Record envelope, standing records and threshold days for Aspen (USC00050370), Colorado, United States, with 81 years of record.
Key Facts for Aspen
Aspen (USC00050370) is a weather station in Colorado, United States at 39.18 latitude and -106.83 longitude, 2,417 m (7,928 ft) above sea level.
The station reports from 1899 to 1979, 81 years of record.
1,464 records set at Aspen still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Aspen set a daily record low minimum temperature of -22.8 C (-9.0 F) on 30 November 1979.
About the Station
Location: Colorado, United States, 39.18 latitude, -106.83 longitude.
Elevation: 2,417 m (7,928 ft).
Period of record: 1899 to 1979, 81 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 Aspen. 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 Aspen, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
14.4 C (57.9 F)
-38.3 C (-36.9 F)
n/a
n/a
Feb
15.6 C (60.1 F)
-34.4 C (-29.9 F)
n/a
n/a
Mar
21.1 C (70.0 F)
-32.2 C (-26.0 F)
n/a
n/a
Apr
26.1 C (79.0 F)
-23.3 C (-9.9 F)
n/a
n/a
May
29.4 C (84.9 F)
-10.0 C (14.0 F)
n/a
n/a
Jun
33.9 C (93.0 F)
-9.4 C (15.1 F)
n/a
n/a
Jul
34.4 C (93.9 F)
-0.6 C (30.9 F)
n/a
n/a
Aug
33.3 C (91.9 F)
-2.8 C (27.0 F)
n/a
n/a
Sep
31.7 C (89.1 F)
-9.4 C (15.1 F)
n/a
n/a
Oct
29.4 C (84.9 F)
-16.1 C (3.0 F)
n/a
n/a
Nov
20.6 C (69.1 F)
-28.3 C (-18.9 F)
n/a
n/a
Dec
16.7 C (62.1 F)
-29.4 C (-20.9 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Aspen still stand. 1959 holds the most, with 51.
Standing records at Aspen by the year they were set
Year set
Standing records
1914
43
1915
27
1916
33
1917
29
1918
34
1919
10
1934
23
1935
25
1936
31
1937
29
1938
24
1939
38
1940
32
1941
23
1942
47
1943
50
1944
23
1945
21
1946
38
1947
32
1948
26
1949
21
1950
39
1951
21
1952
18
1953
32
1954
31
1955
28
1956
29
1957
28
1958
16
1959
51
1960
21
1961
18
1962
38
1963
26
1964
37
1965
22
1966
23
1967
26
1968
22
1969
30
1970
23
1971
32
1972
24
1973
20
1974
14
1975
25
1976
13
1977
32
1978
33
1979
33
All-Time Record Progression
4 new records
4 all-time records were set at Aspen between 12 January 1963 and 7 August 1975. Each dot is a new record.
When Aspen set new all-time records
Date
Kind
Detail
1963-01-12
Record low maximum temperature
Record low maximum temperature -20.6 C (-5.1 F)
1965-03-24
Record daily snowfall
Record daily snowfall 63.5 cm (25.0 in)
1966-12-06
Record daily precipitation
Record daily precipitation 52.3 mm (2.1 in)
1975-08-07
Record high minimum temperature
Record high minimum temperature 15.6 C (60.1 F)
Wettest Day of Each Month
Dec: 52.3 mm (2.1 in)
The wettest day on record for each calendar month at Aspen. The most was 52.3 mm (2.1 in) on 6 December 1966.
Record daily precipitation for each month at Aspen
Month
Record daily precipitation (mm)
Date
Jan
38.1 mm (1.5 in)
14 January 1935
Feb
40.6 mm (1.6 in)
3 February 1936
Mar
43.9 mm (1.7 in)
24 March 1965
Apr
31.0 mm (1.2 in)
7 April 1957
May
34.5 mm (1.4 in)
9 May 1957
Jun
46.0 mm (1.8 in)
2 June 1943
Jul
50.8 mm (2.0 in)
18 July 1935
Aug
32.8 mm (1.3 in)
5 August 1964
Sep
35.1 mm (1.4 in)
9 September 1941
Oct
28.7 mm (1.1 in)
31 October 1963
Nov
40.6 mm (1.6 in)
2 November 1934
Dec
52.3 mm (2.1 in)
6 December 1966
Period of Record Coverage
1914 to 1979
Complete yearUnder 90 percent of days
52 years of record at Aspen, 1914 to 1979. 7 years have data for under 90 percent of days and are left out of rankings: 1917, 1919, 1934, 1942, 1948, 1978, 1979.
