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San Mateo Weather Records (USC00047864)

Record envelope, standing records and threshold days for San Mateo (USC00047864), California, United States, with 73 years of record.

Key Facts for San Mateo

  • San Mateo (USC00047864) is a weather station in California, United States at 37.53 latitude and -122.30 longitude, 6 m (20 ft) above sea level.
  • The station reports from 1906 to 1978, 73 years of record.
  • 1,464 records set at San Mateo still stand.
  • Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
  • San Mateo set a daily record low minimum temperature of -2.8 C (27.0 F) on 31 December 1978.

About the Station

  • Location: California, United States, 37.53 latitude, -122.30 longitude.
  • Elevation: 6 m (20 ft).
  • Period of record: 1906 to 1978, 73 years.
  • Eligible elements: tmax, tmin, prcp, snow, snwd.

Daily Record Envelope and 2026

0 days at or beyond a record
Daily record high and record low at San Mateo, with 2026 drawn through them The band shows the record high and record low for each calendar day at San Mateo. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius. -1001020304050 JanFebMarAprMayJunJulAugSepOctNovDec
The band shows the record high and record low for each calendar day at San Mateo. 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 San Mateo, with 2026 drawn through them
MonthHighest record highLowest record low2026 highest maximum2026 lowest minimum
Jan25.6 C (78.1 F)-5.0 C (23.0 F)n/an/a
Feb26.7 C (80.1 F)-1.7 C (28.9 F)n/an/a
Mar31.1 C (88.0 F)-0.6 C (30.9 F)n/an/a
Apr31.7 C (89.1 F)-0.6 C (30.9 F)n/an/a
May36.7 C (98.1 F)2.2 C (36.0 F)n/an/a
Jun42.8 C (109.0 F)4.4 C (39.9 F)n/an/a
Jul42.2 C (108.0 F)5.6 C (42.1 F)n/an/a
Aug39.4 C (102.9 F)7.8 C (46.0 F)n/an/a
Sep41.7 C (107.1 F)4.4 C (39.9 F)n/an/a
Oct35.6 C (96.1 F)2.2 C (36.0 F)n/an/a
Nov31.7 C (89.1 F)-1.7 C (28.9 F)n/an/a
Dec25.6 C (78.1 F)-3.9 C (25.0 F)n/an/a

Which Years Hold Standing Records

1,464 standing records
Standing records at San Mateo by the year they were set 1,464 records at San Mateo still stand. 1949 holds the most, with 78. 0204060801907: 201934: 111935: 291936: 371937: 321938: 191939: 301940: 311941: 231942: 231943: 281944: 321946: 461947: 311948: 301949: 781950: 501951: 391952: 351953: 231954: 211955: 331956: 161957: 211958: 231959: 261960: 231961: 341962: 251963: 221964: 501965: 451966: 341967: 531968: 531969: 321970: 471971: 331972: 501973: 261974: 241975: 321976: 411977: 241978: 29190719381943194919541959196419691974
1,464 records at San Mateo still stand. 1949 holds the most, with 78.
Standing records at San Mateo by the year they were set
Year setStanding records
190720
193411
193529
193637
193732
193819
193930
194031
194123
194223
194328
194432
194646
194731
194830
194978
195050
195139
195235
195323
195421
195533
195616
195721
195823
195926
196023
196134
196225
196322
196450
196545
196634
196753
196853
196932
197047
197133
197250
197326
197424
197532
197641
197724
197829

All-Time Record Progression

2 new records
When San Mateo set new all-time records 2 all-time records were set at San Mateo between 8 September 1969 and 9 December 1972. Each dot is a new record. Record high minimum temperatureRecord low maximum temperature8 September 1969: Record high minimum temperature 22.2 C (72.0 F)9 December 1972: Record low maximum temperature 4.4 C (39.9 F)1970
2 all-time records were set at San Mateo between 8 September 1969 and 9 December 1972. Each dot is a new record.
When San Mateo set new all-time records
DateKindDetail
1969-09-08Record high minimum temperatureRecord high minimum temperature 22.2 C (72.0 F)
1972-12-09Record low maximum temperatureRecord low maximum temperature 4.4 C (39.9 F)

