
7.8 C (46.0 F)
n/a
n/a
Oct
38.9 C (102.0 F)
0.0 C (32.0 F)
n/a
n/a
Nov
30.0 C (86.0 F)
-3.3 C (26.1 F)
n/a
n/a
Dec
23.3 C (73.9 F)
-8.9 C (16.0 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Folsom Dam still stand. 1971 holds the most, with 63.
Standing records at Folsom Dam by the year they were set
Year set
Standing records
1955
19
1956
38
1957
37
1958
40
1959
48
1960
51
1961
45
1962
61
1963
56
1964
48
1965
39
1966
50
1967
52
1968
28
1969
27
1970
36
1971
63
1972
61
1973
42
1974
30
1975
55
1976
36
1977
34
1978
29
1979
16
1980
30
1981
30
1982
25
1983
19
1984
27
1985
48
1986
31
1987
51
1988
35
1989
32
1990
34
1991
29
1992
21
1993
11
Wettest Day of Each Month
Oct: 105.7 mm (4.2 in)
The wettest day on record for each calendar month at Folsom Dam. The most was 105.7 mm (4.2 in) on 13 October 1962.
Record daily precipitation for each month at Folsom Dam
Month
Record daily precipitation (mm)
Date
Jan
78.7 mm (3.1 in)
5 January 1982
Feb
76.2 mm (3.0 in)
19 February 1986
Mar
76.5 mm (3.0 in)
13 March 1983
Apr
66.3 mm (2.6 in)
20 April 1988
May
46.2 mm (1.8 in)
28 May 1990
Jun
20.6 mm (0.8 in)
12 June 1958
Jul
41.1 mm (1.6 in)
9 July 1974
Aug
22.4 mm (0.9 in)
15 August 1976
Sep
38.1 mm (1.5 in)
17 September 1989
Oct
105.7 mm (4.2 in)
13 October 1962
Nov
68.6 mm (2.7 in)
25 November 1985
Dec
58.9 mm (2.3 in)
25 December 1983
Period of Record Coverage
1955 to 1993
Complete yearUnder 90 percent of days
39 years of record at Folsom Dam, 1955 to 1993. 4 years have data for under 90 percent of days and are left out of rankings: 1955, 1986, 1987, 1993.
Cooler than the station meanWarmer than the station mean
One stripe for each of 34 complete years at Folsom Dam, 1956 to 1992. Blue stripes are years cooler than the station's own mean of 16.5 C (61.6 F); red stripes are warmer. The coolest year was 1975, at 15.2 C (59.3 F), and the warmest was 1958, at 17.6 C (63.6 F). The strongest colour marks a difference of 1.3 C (2.3 F).
Annual mean temperature at Folsom Dam as warming stripes, 1956 to 1992
Year
Annual mean temperature
Difference from the station mean
1956
16.6 C
+0.12 C
1957
16.7 C
+0.19 C
1958
17.6 C
+1.09 C
1959
17.5 C
+0.99 C
1960
16.8 C
+0.33 C
1961
16.4 C
-0.07 C
1962
15.9 C
-0.61 C
1963
15.5 C
-1.00 C
1964
15.7 C
-0.78 C
1965
15.7 C
-0.76 C
1966
16.6 C
+0.17 C
1967
16.4 C
-0.11 C
1968
16.4 C
-0.09 C
1969
16.4 C
-0.10 C
1970
16.5 C
+0.02 C
1971
15.3 C
-1.21 C
1972
15.7 C
-0.76 C
1973
16.2 C
-0.26 C
1974
16.3 C
-0.13 C
1975
15.2 C
-1.29 C
1976
16.5 C
+0.08 C
1977
16.7 C
+0.21 C
1978
16.8 C
+0.38 C
1979
16.7 C
+0.21 C
1980
