September
September · August · June
United States · 1991–2020
September leads for comfortable weather in East Washington: typically 23.4°C by day, 11.5°C at night, with 87 mm of rain. Based on measured 1991–2020 NOAA station history.
September · August · June
July · August · June
May · September · October
The weakest month is January, scoring 5 against September’s 80 — days reach only 1.9°C, 22° 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 | 1.9°C | -6.7°C | 84 mm | 11.9 | 9 h 36 | 5 | Good coverage |
| February | 3.4°C | -5.9°C | 60 mm | 9.3 | 10 h 37 | 5 | Good coverage |
| March | 9°C | -1.8°C | 86 mm | 10.4 | 11 h 49 | 6 | Good coverage |
| April | 16.4°C | 4.2°C | 80 mm | 10.5 | 13 h 13 | 42 | Good coverage |
| May | 21.4°C | 9.2°C | 108 mm | 11 | 14 h 23 | 63 | Good coverage |
| June | 25.9°C | 13.9°C | 107 mm | 11 | 15 h 01 | 75 | Good coverage |
| July | 27.7°C | 16.4°C | 93 mm | 9.4 | 14 h 46 | 71 | Good coverage |
| August | 27.3°C | 15.7°C | 83 mm | 8.4 | 13 h 45 | 76 | Good coverage |
| September | 23.4°C | 11.5°C | 87 mm | 8.4 | 12 h 24 | 80 | Good coverage |
| October | 16.9°C | 5.6°C | 65 mm | 8.3 | 11 h 04 | 51 | Good coverage |
| November | 10.3°C | 0.8°C | 78 mm | 9.2 | 9 h 54 | 18 | Good coverage |
| December | 4.2°C | -3.8°C | 81 mm | 10.6 | 9 h 19 | 5 | Good coverage |
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 21.1°C23 Jan 1999 | -31.7°C22 Jan 1984 | 49 mm6 Jan 2005 | 179 mm2005 · driest 16 mm in 1984 | 34 |
| February | 23.9°C27 Feb 2000 | -28.9°C7 Feb 1977 | 47 mm2 Feb 1988 | 113 mm2008 · driest 11 mm in 1978 | 35 |
| March | 27.8°C31 Mar 1998 | -17.8°C12 Mar 1984 | 41 mm14 Mar 1993 | 155 mm1994 · driest 33 mm in 2003 | 34 |
| April | 32.2°C18 Apr 1976 | -12.8°C2 Apr 1984 | 52 mm3 Apr 1977 | 156 mm2011 · driest 26 mm in 1997 | 37 |
| May | 34.4°C20 May 1977 | -6.7°C10 May 1983 | 54 mm26 May 1997 | 193 mm1997 · driest 31 mm in 1993 | 36 |
| June | 33.9°C23 Jun 1988 | 0.0°C9 Jun 2010 | 56 mm20 Jun 2007 | 191 mm2013 · driest 34 mm in 1999 | 33 |
| July | 37.8°C17 Jul 1988 | 3.3°C6 Jul 2009 | 100 mm21 Jul 1988 | 201 mm2003 · driest 32 mm in 1995 | 33 |
| August | 35.6°C14 Aug 2005 | -1.7°C29 Aug 1982 | 66 mm25 Aug 1998 | 179 mm1975 · driest 26 mm in 1993 | 33 |
| September | 35.0°C5 Sep 1983 | -1.1°C24 Sep 1983 | 132 mm18 Sep 2004 | 250 mm2004 · driest 12 mm in 1985 | 34 |
| October | 30.6°C7 Oct 2007 | -7.8°C28 Oct 1976 | 52 mm30 Oct 2012 | 132 mm2006 · driest 9 mm in 1982 | 34 |
| November | 26.7°C3 Nov 1985 | -20.0°C29 Nov 1976 | 54 mm20 Nov 2003 | 334 mm1985 · driest 20 mm in 1976 | 34 |
| December | 27.8°C4 Dec 1982 | -26.7°C27 Dec 1983 | 77 mm1 Dec 2010 | 173 mm2008 · driest 40 mm in 2006 | 33 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 27 | 3 | 8 |
| February | 0 | 0 | 24 | 2 | 7 |
| March | <1 | 0 | 20 | 3 | 4 |
| April | 3 | <1 | 7 | 3 | <1 |
| May | 9 | 1 | <1 | 4 | 0 |
| June | 19 | 5 | <1 | 3 | 0 |
| July | 25 | 8 | 0 | 3 | 0 |
| August | 24 | 7 | 0 | 3 | 0 |
| September | 12 | 2 | 0 | 3 | 0 |
| October | 3 | <1 | 4 | 2 | <1 |
| November | <1 | 0 | 15 | 2 | 1 |
| December | 0 | 0 | 25 | 2 | 6 |
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | <1% | 36% | 7% | 50% | -1.8–5.6°C |
| February | 1% | 31% | 6% | 40% | 0.0–6.9°C |
| March | 8% | 33% | 9% | 44% | 5.5–13.4°C |
| April | 22% | 34% | 9% | 47% | 14.0–18.2°C |
| May | 43% | 35% | 12% | 49% | 18.4–25.1°C |
| June | 61% | 35% | 12% | 44% | 24.0–27.4°C |
| July | 70% | 30% | 10% | 34% | 26.1–30.0°C |
| August | 73% | 26% | 9% | 28% | 25.6–29.0°C |
| September | 60% | 27% | 9% | 34% | 21.9–25.4°C |
| October | 27% | 28% | 7% | 32% | 14.4–19.3°C |
| November | 6% | 32% | 9% | 43% | 7.1–14.1°C |
| December | <1% | 34% | 8% | 41% | 0.5–7.4°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