Mason Dam Threshold Days by Year (USC00355258)

14 fixed thresholds counted per year at Mason Dam (USC00355258): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Mason Dam Thresholds

Mason Dam: nights with a minimum temperature at or below 0 C (32 F) in 31 years, most in 1974 with 240.
Mason Dam: nights with a minimum temperature at or below -10 C (14 F) in 31 years, most in 1985 with 109.
Mason Dam: days with 10 mm (0.39 in) or more of precipitation in 31 years, most in 1981 with 16.
Mason Dam: nights with a minimum temperature at or below -20 C (-4 F) in 29 years, most in 1985 with 38.
14 fixed thresholds have at least one qualifying day at Mason Dam.

Days at or above 30 C (86 F)

28 years with a qualifying day

Days per year at Mason Dam with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 41 in 1970.

Days at or above 30 C (86 F) per year at Mason Dam
Year	Days	Decade average
1970	41	27.5
1971	38	27.5
1972	21	27.5
1973	33	27.5
1974	29	27.5
1975	19	27.5
1976	13	27.5
1977	28	27.5
1978	25	27.5
1979	28	27.5
1980	9	23.8
1981	32	23.8
1982	14	23.8
1983	18	23.8
1984	26	23.8
1985	29	23.8
1986	34	23.8
1987	28	23.8
1991	26	27.6
1992	30	27.6
1993	8	27.6
1994	38	27.6
1995	18	27.6
1996	38	27.6
1997	21	27.6
1998	40	27.6
1999	29	27.6
2000	31	31

For each year, a bar from the first to the last day at Mason Dam meeting 30 C (86 F).

First to last qualifying date each year at Mason Dam
Year	First date	Last date
1970	1970-06-04	1970-08-31
1971	1971-06-21	1971-08-29
1972	1972-05-31	1972-08-29
1973	1973-05-18	1973-09-06
1974	1974-06-12	1974-09-04
1975	1975-07-04	1975-09-07
1976	1976-06-29	1976-09-05
1977	1977-06-05	1977-09-04
1978	1978-07-09	1978-09-03
1979	1979-06-11	1979-09-18
1980	1980-07-21	1980-09-06
1981	1981-06-30	1981-09-18
1982	1982-07-25	1982-08-26
1983	1983-05-25	1983-08-17
1984	1984-05-29	1984-09-18
1985	1985-06-18	1985-08-26
1986	1986-05-26	1986-09-06
1987	1987-06-11	1987-09-24
1991	1991-07-03	1991-09-06
1992	1992-06-01	1992-09-30
1993	1993-05-12	1993-09-10
1994	1994-06-20	1994-09-23
1995	1995-06-27	1995-09-16
1996	1996-06-08	1996-09-12
1997	1997-07-06	1997-09-10
1998	1998-07-08	1998-09-17
1999	1999-05-25	1999-08-29
2000	2000-06-04	2000-09-14

Every Fixed Threshold

Fixed thresholds at Mason Dam
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	28	41	1970	31
35 C (95 F): Days	18	5	1998	5
90 F (32.2 C): Days	28	25	1994	17
0 C (32 F): Ice days (max	28	67	1985	24
0 C (32 F): Frost days (min	31	240	1974	194
-10 C (14 F): Days with min	31	109	1985	42
-20 C (-4 F): Days with min	29	38	1985	3
-30 C (-22 F): Days with min	9	8	1979	4
-40 C (-40 F): Days with min	1	0	n/a	1
10 mm (0.39 in): Days with 10 mm or more rain	31	16	1981	5
25 mm (0.98 in): Days with 25 mm or more rain	17	3	1984	1
50 mm (1.97 in): Days with 50 mm or more rain	4	1	1971	1
10 cm (3.9 in): Days with 10 cm or more snowfall	18	10	1983	4
25 cm (9.8 in): Days with 25 cm or more snowfall	2	1	1980	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1970.

Download the Data

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 2026-10-17 (17 October 2026). Threshold counts are computed by this site.

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

Mason Dam Threshold Days by Year (USC00355258)

Key Facts for Mason Dam Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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