16.6 C
+0.15 C
1981
17.2 C
+0.72 C
1982
15.8 C
-0.65 C
1984
17.0 C
+0.57 C
1985
16.0 C
-0.49 C
1988
17.5 C
+1.04 C
1989
16.5 C
+0.02 C
1990
16.9 C
+0.48 C
1991
17.0 C
+0.50 C
1992
17.5 C
+1.03 C
The fitted trend in annual mean temperature here over 1956 to 1992 is 0.1 C (-0.1 to 0.3) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.2 F (-0.1 to 0.6) per decade. The slope is a straight line fitted to 34 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Folsom Dam
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.1 C (-0.1 to 0.3) per decade
0.2 F (-0.1 to 0.6) per decade
1956 to 1992
34
Not clearly different from zero
Mean daily maximum
0.1 C (-0.1 to 0.4) per decade
0.2 F (-0.2 to 0.7) per decade
1956 to 1992
34
Not clearly different from zero
Mean daily minimum
0.1 C (-0.1 to 0.3) per decade
0.2 F (-0.1 to 0.6) per decade
1956 to 1992
34
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
1955 to 1993
Yearly extremes at Folsom Dam: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
46.1 C (115.0 F)
1972
41.7 C (107.1 F)
39
Coldest night (TNn)
-8.9 C (16.0 F)
1972
-3.3 C (26.1 F)
39
Wettest day (Rx1day)
105.7 mm (4.2 in)
1962
46.2 mm (1.8 in)
39
Wettest five days (Rx5day)
248.2 mm (9.8 in)
1962
86.9 mm (3.4 in)
39
Longest dry spell (CDD)
179 days
1966
101 days
39
Hottest day (TXx)
The hottest day of the year at Folsom Dam, 1955 to 1993. The record is 46.1 C (115.0 F) in 1972, marked on the chart; the median year is 41.7 C (107.1 F).
Hottest day (TXx) at Folsom Dam by year
Year
Hottest day (TXx)
1955
28.9 C (84.0 F)
1956
42.2 C (108.0 F)
1957
41.7 C (107.1 F)
1958
41.1 C (106.0 F)
1959
42.8 C (109.0 F)
1960
42.8 C (109.0 F)
1961
44.4 C (111.9 F)
1962
40.0 C (104.0 F)
1963
40.0 C (104.0 F)
1964
40.6 C (105.1 F)
1965
38.3 C (100.9 F)
1966
41.7 C (107.1 F)
1967
42.8 C (109.0 F)
1968
40.6 C (105.1 F)
1969
42.2 C (108.0 F)
1970
41.1 C (106.0 F)
1971
42.2 C (108.0 F)
1972
46.1 C (115.0 F)
1973
41.7 C (107.1 F)
1974
40.6 C (105.1 F)
1975
42.8 C (109.0 F)
1976
41.1 C (106.0 F)
1977
42.2 C (108.0 F)
1978
45.6 C (114.1 F)
1979
40.6 C (105.1 F)
1980
42.8 C (109.0 F)
1981
41.7 C (107.1 F)
1982
40.0 C (104.0 F)
1983
41.1 C (106.0 F)
1984
42.2 C (108.0 F)
1985
41.7 C (107.1 F)
1986
39.4 C (102.9 F)
1987
40.0 C (104.0 F)
1988
43.9 C (111.0 F)
1989
43.3 C (109.9 F)
1990
42.8 C (109.0 F)
1991
43.9 C (111.0 F)
1992
41.7 C (107.1 F)
1993
29.4 C (84.9 F)
Coldest night (TNn)
The coldest night of the year at Folsom Dam, 1955 to 1993. The record is -8.9 C (16.0 F) in 1972, marked on the chart; the median year is -3.3 C (26.1 F).