Wettest Day of Each Month

Jan: 102.9 mm (4.1 in)
Record daily precipitation for each month at San Mateo The wettest day on record for each calendar month at San Mateo. The most was 102.9 mm (4.1 in) on 3 January 1916. 050100150 Jan: 102.9 mm (4.1 in), 3 January 1916 Jan Feb: 45.2 mm (1.8 in), 11 February 1936 Feb Mar: 74.2 mm (2.9 in), 30 March 1940 Mar Apr: 62.0 mm (2.4 in), 2 April 1958 Apr May: 35.8 mm (1.4 in), 18 May 1957 May Jun: 19.3 mm (0.8 in), 23 June 1912 Jun Jul: 20.3 mm (0.8 in), 30 July 1966 Jul Aug: 11.2 mm (0.4 in), 19 August 1975 Aug Sep: 55.4 mm (2.2 in), 18 September 1959 Sep Oct: 88.6 mm (3.5 in), 14 October 1962 Oct Nov: 93.0 mm (3.7 in), 18 November 1950 Nov Dec: 94.5 mm (3.7 in), 23 December 1955 Dec
The wettest day on record for each calendar month at San Mateo. The most was 102.9 mm (4.1 in) on 3 January 1916.
Record daily precipitation for each month at San Mateo
MonthRecord daily precipitation (mm)Date
Jan102.9 mm (4.1 in)3 January 1916
Feb45.2 mm (1.8 in)11 February 1936
Mar74.2 mm (2.9 in)30 March 1940
Apr62.0 mm (2.4 in)2 April 1958
May35.8 mm (1.4 in)18 May 1957
Jun19.3 mm (0.8 in)23 June 1912
Jul20.3 mm (0.8 in)30 July 1966
Aug11.2 mm (0.4 in)19 August 1975
Sep55.4 mm (2.2 in)18 September 1959
Oct88.6 mm (3.5 in)14 October 1962
Nov93.0 mm (3.7 in)18 November 1950
Dec94.5 mm (3.7 in)23 December 1955

Period of Record Coverage

1907 to 1978
Days with data per year at San Mateo 45 years of record at San Mateo, 1907 to 1978. 6 years have data for under 90 percent of days and are left out of rankings: 1907, 1934, 1942, 1948, 1976, 1977. 1907: 30 of 365 days1934: 184 of 365 days1935: 365 of 365 days1936: 365 of 366 days1937: 364 of 365 days1938: 358 of 365 days1939: 365 of 365 days1940: 360 of 366 days1941: 333 of 365 days1942: 321 of 365 days1943: 361 of 365 days1944: 361 of 366 days1946: 357 of 365 days1947: 330 of 365 days1948: 244 of 366 days1949: 363 of 365 days1950: 364 of 365 days1951: 363 of 365 days1952: 365 of 366 days1953: 365 of 365 days1954: 364 of 365 days1955: 362 of 365 days1956: 361 of 366 days1957: 357 of 365 days1958: 358 of 365 days1959: 360 of 365 days1960: 357 of 366 days1961: 356 of 365 days1962: 365 of 365 days1963: 364 of 365 days1964: 351 of 366 days1965: 355 of 365 days1966: 338 of 365 days1967: 362 of 365 days1968: 365 of 366 days1969: 362 of 365 days1970: 365 of 365 days1971: 365 of 365 days1972: 365 of 366 days1973: 363 of 365 days1974: 342 of 365 days1975: 358 of 365 days1976: 319 of 366 days1977: 269 of 365 days1978: 344 of 365 days1940195019601970
45 years of record at San Mateo, 1907 to 1978. 6 years have data for under 90 percent of days and are left out of rankings: 1907, 1934, 1942, 1948, 1976, 1977.
Days with data per year at San Mateo
YearDays with dataShare of yearComplete
1907308%No
193418450%No
1935365100%Yes
1936365100%Yes
1937364100%Yes
193835898%Yes
1939365100%Yes
194036098%Yes
194133391%Yes
194232188%No
194336199%Yes
194436199%Yes
194635798%Yes
194733090%Yes
194824467%No
194936399%Yes
1950364100%Yes
195136399%Yes
1952365100%Yes
1953365100%Yes
1954364100%Yes
195536299%Yes
195636199%Yes
195735798%Yes
195835898%Yes
195936099%Yes
196035798%Yes
196135698%Yes
1962365100%Yes
1963364100%Yes
196435196%Yes
196535597%Yes
196633893%Yes
196736299%Yes
1968365100%Yes
196936299%Yes
1970365100%Yes
1971365100%Yes
1972365100%Yes
197336399%Yes
197434294%Yes
197535898%Yes
197631987%No
197726974%No
197834494%Yes

