September
September · July · August
82climate match
United States · 1991–2020
Best time to visit
Mount Idaho.
September leads for comfortable weather in Mount Idaho: typically 23.2°C by day, 7.3°C at night, with 34 mm of rain. Based on measured 1991–2020 NOAA station history.
Best comfortSeptember
Typical high23.2°C
Typical low7.3°C
Rain in September34 mm
July
July · August · September
70climate match
September
September · June · August
84climate match
The weakest month is January, scoring 5 against September’s 82 — days reach only 3.5°C, 20° 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
53.5° / -4.3°
Feb
55.6° / -3.7°
Mar
159.9° / -1.3°
Apr
2613.3° / 1.2°
May
4717.9° / 5°
Jun
6721.4° / 8.2°
Jul
8127.8° / 11.9°
Aug
7928.2° / 11.1°
Sep
8223.2° / 7.3°
Oct
4014.4° / 2.2°
Nov
67.1° / -1.8°
Dec
52.8° / -4.8°
| Month | Day | Night | Rain | Wet days | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|
| January | 3.5°C | -4.3°C | 32 mm | 7 | 9 h 01 | 5 | Good coverage |
| February | 5.6°C | -3.7°C | 33 mm | 6.8 | 10 h 17 | 5 | Good coverage |
| March | 9.9°C | -1.3°C | 58 mm | 9.3 | 11 h 45 | 15 | Good coverage |
| April | 13.3°C | 1.2°C | 77 mm | 11.4 | 13 h 28 | 26 | Good coverage |
| May | 17.9°C | 5°C | 89 mm | 11.5 | 14 h 55 | 47 | Good coverage |
| June | 21.4°C | 8.2°C | 79 mm | 10 | 15 h 43 | 67 | Good coverage |
| July | 27.8°C | 11.9°C | 33 mm | 4.4 | 15 h 24 | 81 | Good coverage |
| August | 28.2°C | 11.1°C | 25 mm | 3.6 | 14 h 08 | 79 | Good coverage |
| September | 23.2°C | 7.3°C | 34 mm | 4.5 | 12 h 29 | 82 | Good coverage |
| October | 14.4°C | 2.2°C | 47 mm | 7.6 | 10 h 50 | 40 | Good coverage |
| November | 7.1°C | -1.8°C | 48 mm | 9.5 | 9 h 23 | 6 | Good coverage |
| December | 2.8°C | -4.8°C | 36 mm | 7.9 | 8 h 40 | 5 | Good coverage |
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 16.7°C31 Jan 1971 | -31.1°C7 Jan 1937 | 31 mm23 Jan 1970 | 124 mm1894 · driest 6 mm in 1961 | 97 |
| February | 20.6°C24 Feb 1986 | -31.1°C9 Feb 1933 | 41 mm7 Feb 1938 | 142 mm1904 · driest 2 mm in 1967 | 97 |
| March | 25.6°C29 Mar 1978 | -22.8°C5 Mar 1955 | 29 mm16 Mar 2012 | 124 mm2012 · driest 0 mm in 1902 | 97 |
| April | 31.1°C24 Apr 1977 | -11.7°C1 Apr 1936 | 49 mm28 Apr 1895 | 142 mm1997 · driest 12 mm in 1973 | 96 |
| May | 35.6°C25 May 1928 | -7.2°C1 May 1954 | 45 mm22 May 1948 | 209 mm1957 · driest 22 mm in 1928 | 97 |
| June | 36.7°C29 Jun 1939 | -2.8°C17 Jun 1942 | 49 mm5 Jun 1964 | 195 mm1964 · driest 0 mm in 2000 | 96 |
| July | 42.2°C27 Jul 1934 | 0.6°C2 Jul 1955 | 54 mm9 Jul 1997 | 130 mm1997 · driest 0 mm in 1953 | 95 |
| August | 41.1°C4 Aug 1961 | -1.7°C24 Aug 1992 | 41 mm25 Aug 1903 | 106 mm1965 · driest 0 mm in 1969 | 92 |
| September | 40.0°C3 Sep 1950 | -7.2°C20 Sep 1983 | 77 mm14 Sep 1955 | 133 mm1985 · driest 0 mm in 2012 | 93 |
| October | 30.6°C2 Oct 1963 | -17.8°C29 Oct 1971 | 52 mm10 Oct 1955 | 140 mm1893 · driest 0 mm in 1987 | 93 |
| November | 22.2°C13 Nov 1999 | -27.2°C15 Nov 1955 | 38 mm3 Nov 1905 | 147 mm1927 · driest 4 mm in 1969 | 97 |
| December | 18.9°C5 Dec 1939 | -31.7°C30 Dec 1968 | 28 mm21 Dec 1955 | 113 mm1996 · driest 7 mm in 1976 | 97 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 25 | <1 | 3 |
| February | 0 | 0 | 24 | <1 | 2 |
| March | 0 | 0 | 21 | 2 | 3 |
| April | <1 | 0 | 13 | 3 | 1 |
| May | 4 | <1 | 3 | 3 | <1 |
| June | 8 | 1 | <1 | 2 | 0 |
| July | 24 | 12 | 0 | <1 | 0 |
| August | 25 | 12 | <1 | <1 | 0 |
| September | 13 | 4 | <1 | 1 | 0 |
| October | 1 | <1 | 10 | 1 | <1 |
| November | 0 | 0 | 20 | 1 | 2 |
| December | 0 | 0 | 26 | <1 | 4 |
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | 0% | 27% | 3% | 29% | 0.1–5.7°C |
| February | <1% | 24% | 3% | 26% | 2.2–8.6°C |
| March | 2% | 33% | 5% | 41% | 6.2–11.6°C |
| April | 13% | 34% | 8% | 45% | 10.6–16.1°C |
| May | 33% | 35% | 9% | 45% | 15.0–20.9°C |
| June | 54% | 31% | 9% | 37% | 19.1–24.2°C |
| July | 85% | 13% | 3% | 8% | 25.4–30.3°C |
| August | 86% | 12% | 3% | 9% | 24.9–30.6°C |
| September | 62% | 18% | 5% | 19% | 18.7–25.4°C |
| October | 19% | 24% | 5% | 29% | 12.2–17.5°C |
| November | <1% | 30% | 4% | 37% | 4.5–10.0°C |
| December | 0% | 26% | 3% | 28% | 1.0–5.8°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 5601602
- NOAA station
- USC00103771 · GRANGEVILLE
- Station distance
- 4.1 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 21 usable years
- Daylight
- Calculated from latitude 45.90°, 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.