Coldest night (TNn) at Folsom Dam by year
Year
Coldest night (TNn)
1955
-1.7 C (28.9 F)
1956
-3.9 C (25.0 F)
1957
-3.3 C (26.1 F)
1958
-2.2 C (28.0 F)
1959
-3.3 C (26.1 F)
1960
-5.0 C (23.0 F)
1961
-4.4 C (24.1 F)
1962
-8.3 C (17.1 F)
1963
-6.1 C (21.0 F)
1964
-1.7 C (28.9 F)
1965
-2.8 C (27.0 F)
1966
-3.3 C (26.1 F)
1967
-3.9 C (25.0 F)
1968
-3.9 C (25.0 F)
1969
-2.8 C (27.0 F)
1970
-3.9 C (25.0 F)
1971
-3.3 C (26.1 F)
1972
-8.9 C (16.0 F)
1973
-6.1 C (21.0 F)
1974
-2.8 C (27.0 F)
1975
-3.9 C (25.0 F)
1976
-2.8 C (27.0 F)
1977
-1.1 C (30.0 F)
1978
-2.2 C (28.0 F)
1979
-1.7 C (28.9 F)
1980
-0.6 C (30.9 F)
1981
1.1 C (34.0 F)
1982
-0.6 C (30.9 F)
1983
-1.1 C (30.0 F)
1984
0.0 C (32.0 F)
1985
-3.9 C (25.0 F)
1986
-0.6 C (30.9 F)
1987
-1.1 C (30.0 F)
1988
-3.3 C (26.1 F)
1989
-7.2 C (19.0 F)
1990
-6.7 C (19.9 F)
1991
-0.6 C (30.9 F)
1992
-0.6 C (30.9 F)
1993
-3.9 C (25.0 F)
Wettest day (Rx1day)
The wettest day of the year at Folsom Dam, 1955 to 1993. The record is 105.7 mm (4.2 in) in 1962, marked on the chart; the median year is 46.2 mm (1.8 in).
Wettest day (Rx1day) at Folsom Dam by year
Year
Wettest day (Rx1day)
1955
41.7 mm (1.6 in)
1956
41.7 mm (1.6 in)
1957
37.3 mm (1.5 in)
1958
55.6 mm (2.2 in)
1959
50.8 mm (2.0 in)
1960
50.3 mm (2.0 in)
1961
37.6 mm (1.5 in)
1962
105.7 mm (4.2 in)
1963
55.1 mm (2.2 in)
1964
59.2 mm (2.3 in)
1965
35.1 mm (1.4 in)
1966
49.0 mm (1.9 in)
1967
67.1 mm (2.6 in)
1968
45.7 mm (1.8 in)
1969
49.5 mm (1.9 in)
1970
45.2 mm (1.8 in)
1971
40.9 mm (1.6 in)
1972
36.6 mm (1.4 in)
1973
47.8 mm (1.9 in)
1974
41.1 mm (1.6 in)
1975
37.1 mm (1.5 in)
1976
36.8 mm (1.4 in)
1977
31.2 mm (1.2 in)
1978
62.7 mm (2.5 in)
1979
43.4 mm (1.7 in)
1980
38.6 mm (1.5 in)
1981
63.5 mm (2.5 in)
1982
78.7 mm (3.1 in)
1983
76.5 mm (3.0 in)
1984
32.3 mm (1.3 in)
1985
68.6 mm (2.7 in)
1986
76.2 mm (3.0 in)
1987
58.9 mm (2.3 in)
1988
66.3 mm (2.6 in)
1989
38.1 mm (1.5 in)
1990
46.2 mm (1.8 in)
1991
53.6 mm (2.1 in)
1992
41.9 mm (1.6 in)
1993
38.4 mm (1.5 in)
Wettest five days (Rx5day)
The wettest five days of the year at Folsom Dam, 1955 to 1993. The record is 248.2 mm (9.8 in) in 1962, marked on the chart; the median year is 86.9 mm (3.4 in).