Latest Records

20
Latest records at San Mateo
DateStationRecordValueBeat old record byOld record stoodSignificance
31 December 1978San Mateo, USdaily low min-2.8 C (27.0 F)2.2 C (4.0 F)32 years22 of 100 (Routine)
30 December 1978San Mateo, USdaily low max (Tie)9.4 C (48.9 F)tie23 years3 of 100 (Routine)
25 December 1978San Mateo, USdaily low min (Tie)-1.1 C (30.0 F)tie29 years3 of 100 (Routine)
21 December 1978San Mateo, USdaily low min (Tie)-1.1 C (30.0 F)tie28 years3 of 100 (Routine)
8 December 1978San Mateo, USdaily low min-1.1 C (30.0 F)0.5 C (0.9 F)5 years9 of 100 (Routine)
7 December 1978San Mateo, USdaily low max10.0 C (50.0 F)0.6 C (1.1 F)29 years16 of 100 (Routine)
22 November 1978San Mateo, USdaily rain25.9 mm (1.0 in)15.0 mm (0.6 in)69 years41 of 100 (Notable)
22 November 1978San Mateo, USdaily low max (Tie)11.1 C (52.0 F)tie4 years2 of 100 (Routine)
15 November 1978San Mateo, USdaily low min1.7 C (35.1 F)1.6 C (2.9 F)40 years24 of 100 (Routine)
14 November 1978San Mateo, USdaily low min1.7 C (35.1 F)1.1 C (2.0 F)43 years22 of 100 (Routine)
13 November 1978San Mateo, USdaily low max11.1 C (52.0 F)1.1 C (2.0 F)13 years14 of 100 (Routine)
12 November 1978San Mateo, USdaily low max11.1 C (52.0 F)1.7 C (3.1 F)19 years17 of 100 (Routine)
11 November 1978San Mateo, USdaily low max13.3 C (55.9 F)0.6 C (1.1 F)40 years20 of 100 (Routine)
14 October 1978San Mateo, USdaily high max35.0 C (95.0 F)0.6 C (1.1 F)16 years13 of 100 (Routine)
13 October 1978San Mateo, USdaily high max35.0 C (95.0 F)2.8 C (5.0 F)1 year14 of 100 (Routine)
3 October 1978San Mateo, USdaily high max32.8 C (91.0 F)0.6 C (1.1 F)31 years17 of 100 (Routine)
2 October 1978San Mateo, USmonthly high max (Tie)35.6 C (96.1 F)tie26 years6 of 100 (Routine)
29 September 1978San Mateo, USdaily high max (Tie)34.4 C (93.9 F)tie12 years2 of 100 (Routine)
25 September 1978San Mateo, USdaily high min (Tie)15.6 C (60.1 F)tie12 years2 of 100 (Routine)
24 September 1978San Mateo, USdaily high max36.7 C (98.1 F)1.1 C (2.0 F)13 years13 of 100 (Routine)

