Record envelope, standing records and threshold days for Mason Dam (USC00355258), Oregon, United States, with 32 years of record.
Key Facts for Mason Dam
Mason Dam (USC00355258) is a weather station in Oregon, United States at 44.67 latitude and -117.99 longitude, 1,189 m (3,900 ft) above sea level.
The station reports from 1969 to 2000, 32 years of record.
1,464 records set at Mason Dam still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Mason Dam set a daily record low minimum temperature of -12.8 C (9.0 F) on 18 November 2000.
About the Station
Location: Oregon, United States, 44.67 latitude, -117.99 longitude.
Elevation: 1,189 m (3,900 ft).
Period of record: 1969 to 2000, 32 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 Mason 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 Mason Dam, 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)
-33.3 C (-27.9 F)
n/a
n/a
Feb
17.8 C (64.0 F)
-40.0 C (-40.0 F)
n/a
n/a
Mar
22.8 C (73.0 F)
-22.8 C (-9.0 F)
n/a
n/a
Apr
29.4 C (84.9 F)
-14.4 C (6.1 F)
n/a
n/a
May
32.8 C (91.0 F)
-6.7 C (19.9 F)
n/a
n/a
Jun
34.4 C (93.9 F)
-5.6 C (21.9 F)
n/a
n/a
Jul
36.7 C (98.1 F)
-2.8 C (27.0 F)
n/a
n/a
Aug
36.7 C (98.1 F)
-3.3 C (26.1 F)
n/a
n/a
Sep
35.0 C (95.0 F)
-6.7 C (19.9 F)
n/a
n/a
Oct
29.4 C (84.9 F)
-15.0 C (5.0 F)
n/a
n/a
Nov
18.3 C (64.9 F)
-23.3 C (-9.9 F)
n/a
n/a
Dec
12.2 C (54.0 F)
-33.3 C (-27.9 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Mason Dam still stand. 1975 holds the most, with 76.
Standing records at Mason Dam by the year they were set
Year set
Standing records
1969
55
1970
70
1971
69
1972
62
1973
36
1974
66
1975
76
1976
49
1977
57
1978
49
1979
48
1980
37
1981
34
1982
32
1983
42
1984
46
1985
61
1986
47
1987
52
1988
33
1989
31
1990
40
1991
27
1992
45
1993
47
1994
29
1995
42
1996
53
1997
19
1998
34
1999
46
2000
30
Wettest Day of Each Month
Jan: 68.6 mm (2.7 in)
The wettest day on record for each calendar month at Mason Dam. The most was 68.6 mm (2.7 in) on 15 January 1971.
Record daily precipitation for each month at Mason Dam
Month
Record daily precipitation (mm)
Date
Jan
68.6 mm (2.7 in)
15 January 1971
Feb
42.7 mm (1.7 in)
22 February 1989
Mar
21.6 mm (0.9 in)
7 March 1986
Apr
21.3 mm (0.8 in)
6 April 1969
May
33.0 mm (1.3 in)
19 May 1991
Jun
50.8 mm (2.0 in)
3 June 1989
Jul
38.9 mm (1.5 in)
1 July 1982
Aug
52.1 mm (2.1 in)
31 August 1984
Sep
50.8 mm (2.0 in)
24 September 1976
Oct
23.6 mm (0.9 in)
29 October 1982
Nov
28.2 mm (1.1 in)
9 November 1985
Dec
29.0 mm (1.1 in)
2 December 1980
Period of Record Coverage
1969 to 2000
Complete yearUnder 90 percent of days
32 years of record at Mason Dam, 1969 to 2000. 4 years have data for under 90 percent of days and are left out of rankings: 1969, 1988, 1989, 1990.
Cooler than the station meanWarmer than the station mean
One stripe for each of 30 complete years at Mason Dam, 1970 to 2000. Blue stripes are years cooler than the station's own mean of 6.3 C (43.3 F); red stripes are warmer. The coolest year was 1985, at 4.1 C (39.3 F), and the warmest was 1992, at 7.7 C (45.9 F). The strongest colour marks a difference of 2.3 C (4.1 F).
