Climate data for San Francisco (downtown),[a] 1991–2020 normals,[b] extremes 1849–present
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °F (°C) 79
(26) 		81
(27) 		87
(31) 		94
(34) 		97
(36) 		103
(39) 		99
(37) 		98
(37) 		106
(41) 		102
(39) 		86
(30) 		76
(24) 		106
(41)
Mean maximum °F (°C) 67.1
(19.5) 		71.8
(22.1) 		76.4
(24.7) 		80.7
(27.1) 		81.4
(27.4) 		84.6
(29.2) 		80.5
(26.9) 		83.4
(28.6) 		90.8
(32.7) 		87.9
(31.1) 		75.8
(24.3) 		66.4
(19.1) 		94.0
(34.4)
Mean daily maximum °F (°C) 57.8
(14.3) 		60.4
(15.8) 		62.1
(16.7) 		63.0
(17.2) 		64.1
(17.8) 		66.5
(19.2) 		66.3
(19.1) 		67.9
(19.9) 		70.2
(21.2) 		69.8
(21.0) 		63.7
(17.6) 		57.9
(14.4) 		64.1
(17.8)
Daily mean °F (°C) 52.2
(11.2) 		54.2
(12.3) 		55.5
(13.1) 		56.4
(13.6) 		57.8
(14.3) 		59.7
(15.4) 		60.3
(15.7) 		61.7
(16.5) 		62.9
(17.2) 		62.1
(16.7) 		57.2
(14.0) 		52.5
(11.4) 		57.7
(14.3)
Mean daily minimum °F (°C) 46.6
(8.1) 		47.9
(8.8) 		48.9
(9.4) 		49.7
(9.8) 		51.4
(10.8) 		53.0
(11.7) 		54.4
(12.4) 		55.5
(13.1) 		55.6
(13.1) 		54.4
(12.4) 		50.7
(10.4) 		47.0
(8.3) 		51.3
(10.7)
Mean minimum °F (°C) 40.5
(4.7) 		42.0
(5.6) 		43.7
(6.5) 		45.0
(7.2) 		48.0
(8.9) 		50.1
(10.1) 		51.6
(10.9) 		52.9
(11.6) 		52.0
(11.1) 		49.9
(9.9) 		44.9
(7.2) 		40.7
(4.8) 		38.8
(3.8)
Record low °F (°C) 29
(−2) 		31
(−1) 		33
(1) 		40
(4) 		42
(6) 		46
(8) 		47
(8) 		46
(8) 		47
(8) 		43
(6) 		38
(3) 		27
(−3) 		27
(−3)
Average precipitation inches (mm) 4.40
(112) 		4.37
(111) 		3.15
(80) 		1.60
(41) 		0.70
(18) 		0.20
(5.1) 		0.01
(0.25) 		0.06
(1.5) 		0.10
(2.5) 		0.94
(24) 		2.60
(66) 		4.76
(121) 		22.89
(581)
Average precipitation days (≥ 0.01 in) 11.2 10.8 10.8 6.8 4.0 1.6 0.7 1.1 1.2 3.5 7.9 11.6 71.2
Average relative humidity (%) 80 77 75 72 72 71 75 75 73 71 75 78 75
Mean monthly sunshine hours 185.9 207.7 269.1 309.3 325.1 311.4 313.3 287.4 271.4 247.1 173.4 160.6 3,061.7
Percent possible sunshine 61 69 73 78 74 70 70 68 73 71 57 54 69
Average ultraviolet index 2 3 5 7 9 10 10 9 7 5 3 2 6
Source 1: NOAA (sun 1961–1974)[1][2][3][4]
Source 2: Met Office (humidity)[5], Weather Atlas (UV)[6]
  1. ^ The coordinates of the station are 37°46′14″N 122°25′37″W / 37.7706°N 122.4269°W / 37.7706; -122.4269. Precipitation, high temperature, low temperature, snow, and snow depth records date from October 1, 1849; June 1, 1874; January 1, 1875; January 1, 1876; and January 1, 1922; respectively.
  2. ^ Mean monthly maxima and minima (i.e. the expected highest and lowest temperature readings at any point during the year or given month) calculated based on data at said location from 1991 to 2020.
  1. ^ "NOAA Climate Data". National Oceanic and Atmospheric Administration. Retrieved February 6, 2019.
  2. ^ "Summary of Monthly Normals 1991–2020". National Oceanic and Atmospheric Administration. Retrieved May 5, 2021.
  3. ^ "Station Name: CA SAN FRANCISCO DWTN". National Oceanic and Atmospheric Administration. Retrieved March 18, 2014.
  4. ^ "San Francisco/Mission Dolores, CA Climate Normals 1961–1990". National Oceanic and Atmospheric Administration. Retrieved April 23, 2013.
  5. ^ "San Francisco holiday weather". Met Office. Retrieved September 18, 2017.
  6. ^ "Climate and monthly weather forecast San Francisco, CA". Retrieved August 16, 2022.
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