September
September · June · August
77climate match
United States · 1991–2020
Best time to visit
Richland.
September leads for comfortable weather in Richland: typically 24.7°C by day, 11.4°C at night, with 98 mm of rain. Based on measured 1991–2020 NOAA station history.
Best comfortSeptember
Typical high24.7°C
Typical low11.4°C
Rain in September98 mm
July
July · August · June
68climate match
May
May · October · September
67climate match
The weakest month is January, scoring 5 against September’s 77 — days reach only 0.7°C, 23° below the 24°C the score treats as ideal.
Month by month
The whole year,
without the guesswork.
The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.
Jan
50.7° / -7.4°
Feb
52.7° / -7.3°
Mar
129.2° / -2.3°
Apr
3816.2° / 3°
May
6822.9° / 9.2°
Jun
7027.9° / 14.2°
Jul
6529.8° / 16.2°
Aug
6928.3° / 15.5°
Sep
7724.7° / 11.4°
Oct
4817.8° / 5.9°
Nov
139.4° / 0.6°
Dec
52.9° / -5.1°
| Month | Day | Night | Rain | Wet days | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|
| January | 0.7°C | -7.4°C | 69 mm | 11.3 | 9 h 24 | 5 | Strong coverage |
| February | 2.7°C | -7.3°C | 50 mm | 8.2 | 10 h 29 | 5 | Good coverage |
| March | 9.2°C | -2.3°C | 63 mm | 8 | 11 h 48 | 12 | Strong coverage |
| April | 16.2°C | 3°C | 96 mm | 10 | 13 h 18 | 38 | Strong coverage |
| May | 22.9°C | 9.2°C | 111 mm | 10.7 | 14 h 34 | 68 | Strong coverage |
| June | 27.9°C | 14.2°C | 107 mm | 9.3 | 15 h 16 | 70 | Strong coverage |
| July | 29.8°C | 16.2°C | 102 mm | 7.7 | 14 h 59 | 65 | Strong coverage |
| August | 28.3°C | 15.5°C | 113 mm | 9.1 | 13 h 54 | 69 | Strong coverage |
| September | 24.7°C | 11.4°C | 98 mm | 8.8 | 12 h 26 | 77 | Strong coverage |
| October | 17.8°C | 5.9°C | 99 mm | 10.2 | 10 h 59 | 48 | Strong coverage |
| November | 9.4°C | 0.6°C | 78 mm | 10.3 | 9 h 43 | 13 | Strong coverage |
| December | 2.9°C | -5.1°C | 72 mm | 10.5 | 9 h 05 | 5 | Good coverage |
What has changed
Richland runs +1.0°C
on the 1961–1990 baseline.
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.
Jan
+2.0
Feb—
Mar
+2.1
Apr
+0.3
May
+0.9
Jun
+1.0
Jul
+0.6
Aug
+0.2
Sep
+1.2
Oct
+0.7
Nov
+0.6
Dec—
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 18.9°C25 Jan 1950 | -29.4°C30 Jan 1951 | 94 mm19 Jan 1952 | 137 mm1952 · driest 1 mm in 2020 | 90 |
| February | 21.7°C28 Feb 2024 | -28.3°C3 Feb 1996 | 53 mm20 Feb 2018 | 116 mm1939 · driest 2 mm in 1987 | 89 |
| March | 30.0°C21 Mar 2012 | -26.1°C8 Mar 1943 | 65 mm19 Mar 1948 | 146 mm1991 · driest 0 mm in 2015 | 92 |
| April | 31.1°C18 Apr 2002 | -15.6°C7 Apr 1982 | 74 mm19 Apr 1975 | 214 mm2026 · driest 11 mm in 2004 | 94 |
| May | 34.4°C16 May 1998 | -5.6°C9 May 1947 | 81 mm31 May 1989 | 252 mm2004 · driest 15 mm in 2021 | 93 |
| June | 38.9°C1 Jun 1934 | -2.2°C27 Jun 1992 | 92 mm26 Jun 1978 | 236 mm1979 · driest 7 mm in 1984 | 94 |
| July | 42.2°C13 Jul 1936 | 4.4°C2 Jul 2001 | 106 mm3 Jul 2008 | 232 mm2011 · driest 3 mm in 1975 | 94 |
| August | 39.4°C5 Aug 1947 | 2.8°C7 Aug 1993 | 139 mm19 Aug 1939 | 265 mm1975 · driest 11 mm in 1976 | 90 |
| September | 37.8°C1 Sep 1953 | -3.9°C29 Sep 1942 | 154 mm14 Sep 2008 | 357 mm2008 · driest 0 mm in 1979 | 90 |
| October | 32.2°C6 Oct 1963 | -7.8°C27 Oct 1976 | 77 mm5 Oct 1941 | 249 mm1941 · driest 6 mm in 1952 | 92 |
| November | 26.1°C1 Nov 1950 | -21.7°C25 Nov 1950 | 60 mm5 Nov 1990 | 193 mm1990 · driest 10 mm in 1962 | 91 |
| December | 20.6°C5 Dec 2001 | -26.1°C31 Dec 1976 | 49 mm31 Dec 2019 | 148 mm1984 · driest 8 mm in 1943 | 87 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 25 | 2 | 9 |
| February | 0 | 0 | 24 | 1 | 6 |
| March | <1 | <1 | 19 | 2 | 2 |
| April | 3 | <1 | 9 | 3 | <1 |
| May | 11 | 3 | 1 | 4 | 0 |
| June | 23 | 11 | 0 | 4 | 0 |
| July | 27 | 14 | 0 | 3 | 0 |
| August | 26 | 9 | 0 | 3 | 0 |
| September | 15 | 5 | <1 | 3 | 0 |
| October | 4 | <1 | 4 | 3 | <1 |
| November | 0 | 0 | 14 | 2 | 2 |
| December | 0 | 0 | 25 | 2 | 7 |
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | 0% | 32% | 4% | 37% | -3.4–3.0°C |
| February | 0% | 28% | 5% | 29% | -1.7–5.6°C |
| March | 4% | 28% | 7% | 35% | 3.6–11.6°C |
| April | 17% | 34% | 10% | 43% | 12.2–18.1°C |
| May | 47% | 32% | 12% | 38% | 18.7–24.9°C |
| June | 67% | 31% | 12% | 36% | 24.8–29.3°C |
| July | 76% | 25% | 10% | 26% | 27.5–31.3°C |
| August | 74% | 26% | 10% | 28% | 26.3–30.0°C |
| September | 61% | 28% | 10% | 31% | 22.4–26.0°C |
| October | 28% | 29% | 9% | 36% | 15.2–20.0°C |
| November | 3% | 33% | 8% | 41% | 5.7–11.8°C |
| December | 0% | 32% | 6% | 39% | -1.3–5.1°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
Nearby, measured,
and named.
- Place identity
- GeoNames 5007115
- NOAA station
- USC00203504 · GULL LAKE BIOLOGICAL STN
- Station distance
- 6.1 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 20 usable years
- Daylight
- Calculated from latitude 42.38°, mid-month, sunrise to sunset including refraction. Not a station measurement.
- Important limit
- Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.