Mount Wilson climate by month
Averages and records for each calendar month at Mount Wilson, United States, from 1948 to 2026. The warmest month is July, averaging 27.8°C; the coolest is January at 11.7°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 11.7°C | 2.7°C | 25.0°C31 January 2003 | −12.8°C29 January 1969 | 66 / 69 |
| February | 12.1°C | 2.7°C | 26.7°C14 February 1985 | −11.7°C27 February 1962 | 60 / 68 |
| March | 13.1°C | 3.1°C | 28.3°C16 March 2007 | −10.0°C3 March 1966 | 65 / 69 |
| April | 15.6°C | 4.9°C | 30.0°C6 April 1989 | −7.8°C21 April 1963 | 64 / 68 |
| May | 19.5°C | 8.7°C | 33.3°C22 May 2000 | −5.6°C5 May 1964 | 62 / 70 |
| June | 24.4°C | 13.5°C | 38.3°C30 June 2013 | −1.7°C7 June 1950 | 66 / 66 |
| July | 27.8°C | 17.6°C | 38.9°C5 July 2007 | 3.3°C11 July 1974 | 67 / 71 |
| August | 27.6°C | 17.2°C | 38.3°C24 August 2010 | 2.8°C20 August 1959 | 67 / 70 |
| September | 25.5°C | 14.8°C | 36.7°C2 September 1950 | 1.1°C25 September 1948 | 68 / 68 |
| October | 20.7°C | 10.5°C | 35.0°C2 October 2024 | −7.8°C29 October 1971 | 67 / 69 |
| November | 15.6°C | 6.0°C | 28.9°C3 November 2010 | −9.4°C29 November 1975 | 67 / 70 |
| December | 12.0°C | 3.1°C | 25.6°C3 December 1958 | −12.2°C14 December 1967 | 62 / 69 |
Years shows the number behind the average high, then the number holding a record for that month. They differ because a year contributes an average only when the month has at least 25 days of readings, while a single reading is enough to set a record. The average low is withheld on the same 25-day rule and is counted separately again; it is shown as a dash where the archive cannot support it. Across the twelve months here the averages rest on 60 to 68 years each.
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Every figure on this page is computed from NOAA GHCN-Daily observations stored per station, per year, per month. Nothing is modelled, interpolated or estimated, and a month the archive never covered is left out rather than filled in. A station appears here only once all twelve months carry an average from at least 10 years. See how this is built.