San Mateo Threshold Days by Year (USC00297918)

14 fixed thresholds counted per year at San Mateo (USC00297918): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for San Mateo Thresholds

San Mateo: nights with a minimum temperature at or below 0 C (32 F) in 21 years, most in 1970 with 194.
San Mateo: nights with a minimum temperature at or below -10 C (14 F) in 21 years, most in 1976 with 59.
San Mateo: days with 10 mm (0.39 in) or more of precipitation in 20 years, most in 1986 with 13.
San Mateo: days with a maximum temperature at or above 30 C (86 F) in 18 years, most in 1985 with 41.
14 fixed thresholds have at least one qualifying day at San Mateo.

Days at or above 30 C (86 F)

18 years with a qualifying day

Days per year at San Mateo with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 41 in 1985.

Days at or above 30 C (86 F) per year at San Mateo
Year	Days	Decade average
1967	7	7
1970	24	25.9
1971	28	25.9
1972	24	25.9
1973	23	25.9
1974	38	25.9
1975	10	25.9
1976	19	25.9
1977	32	25.9
1978	29	25.9
1979	32	25.9
1980	40	23.7
1981	28	23.7
1983	5	23.7
1984	8	23.7
1985	41	23.7
1986	25	23.7
1987	19	23.7

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

First to last qualifying date each year at San Mateo
Year	First date	Last date
1967	1967-07-01	1967-08-04
1970	1970-06-18	1970-08-29
1971	1971-06-15	1971-09-14
1972	1972-06-28	1972-08-03
1973	1973-06-09	1973-08-18
1974	1974-05-10	1974-09-10
1975	1975-06-13	1975-08-24
1976	1976-06-20	1976-08-13
1977	1977-06-01	1977-08-08
1978	1978-06-15	1978-08-01
1979	1979-06-13	1979-08-07
1980	1980-06-12	1980-08-10
1981	1981-06-09	1981-08-07
1983	1983-06-22	1983-09-17
1984	1984-05-25	1984-07-21
1985	1985-06-07	1985-08-30
1986	1986-06-13	1986-08-22
1987	1987-06-14	1987-08-20

Every Fixed Threshold

Fixed thresholds at San Mateo
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	18	41	1985	19
35 C (95 F): Days	6	3	1979	2
90 F (32.2 C): Days	13	18	1981	14
0 C (32 F): Ice days (max	17	23	1979	20
0 C (32 F): Frost days (min	21	194	1970	147
-10 C (14 F): Days with min	21	59	1976	30
-20 C (-4 F): Days with min	9	7	1977	3
-30 C (-22 F): Days with min	1	2	1971	2
20 C (68 F): Tropical nights (min	4	1	1970	2
10 mm (0.39 in): Days with 10 mm or more rain	20	13	1986	6
25 mm (0.98 in): Days with 25 mm or more rain	10	3	1967	3
50 mm (1.97 in): Days with 50 mm or more rain	1	1	1986	1
10 cm (3.9 in): Days with 10 cm or more snowfall	4	6	1987	6
25 cm (9.8 in): Days with 25 cm or more snowfall	3	1	1967	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1967.

Download the Data

Data for San Mateo 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).

San Mateo Threshold Days by Year (USC00297918)

Key Facts for San Mateo Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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