Climate Trend

34 complete years, 1935 to 1978
Annual mean temperature at San Mateo as warming stripes, 1935 to 1978 One stripe for each of 34 complete years at San Mateo, 1935 to 1978. Blue stripes are years cooler than the station's own mean of 14.8 C (58.6 F); red stripes are warmer. The coolest year was 1949, at 13.3 C (56.0 F), and the warmest was 1978, at 15.8 C (60.5 F). The strongest colour marks a difference of 1.5 C (2.7 F). 1935: 14.6 C, -0.2 C from the station mean1936: 15.7 C, +0.9 C from the station mean1937: 14.7 C, 0.0 C from the station mean1938: 14.3 C, -0.4 C from the station mean1939: 14.9 C, +0.1 C from the station mean1940: 15.2 C, +0.4 C from the station mean1946: 14.2 C, -0.6 C from the station mean1949: 13.3 C, -1.4 C from the station mean1950: 14.5 C, -0.3 C from the station mean1951: 14.6 C, -0.2 C from the station mean1952: 14.1 C, -0.6 C from the station mean1953: 14.6 C, -0.2 C from the station mean1954: 14.4 C, -0.4 C from the station mean1955: 13.9 C, -0.9 C from the station mean1956: 14.2 C, -0.6 C from the station mean1957: 14.7 C, -0.1 C from the station mean1958: 15.4 C, +0.6 C from the station mean1959: 15.3 C, +0.5 C from the station mean1960: 14.6 C, -0.1 C from the station mean1961: 14.9 C, +0.2 C from the station mean1962: 14.8 C, 0.0 C from the station mean1963: 14.8 C, +0.1 C from the station mean1964: 14.7 C, -0.1 C from the station mean1965: 15.0 C, +0.2 C from the station mean1966: 15.4 C, +0.6 C from the station mean1967: 15.2 C, +0.5 C from the station mean1968: 15.5 C, +0.7 C from the station mean1969: 14.9 C, +0.1 C from the station mean1970: 15.0 C, +0.2 C from the station mean1971: 14.4 C, -0.3 C from the station mean1972: 14.7 C, 0.0 C from the station mean1973: 15.1 C, +0.4 C from the station mean1975: 14.6 C, -0.1 C from the station mean1978: 15.8 C, +1.0 C from the station mean193519401945195019551960196519701975
One stripe for each of 34 complete years at San Mateo, 1935 to 1978. Blue stripes are years cooler than the station's own mean of 14.8 C (58.6 F); red stripes are warmer. The coolest year was 1949, at 13.3 C (56.0 F), and the warmest was 1978, at 15.8 C (60.5 F). The strongest colour marks a difference of 1.5 C (2.7 F).
Annual mean temperature at San Mateo as warming stripes, 1935 to 1978
YearAnnual mean temperatureDifference from the station mean
193514.6 C-0.16 C
193615.7 C+0.92 C
193714.7 C-0.02 C
193814.3 C-0.43 C
193914.9 C+0.15 C
194015.2 C+0.44 C
194614.2 C-0.60 C
194913.3 C-1.43 C
195014.5 C-0.26 C
195114.6 C-0.20 C
195214.1 C-0.62 C
195314.6 C-0.21 C
195414.4 C-0.39 C
195513.9 C-0.86 C
195614.2 C-0.55 C
195714.7 C-0.06 C
195815.4 C+0.59 C
195915.3 C+0.52 C
196014.6 C-0.14 C
196114.9 C+0.16 C
196214.8 C+0.02 C
196314.8 C+0.06 C
196414.7 C-0.07 C
196515.0 C+0.19 C
196615.4 C+0.62 C
196715.2 C+0.47 C
196815.5 C+0.70 C
196914.9 C+0.09 C
197015.0 C+0.25 C
197114.4 C-0.33 C
197214.7 C-0.04 C
197315.1 C+0.37 C
197514.6 C-0.12 C
197815.8 C+1.05 C

The fitted trend in annual mean temperature here over 1935 to 1978 is 0.12 C (-0.03 to 0.26) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.2 F (-0.1 to 0.5) 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 San Mateo
MeasurePer decade (C)Per decade (F)PeriodComplete yearsReading
Annual mean temperature0.12 C (-0.03 to 0.26) per decade0.2 F (-0.1 to 0.5) per decade1935 to 197834Not clearly different from zero
Mean daily maximum0.1 C (-0.1 to 0.3) per decade0.2 F (-0.2 to 0.5) per decade1935 to 197834Not clearly different from zero
Mean daily minimum0.1 C (0.0 to 0.3) per decade0.3 F (-0.1 to 0.6) per decade1935 to 197834Not 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

1906 to 1978
Yearly extremes at San Mateo: the record and the median year
MeasureRecordYear of the recordMedian yearYears with a value
Hottest day (TXx)42.8 C (109.0 F)196136.7 C (98.1 F)45
Coldest night (TNn)-5.0 C (23.0 F)1937-0.6 C (30.9 F)45
Wettest day (Rx1day)102.9 mm (4.1 in)191643.7 mm (1.7 in)57
Wettest five days (Rx5day)240.3 mm (9.5 in)196281.8 mm (3.2 in)56
Longest dry spell (CDD)190 days1973113 days56