Wettest five days (Rx5day) at Folsom Dam by year
Year
Wettest five days (Rx5day)
1955
151.4 mm (6.0 in)
1956
70.1 mm (2.8 in)
1957
72.3 mm (2.8 in)
1958
144.6 mm (5.7 in)
1959
74.7 mm (2.9 in)
1960
78.3 mm (3.1 in)
1961
71.3 mm (2.8 in)
1962
248.2 mm (9.8 in)
1963
104.9 mm (4.1 in)
1964
142.0 mm (5.6 in)
1965
70.1 mm (2.8 in)
1966
83.1 mm (3.3 in)
1967
132.4 mm (5.2 in)
1968
65.7 mm (2.6 in)
1969
152.4 mm (6.0 in)
1970
128.5 mm (5.1 in)
1971
86.9 mm (3.4 in)
1972
72.4 mm (2.9 in)
1973
122.3 mm (4.8 in)
1974
57.9 mm (2.3 in)
1975
70.6 mm (2.8 in)
1976
39.8 mm (1.6 in)
1977
60.1 mm (2.4 in)
1978
138.6 mm (5.5 in)
1979
83.9 mm (3.3 in)
1980
119.9 mm (4.7 in)
1981
134.1 mm (5.3 in)
1982
116.9 mm (4.6 in)
1983
105.4 mm (4.1 in)
1984
55.2 mm (2.2 in)
1985
110.8 mm (4.4 in)
1986
228.1 mm (9.0 in)
1987
74.9 mm (2.9 in)
1988
90.7 mm (3.6 in)
1989
73.8 mm (2.9 in)
1990
67.3 mm (2.6 in)
1991
126.4 mm (5.0 in)
1992
116.1 mm (4.6 in)
1993
72.0 mm (2.8 in)
Longest dry spell (CDD)
The longest dry spell of the year at Folsom Dam, 1955 to 1993. The record is 179 days in 1966, marked on the chart; the median year is 101 days.
Longest dry spell (CDD) at Folsom Dam by year
Year
Longest dry spell (CDD)
1955
18 days
1956
111 days
1957
129 days
1958
101 days
1959
117 days
1960
162 days
1961
127 days
1962
84 days
1963
124 days
1964
82 days
1965
112 days
1966
179 days
1967
92 days
1968
72 days
1969
119 days
1970
128 days
1971
91 days
1972
86 days
1973
111 days
1974
109 days
1975
54 days
1976
123 days
1977
108 days
1978
69 days
1979
78 days
1980
100 days
1981
121 days
1982
77 days
1983
105 days
1984
72 days
1985
98 days
1986
61 days
1987
91 days
1988
128 days
1989
59 days
1990
140 days
1991
71 days
1992
112 days
1993
14 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
30 years with a frost
Across 30 years with a frost, the median last spring frost at Folsom Dam falls on 5 February and the median first autumn frost on 8 December, which leaves a median of 304 days between them.
Fitted over all years, the growing season changes by +7.9 days per decade at this station.
Frost dates and growing season at Folsom Dam
Measure
Median, all years
Earliest period
Recent period (1956 to 1992)
Recent against earliest
Fitted trend
Last spring frost
5 February
n/a
5 February
n/a
-7.4 days per decade
First autumn frost
8 December
n/a
8 December
n/a
+0.4 days per decade
Growing days
304 days
n/a
304 days
n/a
+7.9 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.
Rainfall Return Levels
35 years, 1956 to 1992
A day with at least 46.5 mm (1.8 in) of rain is expected about once in 2 years. A day with at least 112.2 mm (4.4 in) of rain is expected about once in 100 years.
Rainfall return levels at Folsom Dam: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
46.5 mm (1.8 in)
5 years
59.9 mm (2.4 in)
10 years
70.2 mm (2.8 in)
25 years
85.2 mm (3.4 in)
50 years
98.0 mm (3.9 in)
Longer than the 35 years of record
100 years
112.2 mm (4.4 in)
Longer than the 35 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, 35 years of values from 1956 to 1992.
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: 105.7 mm (4.2 in) in 1962; 78.7 mm (3.1 in) in 1982; 76.5 mm (3.0 in) in 1983.
Download the Data
Data for Folsom Dam standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Folsom 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 2026-10-14 (14 October 2026). Records are computed by this site and are not official.