September
September · June · May
United States · 1991–2020
September leads for comfortable weather in Inland: typically 25.8°C by day, 11.6°C at night, with 57 mm of rain. Based on measured 1991–2020 NOAA station history.
September · June · May
August · July · June
October · September · May
The weakest month is January, scoring 5 against September’s 83 — days reach only 2°C, 22° below the 24°C the score treats as ideal, and nights drop to -9.5°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 | 2°C | -9.5°C | 16 mm | 3.2 | 9 h 34 | 5 | Strong coverage |
| February | 4.4°C | -7.7°C | 21 mm | 3.4 | 10 h 35 | 5 | Strong coverage |
| March | 11.3°C | -2.5°C | 35 mm | 5.3 | 11 h 49 | 24 | Strong coverage |
| April | 17°C | 3°C | 78 mm | 7.3 | 13 h 14 | 45 | Strong coverage |
| May | 22.6°C | 9.6°C | 116 mm | 9.3 | 14 h 25 | 69 | Strong coverage |
| June | 28.4°C | 15.6°C | 98 mm | 8.6 | 15 h 04 | 71 | Strong coverage |
| July | 30.5°C | 18°C | 96 mm | 7.5 | 14 h 48 | 61 | Strong coverage |
| August | 29.2°C | 16.7°C | 86 mm | 7.3 | 13 h 47 | 69 | Strong coverage |
| September | 25.8°C | 11.6°C | 57 mm | 5.4 | 12 h 25 | 83 | Strong coverage |
| October | 18.3°C | 4.3°C | 51 mm | 5.2 | 11 h 03 | 58 | Strong coverage |
| November | 10.2°C | -2.7°C | 32 mm | 3.6 | 9 h 52 | 22 | Strong coverage |
| December | 3.5°C | -7.8°C | 23 mm | 3.5 | 9 h 17 | 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 | -34.4°C12 Jan 1912 | 43 mm23 Jan 1965 | 82 mm1960 · driest 0 mm in 1943 | 117 |
| February | 26.7°C25 Feb 1995 | -33.9°C16 Feb 2021 | 39 mm19 Feb 1971 | 71 mm1971 · driest 0 mm in 1921 | 115 |
| March | 35.6°C21 Mar 2026 | -26.1°C11 Mar 1998 | 72 mm13 Mar 2021 | 216 mm2021 · driest 0 mm in 1936 | 115 |
| April | 35.6°C23 Apr 1989 | -15.0°C3 Apr 1936 | 74 mm24 Apr 2007 | 177 mm1984 · driest 1 mm in 1989 | 116 |
| May | 40.6°C29 May 1934 | -5.6°C1 May 1909 | 99 mm23 May 1965 | 317 mm1965 · driest 12 mm in 1934 | 118 |
| June | 43.3°C26 Jun 1936 | 1.1°C4 Jun 1951 | 130 mm4 Jun 2015 | 297 mm1915 · driest 10 mm in 1911 | 120 |
| July | 46.7°C24 Jul 1936 | 7.2°C4 Jul 1915 | 101 mm6 Jul 1969 | 291 mm1993 · driest 4 mm in 1983 | 120 |
| August | 43.9°C23 Aug 1943 | 4.4°C30 Aug 1911 | 155 mm31 Aug 1969 | 250 mm1990 · driest 9 mm in 1919 | 119 |
| September | 40.6°C4 Sep 1945 | -3.3°C22 Sep 1995 | 107 mm3 Sep 1973 | 321 mm1973 · driest 5 mm in 1943 | 118 |
| October | 36.1°C5 Oct 1947 | -15.6°C27 Oct 1997 | 87 mm3 Oct 2013 | 161 mm2008 · driest 0 mm in 1933 | 119 |
| November | 30.0°C5 Nov 1945 | -21.7°C14 Nov 1940 | 82 mm16 Nov 1996 | 101 mm1996 · driest 0 mm in 1924 | 118 |
| December | 26.7°C23 Dec 1964 | -30.6°C23 Dec 1989 | 40 mm26 Dec 2018 | 125 mm1913 · driest 0 mm in 1922 | 118 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 30 | <1 | 5 |
| February | <1 | 0 | 26 | <1 | 5 |
| March | 1 | <1 | 22 | 1 | 3 |
| April | 4 | <1 | 9 | 2 | 1 |
| May | 12 | 4 | <1 | 4 | <1 |
| June | 24 | 12 | 0 | 3 | 0 |
| July | 29 | 18 | 0 | 4 | 0 |
| August | 27 | 14 | 0 | 3 | 0 |
| September | 18 | 8 | <1 | 2 | 0 |
| October | 5 | 1 | 6 | 2 | <1 |
| November | <1 | 0 | 22 | <1 | 2 |
| December | 0 | 0 | 30 | <1 | 4 |
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | <1% | 9% | 1% | 4% | -2.3–6.5°C |
| February | 3% | 12% | 2% | 8% | -0.2–9.3°C |
| March | 15% | 16% | 4% | 13% | 5.9–15.0°C |
| April | 34% | 23% | 8% | 25% | 14.2–20.3°C |
| May | 56% | 28% | 11% | 33% | 20.2–25.9°C |
| June | 71% | 28% | 11% | 30% | 26.2–31.8°C |
| July | 78% | 22% | 9% | 22% | 29.5–34.7°C |
| August | 78% | 22% | 9% | 19% | 28.2–33.8°C |
| September | 74% | 18% | 7% | 15% | 23.5–29.4°C |
| October | 48% | 14% | 5% | 10% | 16.5–22.6°C |
| November | 10% | 10% | 3% | 6% | 7.8–13.5°C |
| December | <1% | 10% | 2% | 5% | -0.5–7.3°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