Hottest day (TXx)

Hottest day (TXx) at San Mateo by year The hottest day of the year at San Mateo, 1906 to 1978. The record is 42.8 C (109.0 F) in 1961, marked on the chart; the median year is 36.7 C (98.1 F). 30354045192019401960Record: 42.8 C (109.0 F) in 1961
The hottest day of the year at San Mateo, 1906 to 1978. The record is 42.8 C (109.0 F) in 1961, marked on the chart; the median year is 36.7 C (98.1 F).
Hottest day (TXx) at San Mateo by year
YearHottest day (TXx)
1906n/a
190731.7 C (89.1 F)
1908n/a
1909n/a
1910n/a
1911n/a
1912n/a
1913n/a
1914n/a
1915n/a
1916n/a
1917n/a
1918n/a
193436.1 C (97.0 F)
193535.6 C (96.1 F)
193636.1 C (97.0 F)
193737.8 C (100.0 F)
193833.9 C (93.0 F)
193937.8 C (100.0 F)
194033.9 C (93.0 F)
194133.9 C (93.0 F)
194235.6 C (96.1 F)
194338.3 C (100.9 F)
194439.4 C (102.9 F)
194637.8 C (100.0 F)
194736.7 C (98.1 F)
194835.6 C (96.1 F)
194935.0 C (95.0 F)
195037.2 C (99.0 F)
195136.1 C (97.0 F)
195237.8 C (100.0 F)
195336.7 C (98.1 F)
195436.7 C (98.1 F)
195535.0 C (95.0 F)
195636.1 C (97.0 F)
195736.7 C (98.1 F)
195835.6 C (96.1 F)
195936.7 C (98.1 F)
196040.6 C (105.1 F)
196142.8 C (109.0 F)
196236.1 C (97.0 F)
196336.1 C (97.0 F)
196435.6 C (96.1 F)
196532.2 C (90.0 F)
196636.1 C (97.0 F)
196736.7 C (98.1 F)
196839.4 C (102.9 F)
196933.9 C (93.0 F)
197038.3 C (100.9 F)
197141.7 C (107.1 F)
197242.2 C (108.0 F)
197339.4 C (102.9 F)
197436.7 C (98.1 F)
197536.7 C (98.1 F)
197640.0 C (104.0 F)
197738.3 C (100.9 F)
197837.2 C (99.0 F)

Coldest night (TNn)

Coldest night (TNn) at San Mateo by year The coldest night of the year at San Mateo, 1906 to 1978. The record is -5.0 C (23.0 F) in 1937, marked on the chart; the median year is -0.6 C (30.9 F). -5051015192019401960Record: -5.0 C (23.0 F) in 1937
The coldest night of the year at San Mateo, 1906 to 1978. The record is -5.0 C (23.0 F) in 1937, marked on the chart; the median year is -0.6 C (30.9 F).
Coldest night (TNn) at San Mateo by year
YearColdest night (TNn)
1906n/a
190711.1 C (52.0 F)
1908n/a
1909n/a
1910n/a
1911n/a
1912n/a
1913n/a
1914n/a
1915n/a
1916n/a
1917n/a
1918n/a
19342.2 C (36.0 F)
1935-1.1 C (30.0 F)
1936-2.2 C (28.0 F)
1937-5.0 C (23.0 F)
19381.1 C (34.0 F)
19390.6 C (33.1 F)
1940-1.7 C (28.9 F)
19410.0 C (32.0 F)
1942-0.6 C (30.9 F)
1943-2.8 C (27.0 F)
19440.0 C (32.0 F)
1946-0.6 C (30.9 F)
1947-1.7 C (28.9 F)
1948-2.2 C (28.0 F)
1949-3.9 C (25.0 F)
1950-2.8 C (27.0 F)
19510.0 C (32.0 F)
1952-0.6 C (30.9 F)
19530.0 C (32.0 F)
1954-0.6 C (30.9 F)
1955-1.7 C (28.9 F)
19560.0 C (32.0 F)
1957-0.6 C (30.9 F)
19580.6 C (33.1 F)
19590.0 C (32.0 F)
1960-1.7 C (28.9 F)
19610.6 C (33.1 F)
1962-1.1 C (30.0 F)
1963-0.6 C (30.9 F)
19641.7 C (35.1 F)
19650.0 C (32.0 F)
19661.1 C (34.0 F)
19670.6 C (33.1 F)
1968-1.1 C (30.0 F)
1969-0.6 C (30.9 F)
1970-0.6 C (30.9 F)
1971-0.6 C (30.9 F)
1972-3.9 C (25.0 F)
1973-1.7 C (28.9 F)
19741.1 C (34.0 F)
1975-2.8 C (27.0 F)
19760.0 C (32.0 F)
19771.1 C (34.0 F)
1978-2.8 C (27.0 F)