Cooler than the station meanWarmer than the station mean
One stripe for each of 41 complete years at Aspen, 1914 to 1976. Blue stripes are years cooler than the station's own mean of 4.8 C (40.6 F); red stripes are warmer. The coolest year was 1955, at 3.8 C (38.9 F), and the warmest was 1954, at 6.0 C (42.9 F). The strongest colour marks a difference of 1.3 C (2.3 F).
Annual mean temperature at Aspen as warming stripes, 1914 to 1976
Year
Annual mean temperature
Difference from the station mean
1914
5.3 C
+0.53 C
1915
4.8 C
+0.04 C
1916
4.7 C
-0.11 C
1918
4.5 C
-0.29 C
1935
5.4 C
+0.64 C
1936
5.7 C
+0.95 C
1937
5.0 C
+0.26 C
1938
4.9 C
+0.15 C
1939
4.6 C
-0.14 C
1940
5.1 C
+0.36 C
1941
4.4 C
-0.40 C
1943
4.5 C
-0.27 C
1944
4.3 C
-0.46 C
1945
4.2 C
-0.60 C
1946
5.1 C
+0.29 C
1947
4.2 C
-0.55 C
1949
4.7 C
-0.12 C
1950
4.9 C
+0.10 C
1951
4.0 C
-0.77 C
1952
4.1 C
-0.72 C
1953
5.0 C
+0.26 C
1954
6.0 C
+1.25 C
1955
3.8 C
-0.96 C
1956
4.6 C
-0.19 C
1957
4.3 C
-0.52 C
1958
5.2 C
+0.43 C
1960
5.3 C
+0.48 C
1961
4.8 C
+0.01 C
1962
5.2 C
+0.38 C
1963
5.6 C
+0.79 C
1964
3.9 C
-0.88 C
1965
4.9 C
+0.13 C
1967
5.2 C
+0.43 C
1968
4.3 C
-0.46 C
1969
5.1 C
+0.27 C
1970
4.6 C
-0.19 C
1971
4.6 C
-0.14 C
1973
4.5 C
-0.26 C
1974
4.9 C
+0.10 C
1975
4.4 C
-0.36 C
1976
5.3 C
+0.48 C
The fitted trend in annual mean temperature here over 1914 to 1976 is -0.02 C (-0.12 to 0.08) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: -0.03 F (-0.21 to 0.14) per decade. The slope is a straight line fitted to 41 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Aspen
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
-0.02 C (-0.12 to 0.08) per decade
-0.03 F (-0.21 to 0.14) per decade
1914 to 1976
41
Not clearly different from zero
Mean daily maximum
-0.09 C (-0.23 to 0.04) per decade
-0.2 F (-0.4 to 0.1) per decade
1914 to 1976
41
Not clearly different from zero
Mean daily minimum
0.1 C (-0.1 to 0.2) per decade
0.1 F (-0.2 to 0.4) per decade
1914 to 1976
41
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
1899 to 1979
Yearly extremes at Aspen: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
34.4 C (93.9 F)
1917
31.1 C (88.0 F)
52
Coldest night (TNn)
-38.3 C (-36.9 F)
1943
-28.0 C (-18.5 F)
52
Wettest day (Rx1day)
52.3 mm (2.1 in)
1966
25.0 mm (1.0 in)
54
Wettest five days (Rx5day)
89.6 mm (3.5 in)
1966
40.7 mm (1.6 in)
54
Longest dry spell (CDD)
45 days
1915
24 days
54
Hottest day (TXx)
The hottest day of the year at Aspen, 1899 to 1979. The record is 34.4 C (93.9 F) in 1917, marked on the chart; the median year is 31.1 C (88.0 F).
