September
September · May · October
United States · 1991–2020
September leads for comfortable weather in Alta Vista: typically 27.1°C by day, 13.9°C at night, with 81 mm of rain. Based on measured 1991–2020 NOAA station history.
September · May · October
June · July · August
October · April · September
The weakest month is January, scoring 5 against September’s 78 — days reach only 4.4°C, 20° below the 24°C the score treats as ideal, and nights drop to -7.5°C.
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 | 4.4°C | -7.5°C | 17 mm | 3.5 | 9 h 43 | 5 | Strong coverage |
| February | 7.1°C | -5.4°C | 32 mm | 3.7 | 10 h 41 | 7 | Strong coverage |
| March | 13.2°C | 0.2°C | 59 mm | 5.6 | 11 h 50 | 32 | Strong coverage |
| April | 18.8°C | 6°C | 86 mm | 7.4 | 13 h 10 | 56 | Strong coverage |
| May | 23.8°C | 12.2°C | 135 mm | 9.7 | 14 h 16 | 74 | Strong coverage |
| June | 29.2°C | 17.6°C | 119 mm | 7.6 | 14 h 52 | 62 | Strong coverage |
| July | 32.1°C | 20.2°C | 112 mm | 7.6 | 14 h 38 | 49 | Strong coverage |
| August | 31.4°C | 19°C | 109 mm | 7.6 | 13 h 41 | 54 | Strong coverage |
| September | 27.1°C | 13.9°C | 81 mm | 6.3 | 12 h 24 | 78 | Strong coverage |
| October | 20.5°C | 6.7°C | 61 mm | 5.8 | 11 h 07 | 67 | Strong coverage |
| November | 12.7°C | 0.1°C | 41 mm | 4.1 | 10 h | 34 | Strong coverage |
| December | 6°C | -5.2°C | 29 mm | 3.8 | 9 h 27 | 5 | Strong coverage |
What has changed
Each bar compares the 2011–2025 daytime average for that month against the same month in 1961–1990, measured at the same station. Months where the older record is too thin to compare are left blank.
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 24.4°C11 Jan 1990 | -27.2°C20 Jan 1985 | 29 mm3 Jan 1971 | 49 mm2024 · driest 0 mm in 1986 | 61 |
| February | 26.7°C21 Feb 1981 | -30.6°C1 Feb 1979 | 56 mm21 Feb 1997 | 91 mm2001 · driest 0 mm in 1991 | 62 |
| March | 34.4°C22 Mar 2026 | -22.8°C4 Mar 1978 | 64 mm14 Mar 1995 | 202 mm1973 · driest 2 mm in 1966 | 61 |
| April | 35.0°C14 Apr 2006 | -14.4°C3 Apr 1975 | 110 mm1 Apr 1967 | 231 mm1999 · driest 11 mm in 1989 | 61 |
| May | 37.2°C31 May 1998 | -1.1°C3 May 1976 | 111 mm22 May 1971 | 344 mm2015 · driest 20 mm in 2009 | 60 |
| June | 44.4°C28 Jun 1980 | 5.0°C1 Jun 2012 | 134 mm1 Jun 1996 | 329 mm1967 · driest 10 mm in 1980 | 62 |
| July | 45.6°C11 Jul 1980 | 7.8°C5 Jul 1972 | 93 mm4 Jul 1983 | 387 mm1993 · driest 0 mm in 1975 | 62 |
| August | 43.3°C30 Aug 1984 | 7.2°C26 Aug 2025 | 115 mm31 Aug 2003 | 269 mm2005 · driest 1 mm in 1971 | 62 |
| September | 42.2°C3 Sep 2000 | -2.2°C30 Sep 1984 | 118 mm3 Sep 2021 | 249 mm1973 · driest 15 mm in 1990 | 61 |
| October | 35.6°C4 Oct 2006 | -9.4°C31 Oct 1993 | 107 mm11 Oct 1973 | 166 mm2002 · driest 5 mm in 1999 | 62 |
| November | 30.0°C9 Nov 2006 | -18.3°C28 Nov 1976 | 93 mm16 Nov 1964 | 184 mm1998 · driest 0 mm in 1989 | 62 |
| December | 23.9°C29 Dec 1984 | -31.1°C24 Dec 1989 | 51 mm30 Dec 1972 | 94 mm2007 · driest 0 mm in 2019 | 61 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 29 | <1 | 2 |
| February | <1 | 0 | 24 | 1 | 2 |
| March | 2 | 0 | 17 | 2 | <1 |
| April | 6 | 1 | 4 | 3 | <1 |
| May | 15 | 5 | <1 | 4 | 0 |
| June | 26 | 14 | 0 | 4 | 0 |
| July | 30 | 22 | 0 | 3 | 0 |
| August | 29 | 20 | 0 | 3 | 0 |
| September | 21 | 10 | <1 | 3 | 0 |
| October | 9 | 2 | 4 | 2 | 0 |
| November | 1 | 0 | 16 | 1 | <1 |
| December | 0 | 0 | 27 | <1 | 2 |
The best month has moved. On the 1961–1990 numbers the strongest month here was May (scoring 81); on 2011–2025 it is September (81). Both are scored the same way, from the same station — only the climate underneath changed.
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | 1% | 11% | 1% | 5% | 0.1–7.3°C |
| February | 6% | 12% | 3% | 6% | 1.3–11.3°C |
| March | 20% | 18% | 7% | 16% | 9.2–15.8°C |
| April | 37% | 24% | 9% | 24% | 16.5–21.6°C |
| May | 56% | 30% | 13% | 37% | 21.4–25.6°C |
| June | 73% | 26% | 12% | 29% | 26.8–30.9°C |
| July | 77% | 23% | 10% | 22% | 30.0–34.4°C |
| August | 76% | 24% | 9% | 24% | 28.7–34.5°C |
| September | 73% | 21% | 9% | 20% | 24.3–29.8°C |
| October | 49% | 18% | 7% | 17% | 18.0–22.5°C |
| November | 16% | 14% | 5% | 9% | 9.0–16.1°C |
| December | 2% | 12% | 3% | 6% | 2.6–8.9°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