Wettest day (Rx1day)

Wettest day (Rx1day) at San Mateo by year The wettest day of the year at San Mateo, 1906 to 1978. The record is 102.9 mm (4.1 in) in 1916, marked on the chart; the median year is 43.7 mm (1.7 in). 0255075100125192019401960Record: 102.9 mm (4.1 in) in 1916
The wettest day of the year at San Mateo, 1906 to 1978. The record is 102.9 mm (4.1 in) in 1916, marked on the chart; the median year is 43.7 mm (1.7 in).
Wettest day (Rx1day) at San Mateo by year
YearWettest day (Rx1day)
190629.0 mm (1.1 in)
190744.5 mm (1.8 in)
190825.4 mm (1.0 in)
190963.5 mm (2.5 in)
191031.2 mm (1.2 in)
191196.0 mm (3.8 in)
191250.8 mm (2.0 in)
191337.3 mm (1.5 in)
191452.1 mm (2.1 in)
191555.1 mm (2.2 in)
1916102.9 mm (4.1 in)
191720.8 mm (0.8 in)
191818.5 mm (0.7 in)
193448.3 mm (1.9 in)
193529.5 mm (1.2 in)
193647.8 mm (1.9 in)
193746.7 mm (1.8 in)
193844.5 mm (1.8 in)
193943.2 mm (1.7 in)
194074.2 mm (2.9 in)
194129.2 mm (1.1 in)
194252.1 mm (2.1 in)
194350.0 mm (2.0 in)
194440.6 mm (1.6 in)
194651.6 mm (2.0 in)
194725.7 mm (1.0 in)
194823.9 mm (0.9 in)
194929.7 mm (1.2 in)
195093.0 mm (3.7 in)
195143.7 mm (1.7 in)
195248.3 mm (1.9 in)
195343.7 mm (1.7 in)
195438.4 mm (1.5 in)
195594.5 mm (3.7 in)
195640.4 mm (1.6 in)
195740.4 mm (1.6 in)
195862.0 mm (2.4 in)
195955.4 mm (2.2 in)
196042.4 mm (1.7 in)
196136.8 mm (1.4 in)
196288.6 mm (3.5 in)
196337.6 mm (1.5 in)
196456.1 mm (2.2 in)
196533.5 mm (1.3 in)
196625.9 mm (1.0 in)
196779.8 mm (3.1 in)
196871.1 mm (2.8 in)
196933.5 mm (1.3 in)
197053.6 mm (2.1 in)
197128.4 mm (1.1 in)
197230.7 mm (1.2 in)
197347.8 mm (1.9 in)
197440.6 mm (1.6 in)
197523.4 mm (0.9 in)
197654.1 mm (2.1 in)
197729.2 mm (1.1 in)
197849.3 mm (1.9 in)

Wettest five days (Rx5day)

