September
September · June · May
80climate match
United States · 1991–2020
Best time to visit
Basin.
September leads for comfortable weather in Basin: typically 25.3°C by day, 6.8°C at night, with 24 mm of rain. Based on measured 1991–2020 NOAA station history.
Best comfortSeptember
Typical high25.3°C
Typical low6.8°C
Rain in September24 mm
July
July · August · June
69climate match
May
May · September · June
85climate match
The weakest month is January, scoring 5 against September’s 80 — days reach only -0.8°C, 25° below the 24°C the score treats as ideal, and nights drop to -14.7°C.
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
5-0.8° / -14.7°
Feb
52.9° / -11.5°
Mar
2311.2° / -4.5°
Apr
4816.2° / 0.6°
May
7421.7° / 6.3°
Jun
7827.8° / 10.7°
Jul
6932.8° / 13.9°
Aug
6931.8° / 12.2°
Sep
8025.3° / 6.8°
Oct
4716.2° / 0.1°
Nov
57.1° / -6.9°
Dec
50.2° / -12.9°
| Month | Day | Night | Rain | Wet days | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|
| January | -0.8°C | -14.7°C | 6 mm | 2.1 | 9 h 11 | 5 | Strong coverage |
| February | 2.9°C | -11.5°C | 8 mm | 2.4 | 10 h 22 | 5 | Strong coverage |
| March | 11.2°C | -4.5°C | 8 mm | 2.1 | 11 h 46 | 23 | Strong coverage |
| April | 16.2°C | 0.6°C | 19 mm | 3.9 | 13 h 24 | 48 | Strong coverage |
| May | 21.7°C | 6.3°C | 35 mm | 5.8 | 14 h 45 | 74 | Strong coverage |
| June | 27.8°C | 10.7°C | 26 mm | 4.8 | 15 h 31 | 78 | Strong coverage |
| July | 32.8°C | 13.9°C | 10 mm | 2.2 | 15 h 13 | 69 | Strong coverage |
| August | 31.8°C | 12.2°C | 8 mm | 2.2 | 14 h 02 | 69 | Strong coverage |
| September | 25.3°C | 6.8°C | 24 mm | 3.6 | 12 h 27 | 80 | Strong coverage |
| October | 16.2°C | 0.1°C | 20 mm | 3.3 | 10 h 54 | 47 | Strong coverage |
| November | 7.1°C | -6.9°C | 9 mm | 2.4 | 9 h 32 | 5 | Strong coverage |
| December | 0.2°C | -12.9°C | 8 mm | 2.2 | 8 h 52 | 5 | Strong coverage |
What has changed
Basin runs +0.6°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
+2.3
Feb
-1.4
Mar
+1.4
Apr
-0.7
May
-0.5
Jun
+0.9
Jul
+0.8
Aug
+0.5
Sep
+2.2
Oct
-0.8
Nov
+0.6
Dec
+1.7
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 17.8°C31 Jan 1931 | -41.7°C30 Jan 1951 | 25 mm9 Jan 1920 | 76 mm1920 · driest 0 mm in 2018 | 116 |
| February | 22.8°C21 Feb 1982 | -46.1°C5 Feb 1899 | 23 mm7 Feb 1899 | 90 mm1899 · driest 0 mm in 1910 | 116 |
| March | 30.0°C21 Mar 2026 | -35.0°C1 Mar 1922 | 46 mm28 Mar 1924 | 132 mm1924 · driest 0 mm in 1903 | 117 |
| April | 32.2°C29 Apr 1939 | -20.0°C3 Apr 1936 | 47 mm16 Apr 1927 | 91 mm1914 · driest 0 mm in 1906 | 116 |
| May | 37.2°C30 May 1936 | -7.8°C1 May 1954 | 51 mm7 May 1988 | 93 mm2005 · driest 0 mm in 1919 | 114 |
| June | 43.3°C30 Jun 1981 | -1.1°C7 Jun 1982 | 57 mm29 Jun 1909 | 116 mm1967 · driest 0 mm in 1933 | 115 |
| July | 44.4°C12 Jul 1900 | 2.2°C31 Jul 1913 | 24 mm21 Jul 1990 | 57 mm1993 · driest 0 mm in 1959 | 113 |
| August | 46.1°C8 Aug 1983 | 1.1°C26 Aug 1992 | 36 mm11 Aug 1930 | 62 mm1930 · driest 0 mm in 1919 | 112 |
| September | 38.9°C3 Sep 1950 | -10.0°C25 Sep 1926 | 36 mm15 Sep 1994 | 86 mm2019 · driest 0 mm in 1954 | 112 |
| October | 32.8°C1 Oct 2011 | -21.7°C26 Oct 2020 | 51 mm23 Oct 1925 | 75 mm1925 · driest 0 mm in 1952 | 114 |
| November | 25.0°C1 Nov 1999 | -33.3°C16 Nov 1959 | 18 mm23 Nov 2002 | 41 mm1929 · driest 0 mm in 1930 | 114 |
| December | 19.4°C2 Dec 1995 | -41.7°C31 Dec 1978 | 37 mm15 Dec 1989 | 58 mm1989 · driest 0 mm in 1935 | 112 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 31 | 0 | 3 |
| February | 0 | 0 | 28 | <1 | 3 |
| March | <1 | 0 | 26 | <1 | 1 |
| April | 3 | <1 | 14 | <1 | <1 |
| May | 11 | 3 | 3 | 1 | <1 |
| June | 21 | 11 | 0 | <1 | 0 |
| July | 30 | 24 | 0 | <1 | 0 |
| August | 29 | 23 | 0 | 0 | 0 |
| September | 17 | 8 | 2 | <1 | <1 |
| October | 4 | <1 | 15 | <1 | <1 |
| November | 0 | 0 | 27 | <1 | 2 |
| December | 0 | 0 | 31 | 0 | 2 |
The best month has moved. On the 1961–1990 numbers the strongest month here was September (scoring 79); on 2011–2025 it is May (78). 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 | 0% | 7% | <1% | 2% | -6.5–3.9°C |
| February | <1% | 7% | <1% | 2% | -2.5–8.0°C |
| March | 8% | 8% | <1% | 2% | 6.6–14.2°C |
| April | 32% | 12% | 2% | 7% | 13.8–19.6°C |
| May | 60% | 17% | 3% | 14% | 19.4–24.7°C |
| June | 81% | 16% | 3% | 11% | 25.5–31.4°C |
| July | 91% | 8% | <1% | 3% | 31.0–35.2°C |
| August | 91% | 9% | <1% | 2% | 29.5–34.2°C |
| September | 77% | 11% | 2% | 7% | 22.8–28.3°C |
| October | 39% | 10% | 1% | 3% | 13.4–20.8°C |
| November | 3% | 7% | <1% | 2% | 3.0–11.7°C |
| December | 0% | 7% | <1% | 2% | -3.6–4.7°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 5817923
- NOAA station
- USC00480540 · BASIN
- Station distance
- 0.3 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 29 usable years
- Daylight
- Calculated from latitude 44.38°, 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.