Hottest day (TXx) at Aspen by year
Year
Hottest day (TXx)
1899
n/a
1900
n/a
1914
31.1 C (88.0 F)
1915
29.4 C (84.9 F)
1916
29.4 C (84.9 F)
1917
34.4 C (93.9 F)
1918
31.1 C (88.0 F)
1919
30.6 C (87.1 F)
1934
32.8 C (91.0 F)
1935
32.2 C (90.0 F)
1936
31.7 C (89.1 F)
1937
29.4 C (84.9 F)
1938
30.6 C (87.1 F)
1939
33.9 C (93.0 F)
1940
32.2 C (90.0 F)
1941
31.1 C (88.0 F)
1942
31.7 C (89.1 F)
1943
31.1 C (88.0 F)
1944
31.7 C (89.1 F)
1945
29.4 C (84.9 F)
1946
31.1 C (88.0 F)
1947
31.7 C (89.1 F)
1948
30.6 C (87.1 F)
1949
28.9 C (84.0 F)
1950
28.9 C (84.0 F)
1951
29.4 C (84.9 F)
1952
30.0 C (86.0 F)
1953
29.4 C (84.9 F)
1954
33.9 C (93.0 F)
1955
30.0 C (86.0 F)
1956
29.4 C (84.9 F)
1957
29.4 C (84.9 F)
1958
31.7 C (89.1 F)
1959
32.2 C (90.0 F)
1960
31.7 C (89.1 F)
1961
29.4 C (84.9 F)
1962
31.1 C (88.0 F)
1963
31.1 C (88.0 F)
1964
30.6 C (87.1 F)
1965
28.9 C (84.0 F)
1966
30.6 C (87.1 F)
1967
29.4 C (84.9 F)
1968
31.1 C (88.0 F)
1969
33.3 C (91.9 F)
1970
31.1 C (88.0 F)
1971
31.7 C (89.1 F)
1972
32.2 C (90.0 F)
1973
31.1 C (88.0 F)
1974
32.2 C (90.0 F)
1975
31.1 C (88.0 F)
1976
32.2 C (90.0 F)
1977
31.7 C (89.1 F)
1978
32.8 C (91.0 F)
1979
31.1 C (88.0 F)
Coldest night (TNn)
The coldest night of the year at Aspen, 1899 to 1979. The record is -38.3 C (-36.9 F) in 1943, marked on the chart; the median year is -28.0 C (-18.5 F).
Coldest night (TNn) at Aspen by year
Year
Coldest night (TNn)
1899
n/a
1900
n/a
1914
-25.0 C (-13.0 F)
1915
-29.4 C (-20.9 F)
1916
-30.6 C (-23.1 F)
1917
-29.4 C (-20.9 F)
1918
-27.8 C (-18.0 F)
1919
-31.7 C (-25.1 F)
1934
-21.1 C (-6.0 F)
1935
-31.1 C (-24.0 F)
1936
-27.2 C (-17.0 F)
1937
-31.7 C (-25.1 F)
1938
-24.4 C (-11.9 F)
1939
-28.9 C (-20.0 F)
1940
-33.9 C (-29.0 F)
1941
-24.4 C (-11.9 F)
1942
-32.8 C (-27.0 F)
1943
-38.3 C (-36.9 F)
1944
-26.7 C (-16.1 F)
1945
-27.2 C (-17.0 F)
1946
-28.3 C (-18.9 F)
1947
-32.8 C (-27.0 F)
1948
-25.0 C (-13.0 F)
1949
-29.4 C (-20.9 F)
1950
-28.3 C (-18.9 F)
1951
-34.4 C (-29.9 F)
1952
-28.9 C (-20.0 F)
1953
-25.0 C (-13.0 F)
1954
-24.4 C (-11.9 F)
1955
-31.1 C (-24.0 F)
1956
-28.9 C (-20.0 F)
1957
-24.4 C (-11.9 F)
1958
-25.0 C (-13.0 F)
1959
-26.1 C (-15.0 F)
1960
-23.3 C (-9.9 F)
1961
-28.3 C (-18.9 F)
1962
-33.3 C (-27.9 F)
1963
-36.1 C (-33.0 F)
1964
-28.9 C (-20.0 F)
1965
-25.6 C (-14.1 F)
1966
-25.6 C (-14.1 F)
1967
-25.6 C (-14.1 F)
1968
-22.2 C (-8.0 F)
1969
-23.9 C (-11.0 F)
1970
-25.6 C (-14.1 F)
1971
-30.0 C (-22.0 F)
1972
-27.2 C (-17.0 F)
1973
-24.4 C (-11.9 F)
1974
-27.2 C (-17.0 F)
1975
-28.9 C (-20.0 F)
1976
-27.2 C (-17.0 F)
1977
-21.1 C (-6.0 F)
1978
-29.4 C (-20.9 F)
1979
-31.7 C (-25.1 F)
Wettest day (Rx1day)
The wettest day of the year at Aspen, 1899 to 1979. The record is 52.3 mm (2.1 in) in 1966, marked on the chart; the median year is 25.0 mm (1.0 in).
