September
September · May · August
United States · 1991–2020
September leads for comfortable weather in San Jose: typically 26.4°C by day, 12°C at night, with 88 mm of rain. Based on measured 1991–2020 NOAA station history.
September · May · August
August · July · June
October · April · May
The weakest month is January, scoring 5 against September’s 77 — days reach only 0.8°C, 23° below the 24°C the score treats as ideal.
Month by month
The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.
| Month | Day | Night | Rain | Wet days | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|
| January | 0.8°C | -8.3°C | 54 mm | 6 | 9 h 35 | 5 | Good coverage |
| February | 4.7°C | -5.4°C | 43 mm | 5.2 | 10 h 36 | 5 | Good coverage |
| March | 11.2°C | -1°C | 51 mm | 6.7 | 11 h 49 | 23 | Good coverage |
| April | 18.8°C | 5.6°C | 98 mm | 9.4 | 13 h 13 | 51 | Good coverage |
| May | 23.8°C | 11.3°C | 115 mm | 9.9 | 14 h 23 | 75 | Good coverage |
| June | 28.6°C | 16.5°C | 116 mm | 8.7 | 15 h 02 | 66 | Good coverage |
| July | 30.1°C | 18.2°C | 117 mm | 7.3 | 14 h 47 | 59 | Good coverage |
| August | 29.4°C | 16.8°C | 85 mm | 6 | 13 h 46 | 69 | Good coverage |
| September | 26.4°C | 12°C | 88 mm | 6 | 12 h 24 | 77 | Good coverage |
| October | 19.7°C | 6.6°C | 80 mm | 7.1 | 11 h 04 | 61 | Good coverage |
| November | 11.1°C | 0.2°C | 74 mm | 6 | 9 h 53 | 23 | Good coverage |
| December | 2.9°C | -6°C | 52 mm | 5.5 | 9 h 19 | 5 | Good coverage |
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 21.1°C31 Jan 1989 | -31.1°C17 Jan 1977 | 62 mm8 Jan 2008 | 102 mm1993 · driest 2 mm in 1986 | 44 |
| February | 23.9°C26 Feb 1996 | -27.2°C6 Feb 1982 | 53 mm22 Feb 1990 | 102 mm1990 · driest 3 mm in 2004 | 46 |
| March | 30.6°C29 Mar 1986 | -22.2°C5 Mar 1978 | 51 mm13 Mar 1972 | 208 mm1973 · driest 0 mm in 2001 | 46 |
| April | 32.8°C25 Apr 1986 | -9.4°C6 Apr 1982 | 70 mm30 Apr 1970 | 186 mm1970 · driest 13 mm in 1971 | 43 |
| May | 35.6°C25 May 1967 | -1.7°C3 May 1976 | 99 mm17 May 1995 | 300 mm1995 · driest 5 mm in 1964 | 47 |
| June | 39.4°C25 Jun 1988 | 3.9°C2 Jun 2003 | 85 mm14 Jun 1990 | 252 mm1998 · driest 13 mm in 1971 | 48 |
| July | 40.0°C25 Jul 2005 | 7.2°C27 Jul 1962 | 104 mm29 Jul 2002 | 291 mm1992 · driest 5 mm in 1988 | 48 |
| August | 39.4°C20 Aug 1983 | 4.4°C28 Aug 1986 | 83 mm6 Aug 1991 | 189 mm1965 · driest 17 mm in 1992 | 46 |
| September | 37.2°C1 Sep 1984 | -2.2°C23 Sep 1995 | 124 mm14 Sep 1993 | 264 mm1993 · driest 0 mm in 2004 | 48 |
| October | 34.4°C4 Oct 2006 | -7.8°C26 Oct 1962 | 122 mm4 Oct 1991 | 223 mm1991 · driest 1 mm in 1964 | 45 |
| November | 27.8°C1 Nov 2000 | -20.6°C30 Nov 1964 | 122 mm5 Nov 2004 | 240 mm1985 · driest 8 mm in 1999 | 47 |
| December | 22.8°C3 Dec 1970 | -30.6°C22 Dec 1989 | 79 mm3 Dec 1982 | 185 mm1982 · driest 9 mm in 1976 | 48 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 26 | 2 | 4 |
| February | 0 | 0 | 23 | 1 | 3 |
| March | <1 | 0 | 17 | 2 | 1 |
| April | 4 | <1 | 4 | 4 | <1 |
| May | 12 | 3 | <1 | 3 | 0 |
| June | 23 | 11 | 0 | 4 | 0 |
| July | 26 | 14 | 0 | 3 | 0 |
| August | 26 | 13 | 0 | 3 | 0 |
| September | 17 | 7 | <1 | 3 | 0 |
| October | 6 | 1 | 4 | 3 | <1 |
| November | <1 | 0 | 15 | 2 | <1 |
| December | 0 | 0 | 24 | 2 | 3 |
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | <1% | 19% | 5% | 15% | -3.6–4.9°C |
| February | 1% | 20% | 5% | 16% | -0.6–7.9°C |
| March | 9% | 24% | 6% | 26% | 7.8–13.5°C |
| April | 31% | 30% | 11% | 38% | 15.5–21.5°C |
| May | 57% | 29% | 11% | 35% | 21.3–26.6°C |
| June | 72% | 28% | 11% | 29% | 27.3–30.8°C |
| July | 76% | 23% | 10% | 21% | 28.9–32.5°C |
| August | 79% | 20% | 9% | 17% | 27.4–31.1°C |
| September | 72% | 22% | 10% | 22% | 23.9–28.1°C |
| October | 40% | 22% | 8% | 21% | 17.4–21.1°C |
| November | 8% | 21% | 7% | 19% | 8.0–13.7°C |
| December | <1% | 20% | 6% | 19% | -1.1–6.5°C |
A warm and dry day reaches 20°C with under 1 mm of rain; a wet day gets 1 mm or more; a washout gets 10 mm or more. The week column is the share of seven-day stretches in that month, across the station’s whole daily record, that contained three or more wet days — the odds a week-long trip is rained on repeatedly, counted rather than modelled. The last column is the 10th to 90th percentile of that month’s daytime average across individual years: a narrow band means the average is what you will get, a wide one means the average is a midpoint between years that felt quite different.
The evidence behind this page