Annual mean temperature at Mason Dam as warming stripes, 1970 to 2000
Year
Annual mean temperature
Difference from the station mean
1970
6.0 C
-0.34 C
1971
5.8 C
-0.50 C
1972
5.9 C
-0.39 C
1973
6.4 C
+0.12 C
1974
5.7 C
-0.64 C
1975
4.9 C
-1.41 C
1976
6.0 C
-0.29 C
1977
6.5 C
+0.22 C
1978
6.5 C
+0.21 C
1979
6.4 C
+0.13 C
1980
6.5 C
+0.24 C
1981
7.1 C
+0.84 C
1982
5.6 C
-0.70 C
1983
6.6 C
+0.29 C
1984
5.2 C
-1.08 C
1985
4.1 C
-2.24 C
1986
7.3 C
+0.96 C
1987
7.0 C
+0.75 C
1988
6.5 C
+0.24 C
1989
5.8 C
-0.46 C
1990
6.8 C
+0.50 C
1991
6.8 C
+0.51 C
1992
7.7 C
+1.44 C
1993
5.2 C
-1.05 C
1994
7.2 C
+0.90 C
1996
6.5 C
+0.17 C
1997
6.9 C
+0.63 C
1998
7.0 C
+0.75 C
1999
6.3 C
-0.04 C
2000
6.6 C
+0.29 C
The fitted trend in annual mean temperature here over 1970 to 2000 is 0.31 C (-0.01 to 0.62) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.55 F (-0.02 to 1.12) per decade. The slope is a straight line fitted to 30 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Mason Dam
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.31 C (-0.01 to 0.62) per decade
0.55 F (-0.02 to 1.12) per decade
1970 to 2000
30
Not clearly different from zero
Mean daily maximum
0.3 C (-0.1 to 0.6) per decade
0.5 F (-0.1 to 1.1) per decade
1970 to 2000
30
Not clearly different from zero
Mean daily minimum
0.36 C (-0.05 to 0.76) per decade
0.6 F (-0.1 to 1.4) per decade
1970 to 2000
30
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
1969 to 2000
Yearly extremes at Mason Dam: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
36.7 C (98.1 F)
1969
35.6 C (96.1 F)
32
Coldest night (TNn)
-40.0 C (-40.0 F)
1989
-26.9 C (-16.5 F)
32
Wettest day (Rx1day)
68.6 mm (2.7 in)
1971
26.9 mm (1.1 in)
32
Wettest five days (Rx5day)
112.3 mm (4.4 in)
1971
42.5 mm (1.7 in)
32
Longest dry spell (CDD)
80 days
1987
35 days
32
Hottest day (TXx)
The hottest day of the year at Mason Dam, 1969 to 2000. The record is 36.7 C (98.1 F) in 1969, marked on the chart; the median year is 35.6 C (96.1 F).
Hottest day (TXx) at Mason Dam by year
Year
Hottest day (TXx)
1969
36.7 C (98.1 F)
1970
35.6 C (96.1 F)
1971
34.4 C (93.9 F)
1972
36.1 C (97.0 F)
1973
34.4 C (93.9 F)
1974
35.0 C (95.0 F)
1975
35.6 C (96.1 F)
1976
33.3 C (91.9 F)
1977
35.6 C (96.1 F)
1978
35.6 C (96.1 F)
1979
34.4 C (93.9 F)
1980
36.7 C (98.1 F)
1981
35.0 C (95.0 F)
1982
33.3 C (91.9 F)
1983
35.0 C (95.0 F)
1984
34.4 C (93.9 F)
1985
35.6 C (96.1 F)
1986
34.4 C (93.9 F)
1987
35.0 C (95.0 F)
1988
35.6 C (96.1 F)
1989
33.3 C (91.9 F)
1990
36.7 C (98.1 F)
1991
36.1 C (97.0 F)
1992
36.1 C (97.0 F)
1993
32.2 C (90.0 F)
1994
36.1 C (97.0 F)
1995
33.9 C (93.0 F)
1996
35.6 C (96.1 F)
1997
33.9 C (93.0 F)
1998
35.6 C (96.1 F)
1999
36.1 C (97.0 F)
2000
36.1 C (97.0 F)
Coldest night (TNn)
The coldest night of the year at Mason Dam, 1969 to 2000. The record is -40.0 C (-40.0 F) in 1989, marked on the chart; the median year is -26.9 C (-16.5 F).