Wettest day (Rx1day) at Aspen by year
Year
Wettest day (Rx1day)
1899
25.7 mm (1.0 in)
1900
12.7 mm (0.5 in)
1914
20.6 mm (0.8 in)
1915
18.3 mm (0.7 in)
1916
18.3 mm (0.7 in)
1917
27.2 mm (1.1 in)
1918
33.3 mm (1.3 in)
1919
26.7 mm (1.1 in)
1934
40.6 mm (1.6 in)
1935
50.8 mm (2.0 in)
1936
40.6 mm (1.6 in)
1937
25.4 mm (1.0 in)
1938
23.6 mm (0.9 in)
1939
19.3 mm (0.8 in)
1940
16.3 mm (0.6 in)
1941
35.1 mm (1.4 in)
1942
24.4 mm (1.0 in)
1943
46.0 mm (1.8 in)
1944
16.8 mm (0.7 in)
1945
25.4 mm (1.0 in)
1946
19.6 mm (0.8 in)
1947
33.0 mm (1.3 in)
1948
20.8 mm (0.8 in)
1949
28.2 mm (1.1 in)
1950
17.8 mm (0.7 in)
1951
38.6 mm (1.5 in)
1952
14.2 mm (0.6 in)
1953
21.3 mm (0.8 in)
1954
19.3 mm (0.8 in)
1955
24.6 mm (1.0 in)
1956
16.8 mm (0.7 in)
1957
34.5 mm (1.4 in)
1958
16.8 mm (0.7 in)
1959
30.5 mm (1.2 in)
1960
15.2 mm (0.6 in)
1961
31.5 mm (1.2 in)
1962
26.2 mm (1.0 in)
1963
28.7 mm (1.1 in)
1964
32.8 mm (1.3 in)
1965
43.9 mm (1.7 in)
1966
52.3 mm (2.1 in)
1967
19.6 mm (0.8 in)
1968
20.8 mm (0.8 in)
1969
32.0 mm (1.3 in)
1970
21.1 mm (0.8 in)
1971
24.6 mm (1.0 in)
1972
26.2 mm (1.0 in)
1973
29.0 mm (1.1 in)
1974
21.3 mm (0.8 in)
1975
24.4 mm (1.0 in)
1976
17.0 mm (0.7 in)
1977
21.8 mm (0.9 in)
1978
25.9 mm (1.0 in)
1979
27.2 mm (1.1 in)
Wettest five days (Rx5day)
The wettest five days of the year at Aspen, 1899 to 1979. The record is 89.6 mm (3.5 in) in 1966, marked on the chart; the median year is 40.7 mm (1.6 in).
Wettest five days (Rx5day) at Aspen by year
Year
Wettest five days (Rx5day)
1899
74.7 mm (2.9 in)
1900
14.5 mm (0.6 in)
1914
43.7 mm (1.7 in)
1915
36.9 mm (1.5 in)
1916
46.1 mm (1.8 in)
1917
34.1 mm (1.3 in)
1918
45.0 mm (1.8 in)
1919
39.4 mm (1.6 in)
1934
41.6 mm (1.6 in)
1935
54.9 mm (2.2 in)
1936
70.5 mm (2.8 in)
1937
40.4 mm (1.6 in)
1938
39.5 mm (1.6 in)
1939
26.9 mm (1.1 in)
1940
33.1 mm (1.3 in)
1941
35.6 mm (1.4 in)
1942
35.3 mm (1.4 in)
1943
61.9 mm (2.4 in)
1944
35.2 mm (1.4 in)
1945
44.4 mm (1.7 in)
1946
21.9 mm (0.9 in)
1947
53.2 mm (2.1 in)
1948
20.8 mm (0.8 in)
1949
38.9 mm (1.5 in)
1950
37.2 mm (1.5 in)
1951
83.1 mm (3.3 in)
1952
85.4 mm (3.4 in)
1953
31.3 mm (1.2 in)
1954
47.3 mm (1.9 in)
1955
49.5 mm (1.9 in)
1956
25.7 mm (1.0 in)
1957
59.9 mm (2.4 in)
1958
27.5 mm (1.1 in)
1959
49.0 mm (1.9 in)
1960
36.2 mm (1.4 in)
1961
82.5 mm (3.2 in)
1962
44.7 mm (1.8 in)
1963
33.8 mm (1.3 in)
1964
66.3 mm (2.6 in)
1965
88.4 mm (3.5 in)
1966
89.6 mm (3.5 in)
1967
36.1 mm (1.4 in)
1968
31.4 mm (1.2 in)
1969
64.0 mm (2.5 in)
1970
37.6 mm (1.5 in)
1971
37.6 mm (1.5 in)
1972
44.5 mm (1.8 in)
1973
40.4 mm (1.6 in)
1974
48.4 mm (1.9 in)
1975
40.9 mm (1.6 in)
1976
33.0 mm (1.3 in)
1977
36.8 mm (1.4 in)
1978
50.0 mm (2.0 in)
1979
79.5 mm (3.1 in)
Longest dry spell (CDD)
The longest dry spell of the year at Aspen, 1899 to 1979. The record is 45 days in 1915, marked on the chart; the median year is 24 days.
