September
September · June · August
83climate match
United States · 1991–2020
Best time to visit
Rousseau.
September leads for comfortable weather in Rousseau: typically 25.5°C by day, 10°C at night, with 44 mm of rain. Based on measured 1991–2020 NOAA station history.
Best comfortSeptember
Typical high25.5°C
Typical low10°C
Rain in September44 mm
August
August · July · June
74climate match
September
September · May · October
79climate match
The weakest month is January, scoring 5 against September’s 83 — days reach only -1.4°C, 25° 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
5-1.4° / -12.4°
Feb
51.2° / -10.6°
Mar
107.9° / -5°
Apr
4015° / 0.9°
May
6421.1° / 7.3°
Jun
7426.9° / 13.2°
Jul
6631.5° / 16.6°
Aug
7330.5° / 15.4°
Sep
8325.5° / 10°
Oct
4916.2° / 2.5°
Nov
97.4° / -4.7°
Dec
50.4° / -10.3°
| Month | Day | Night | Rain | Wet days | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|
| January | -1.4°C | -12.4°C | 12 mm | 3.6 | 9 h 12 | 5 | Strong coverage |
| February | 1.2°C | -10.6°C | 18 mm | 3.9 | 10 h 22 | 5 | Strong coverage |
| March | 7.9°C | -5°C | 24 mm | 4.1 | 11 h 47 | 10 | Strong coverage |
| April | 15°C | 0.9°C | 49 mm | 6.3 | 13 h 23 | 40 | Strong coverage |
| May | 21.1°C | 7.3°C | 83 mm | 8.9 | 14 h 45 | 64 | Strong coverage |
| June | 26.9°C | 13.2°C | 94 mm | 8.6 | 15 h 30 | 74 | Strong coverage |
| July | 31.5°C | 16.6°C | 61 mm | 6.5 | 15 h 12 | 66 | Strong coverage |
| August | 30.5°C | 15.4°C | 49 mm | 5.6 | 14 h 01 | 73 | Strong coverage |
| September | 25.5°C | 10°C | 44 mm | 4.5 | 12 h 27 | 83 | Strong coverage |
| October | 16.2°C | 2.5°C | 43 mm | 5 | 10 h 54 | 49 | Strong coverage |
| November | 7.4°C | -4.7°C | 16 mm | 3.3 | 9 h 33 | 9 | Strong coverage |
| December | 0.4°C | -10.3°C | 16 mm | 3.5 | 8 h 52 | 5 | Strong coverage |
What has changed
Rousseau runs +0.4°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
+1.6
Feb
-0.2
Mar
+1.7
Apr
-0.9
May
-0.6
Jun
+0.4
Jul
-0.5
Aug
-0.8
Sep
+1.7
Oct
-0.6
Nov
+1.3
Dec
+1.7
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 20.0°C23 Jan 1981 | -36.1°C29 Jan 1966 | 26 mm9 Jan 1939 | 58 mm1997 · driest 0 mm in 1983 | 92 |
| February | 23.9°C29 Feb 1992 | -37.2°C9 Feb 1994 | 33 mm19 Feb 1952 | 68 mm1952 · driest 0 mm in 2002 | 93 |
| March | 31.1°C18 Mar 2012 | -28.8°C1 Mar 2014 | 57 mm14 Mar 1942 | 95 mm1977 · driest 1 mm in 1988 | 93 |
| April | 36.7°C21 Apr 1980 | -17.7°C4 Apr 2018 | 54 mm26 Apr 1964 | 162 mm1986 · driest 0 mm in 1952 | 93 |
| May | 40.6°C28 May 1934 | -6.0°C3 May 2013 | 69 mm13 May 1982 | 184 mm1982 · driest 1 mm in 1940 | 93 |
| June | 44.4°C24 Jun 1988 | 1.1°C3 Jun 1998 | 85 mm9 Jun 1971 | 211 mm2011 · driest 12 mm in 1976 | 93 |
| July | 47.2°C15 Jul 2006 | 5.6°C30 Jul 1971 | 102 mm25 Jul 1984 | 163 mm1997 · driest 3 mm in 1936 | 94 |
| August | 45.6°C15 Aug 1988 | 3.9°C12 Aug 1964 | 89 mm2 Aug 1953 | 138 mm1951 · driest 1 mm in 2001 | 93 |
| September | 42.2°C2 Sep 1983 | -6.1°C28 Sep 1951 | 70 mm2 Sep 1999 | 177 mm1996 · driest 0 mm in 2012 | 93 |
| October | 36.7°C2 Oct 1997 | -16.6°C27 Oct 2020 | 65 mm6 Oct 2007 | 145 mm2007 · driest 0 mm in 1952 | 93 |
| November | 30.6°C8 Nov 1999 | -27.8°C14 Nov 1959 | 45 mm2 Nov 1956 | 66 mm1985 · driest 0 mm in 1967 | 93 |
| December | 25.0°C1 Dec 1998 | -35.0°C30 Dec 1990 | 25 mm31 Dec 2010 | 74 mm1951 · driest 0 mm in 2001 | 93 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 30 | <1 | 5 |
| February | 0 | 0 | 27 | <1 | 4 |
| March | <1 | <1 | 25 | <1 | 3 |
| April | 3 | <1 | 13 | 2 | 2 |
| May | 9 | 2 | 2 | 3 | 0 |
| June | 21 | 9 | 0 | 3 | 0 |
| July | 29 | 20 | 0 | 2 | 0 |
| August | 27 | 18 | 0 | 1 | 0 |
| September | 17 | 8 | <1 | 1 | 0 |
| October | 4 | 1 | 10 | 1 | <1 |
| November | <1 | 0 | 25 | <1 | 3 |
| December | 0 | 0 | 31 | <1 | 4 |
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | 0% | 10% | <1% | 4% | -7.8–3.0°C |
| February | <1% | 12% | <1% | 8% | -5.1–6.7°C |
| March | 7% | 14% | 2% | 11% | 1.1–12.3°C |
| April | 26% | 21% | 5% | 22% | 12.0–18.6°C |
| May | 51% | 26% | 7% | 30% | 18.5–25.0°C |
| June | 68% | 27% | 9% | 32% | 24.4–30.3°C |
| July | 79% | 21% | 6% | 19% | 29.4–34.8°C |
| August | 81% | 18% | 5% | 14% | 28.5–33.7°C |
| September | 73% | 14% | 4% | 11% | 22.8–28.3°C |
| October | 37% | 13% | 3% | 8% | 14.0–20.1°C |
| November | 5% | 10% | <1% | 5% | 3.4–11.2°C |
| December | <1% | 11% | <1% | 7% | -4.4–4.9°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
Nearby, measured,
and named.
- Place identity
- GeoNames 5768595
- NOAA station
- USW00024025 · PIERRE RGNL AP
- Station distance
- 18.6 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 30 usable years
- Daylight
- Calculated from latitude 44.32°, 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.