Coldest night (TNn) at Mason Dam by year
Year
Coldest night (TNn)
1969
-20.0 C (-4.0 F)
1970
-22.2 C (-8.0 F)
1971
-27.2 C (-17.0 F)
1972
-29.4 C (-20.9 F)
1973
-25.0 C (-13.0 F)
1974
-30.6 C (-23.1 F)
1975
-27.2 C (-17.0 F)
1976
-26.7 C (-16.1 F)
1977
-24.4 C (-11.9 F)
1978
-31.7 C (-25.1 F)
1979
-32.2 C (-26.0 F)
1980
-27.8 C (-18.0 F)
1981
-17.8 C (0.0 F)
1982
-31.1 C (-24.0 F)
1983
-33.3 C (-27.9 F)
1984
-28.9 C (-20.0 F)
1985
-34.4 C (-29.9 F)
1986
-19.4 C (-2.9 F)
1987
-27.8 C (-18.0 F)
1988
-28.3 C (-18.9 F)
1989
-40.0 C (-40.0 F)
1990
-32.2 C (-26.0 F)
1991
-23.3 C (-9.9 F)
1992
-21.7 C (-7.1 F)
1993
-26.7 C (-16.1 F)
1994
-25.0 C (-13.0 F)
1995
-26.1 C (-15.0 F)
1996
-33.9 C (-29.0 F)
1997
-20.0 C (-4.0 F)
1998
-23.3 C (-9.9 F)
1999
-23.3 C (-9.9 F)
2000
-21.7 C (-7.1 F)
Wettest day (Rx1day)
The wettest day of the year at Mason Dam, 1969 to 2000. The record is 68.6 mm (2.7 in) in 1971, marked on the chart; the median year is 26.9 mm (1.1 in).
Wettest day (Rx1day) at Mason Dam by year
Year
Wettest day (Rx1day)
1969
21.3 mm (0.8 in)
1970
24.9 mm (1.0 in)
1971
68.6 mm (2.7 in)
1972
18.3 mm (0.7 in)
1973
18.3 mm (0.7 in)
1974
27.9 mm (1.1 in)
1975
19.6 mm (0.8 in)
1976
50.8 mm (2.0 in)
1977
19.3 mm (0.8 in)
1978
26.9 mm (1.1 in)
1979
18.8 mm (0.7 in)
1980
29.0 mm (1.1 in)
1981
29.5 mm (1.2 in)
1982
38.9 mm (1.5 in)
1983
26.9 mm (1.1 in)
1984
52.1 mm (2.1 in)
1985
28.2 mm (1.1 in)
1986
30.0 mm (1.2 in)
1987
17.8 mm (0.7 in)
1988
16.0 mm (0.6 in)
1989
50.8 mm (2.0 in)
1990
20.1 mm (0.8 in)
1991
33.0 mm (1.3 in)
1992
21.8 mm (0.9 in)
1993
29.5 mm (1.2 in)
1994
27.9 mm (1.1 in)
1995
21.1 mm (0.8 in)
1996
13.5 mm (0.5 in)
1997
20.6 mm (0.8 in)
1998
33.8 mm (1.3 in)
1999
17.0 mm (0.7 in)
2000
27.9 mm (1.1 in)
Wettest five days (Rx5day)
The wettest five days of the year at Mason Dam, 1969 to 2000. The record is 112.3 mm (4.4 in) in 1971, marked on the chart; the median year is 42.5 mm (1.7 in).