Longest dry spell (CDD) at Aspen by year
Year
Longest dry spell (CDD)
1899
24 days
1900
21 days
1914
37 days
1915
45 days
1916
38 days
1917
19 days
1918
18 days
1919
28 days
1934
18 days
1935
28 days
1936
27 days
1937
29 days
1938
23 days
1939
35 days
1940
24 days
1941
14 days
1942
39 days
1943
23 days
1944
25 days
1945
31 days
1946
22 days
1947
23 days
1948
24 days
1949
27 days
1950
25 days
1951
16 days
1952
41 days
1953
36 days
1954
22 days
1955
23 days
1956
25 days
1957
22 days
1958
29 days
1959
35 days
1960
26 days
1961
31 days
1962
25 days
1963
25 days
1964
14 days
1965
26 days
1966
24 days
1967
22 days
1968
16 days
1969
17 days
1970
17 days
1971
21 days
1972
23 days
1973
19 days
1974
22 days
1975
23 days
1976
41 days
1977
25 days
1978
27 days
1979
20 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
41 years with a frost
Across 41 years with a frost, the median last spring frost at Aspen falls on 16 June and the median first autumn frost on 9 September, which leaves a median of 87 days between them.
Fitted over all years, the growing season changes by +0.6 days per decade at this station.
Frost dates and growing season at Aspen
Measure
Median, all years
Earliest period
Recent period (1943 to 1976)
Recent against earliest
Fitted trend
Last spring frost
16 June
n/a
16 June
n/a
+0.1 days per decade
First autumn frost
9 September
n/a
4 September
n/a
+0.7 days per decade
Growing days
87 days
n/a
83 days
n/a
+0.6 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
45 years, 1914 to 1977
A day with at least 24.0 mm (0.9 in) of rain is expected about once in 2 years. A day with at least 63.0 mm (2.5 in) of rain is expected about once in 100 years.
Rainfall return levels at Aspen: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
24.0 mm (0.9 in)
5 years
32.4 mm (1.3 in)
10 years
38.6 mm (1.5 in)
25 years
47.5 mm (1.9 in)
50 years
54.9 mm (2.2 in)
Longer than the 45 years of record
100 years
63.0 mm (2.5 in)
Longer than the 45 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, 45 years of values from 1914 to 1977.
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 1966; 50.8 mm (2.0 in) in 1935; 46.0 mm (1.8 in) in 1943.
Station Changes
1 suspected
One change was suspected in the annual mean temperature of Aspen, at 1960. Each is measured against neighbouring stations.
Relative to 5 neighbouring stations, the station's annual mean temperature from 1960 ran 0.4 C (0.7 F) higher than in the years before (likely change).
Suspected changes in the annual mean temperature at Aspen, against neighbouring stations
Year
Shift (C)
Shift (F)
Strength
Neighbours
1960
+0.4
+0.7
likely
5
Possible change at the station (a move, a new instrument or a new site); the record is kept as measured. A "likely" change has a larger test statistic than a "possible" one. Neither says why the station differs from its neighbours. How changes are found, and the largest ones.
Download the Data
Data for Aspen standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Aspen 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.