Wettest five days (Rx5day) at San Mateo by year The wettest five days of the year at San Mateo, 1906 to 1978. The record is 240.3 mm (9.5 in) in 1962, marked on the chart; the median year is 81.8 mm (3.2 in). 0100200300192019401960Record: 240.3 mm (9.5 in) in 1962
The wettest five days of the year at San Mateo, 1906 to 1978. The record is 240.3 mm (9.5 in) in 1962, marked on the chart; the median year is 81.8 mm (3.2 in).
Wettest five days (Rx5day) at San Mateo by year
YearWettest five days (Rx5day)
190678.7 mm (3.1 in)
190798.5 mm (3.9 in)
190843.9 mm (1.7 in)
1909170.7 mm (6.7 in)
191050.4 mm (2.0 in)
1911206.2 mm (8.1 in)
191274.9 mm (2.9 in)
191394.0 mm (3.7 in)
1914102.1 mm (4.0 in)
191588.1 mm (3.5 in)
191643.4 mm (1.7 in)
1917n/a
191837.3 mm (1.5 in)
193454.1 mm (2.1 in)
193561.6 mm (2.4 in)
1936100.0 mm (3.9 in)
193793.4 mm (3.7 in)
1938121.9 mm (4.8 in)
193950.2 mm (2.0 in)
1940114.9 mm (4.5 in)
194164.1 mm (2.5 in)
194289.7 mm (3.5 in)
1943113.0 mm (4.4 in)
194477.2 mm (3.0 in)
194668.1 mm (2.7 in)
194737.9 mm (1.5 in)
194843.4 mm (1.7 in)
194955.1 mm (2.2 in)
1950161.6 mm (6.4 in)
1951120.5 mm (4.7 in)
1952129.8 mm (5.1 in)
195350.1 mm (2.0 in)
195465.3 mm (2.6 in)
1955191.8 mm (7.6 in)
195672.9 mm (2.9 in)
1957104.7 mm (4.1 in)
1958133.9 mm (5.3 in)
195978.0 mm (3.1 in)
196080.3 mm (3.2 in)
196177.8 mm (3.1 in)
1962240.3 mm (9.5 in)
1963104.8 mm (4.1 in)
196499.8 mm (3.9 in)
196560.9 mm (2.4 in)
196657.9 mm (2.3 in)
1967152.4 mm (6.0 in)
196896.0 mm (3.8 in)
196972.6 mm (2.9 in)
1970131.1 mm (5.2 in)
197170.0 mm (2.8 in)
197283.2 mm (3.3 in)
197386.0 mm (3.4 in)
197464.8 mm (2.6 in)
197557.9 mm (2.3 in)
197656.6 mm (2.2 in)
197799.5 mm (3.9 in)
1978129.1 mm (5.1 in)

Longest dry spell (CDD)

Longest dry spell (CDD) at San Mateo by year The longest dry spell of the year at San Mateo, 1906 to 1978. The record is 190 days in 1973, marked on the chart; the median year is 113 days. 050100150200192019401960Record: 190 days in 1973
The longest dry spell of the year at San Mateo, 1906 to 1978. The record is 190 days in 1973, marked on the chart; the median year is 113 days.
Longest dry spell (CDD) at San Mateo by year
YearLongest dry spell (CDD)
1906141 days
190780 days
1908124 days
1909179 days
1910157 days
1911173 days
191272 days
1913102 days
191442 days
191539 days
191618 days
1917n/a
191820 days
193484 days
1935132 days
1936113 days
193762 days
1938149 days
1939113 days
194097 days
1941159 days
1942105 days
1943172 days
1944141 days
194667 days
1947120 days
1948133 days
194973 days
195097 days
195170 days
1952100 days
1953133 days
1954148 days
1955188 days
1956132 days
1957128 days
195854 days
1959104 days
1960134 days
1961106 days
1962103 days
1963123 days
196482 days
1965111 days
196681 days
1967120 days
1968143 days
1969136 days
1970132 days
1971125 days
1972108 days
1973190 days
197484 days
197580 days
1976127 days
197774 days
1978135 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.

Rainfall Return Levels

46 years, 1907 to 1978

A day with at least 44.1 mm (1.7 in) of rain is expected about once in 2 years. A day with at least 118.5 mm (4.7 in) of rain is expected about once in 100 years.

Rainfall return levels at San Mateo: the daily rain expected about once in a given number of years
Expected about once inA day with at leastNote
2 years44.1 mm (1.7 in)
5 years60.4 mm (2.4 in)
10 years72.5 mm (2.9 in)
25 years89.5 mm (3.5 in)
50 years103.4 mm (4.1 in)Longer than the 46 years of record
100 years118.5 mm (4.7 in)Longer than the 46 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, 46 years of values from 1907 to 1978.

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: 96.0 mm (3.8 in) in 1911; 94.5 mm (3.7 in) in 1955; 93.0 mm (3.7 in) in 1950.

Download the Data

  • Data for San Mateo standing records by year: CSV or JSON. Field meanings are on the data page.
  • 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 2026-10-14 (14 October 2026). Records are computed by this site and are not official.

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