Wettest five days (Rx5day) at Mason Dam by year
Year
Wettest five days (Rx5day)
1969
55.8 mm (2.2 in)
1970
44.0 mm (1.7 in)
1971
112.3 mm (4.4 in)
1972
28.7 mm (1.1 in)
1973
42.9 mm (1.7 in)
1974
71.6 mm (2.8 in)
1975
29.6 mm (1.2 in)
1976
52.6 mm (2.1 in)
1977
49.6 mm (2.0 in)
1978
42.1 mm (1.7 in)
1979
24.2 mm (1.0 in)
1980
47.1 mm (1.9 in)
1981
51.6 mm (2.0 in)
1982
59.9 mm (2.4 in)
1983
32.8 mm (1.3 in)
1984
69.6 mm (2.7 in)
1985
40.7 mm (1.6 in)
1986
40.9 mm (1.6 in)
1987
37.1 mm (1.5 in)
1988
31.5 mm (1.2 in)
1989
73.9 mm (2.9 in)
1990
39.7 mm (1.6 in)
1991
63.9 mm (2.5 in)
1992
39.5 mm (1.6 in)
1993
61.2 mm (2.4 in)
1994
37.3 mm (1.5 in)
1995
34.6 mm (1.4 in)
1996
35.1 mm (1.4 in)
1997
36.6 mm (1.4 in)
1998
47.8 mm (1.9 in)
1999
33.4 mm (1.3 in)
2000
49.2 mm (1.9 in)
Longest dry spell (CDD)
The longest dry spell of the year at Mason Dam, 1969 to 2000. The record is 80 days in 1987, marked on the chart; the median year is 35 days.
Longest dry spell (CDD) at Mason Dam by year
Year
Longest dry spell (CDD)
1969
47 days
1970
37 days
1971
24 days
1972
20 days
1973
67 days
1974
79 days
1975
21 days
1976
31 days
1977
31 days
1978
41 days
1979
37 days
1980
34 days
1981
36 days
1982
23 days
1983
18 days
1984
31 days
1985
31 days
1986
43 days
1987
80 days
1988
36 days
1989
33 days
1990
46 days
1991
37 days
1992
27 days
1993
46 days
1994
26 days
1995
39 days
1996
32 days
1997
19 days
1998
38 days
1999
73 days
2000
28 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 Mason Dam falls on 18 June and the median first autumn frost on 31 August, which leaves a median of 77 days between them.
Fitted over all years, the growing season changes by +8.3 days per decade at this station.
Frost dates and growing season at Mason Dam
Measure
Median, all years
Earliest period
Recent period (1970 to 2000)
Recent against earliest
Fitted trend
Last spring frost
18 June
n/a
18 June
n/a
-2.2 days per decade
First autumn frost
31 August
n/a
31 August
n/a
+6.0 days per decade
Growing days
77 days
n/a
77 days
n/a
+8.3 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
31 years, 1970 to 2000
A day with at least 24.9 mm (1.0 in) of rain is expected about once in 2 years. A day with at least 79.9 mm (3.1 in) of rain is expected about once in 100 years.
Rainfall return levels at Mason 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
24.9 mm (1.0 in)
5 years
35.0 mm (1.4 in)
10 years
43.2 mm (1.7 in)
25 years
55.7 mm (2.2 in)
50 years
66.9 mm (2.6 in)
Longer than the 31 years of record
100 years
79.9 mm (3.1 in)
Longer than the 31 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, 31 years of values from 1970 to 2000.
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: 68.6 mm (2.7 in) in 1971; 52.1 mm (2.1 in) in 1984; 50.8 mm (2.0 in) in 1976.
Download the Data
Data for Mason Dam standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Mason 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.