Napa Cnty Arpt climate by month
Averages and records for each calendar month at Napa Cnty Arpt, United States, from 1998 to 2026. The warmest month is September, averaging 26.9°C; the coolest is December at 14.1°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 14.3°C | 3.0°C | 26.7°C12 January 2009 | −7.8°C15 January 2007 | 28 / 28 |
| February | 16.2°C | 3.6°C | 27.2°C5 February 2011 | −6.0°C20 February 2018 | 28 / 28 |
| March | 18.0°C | 4.8°C | 30.6°C22 March 2022 | −2.8°C10 March 2009 | 28 / 28 |
| April | 20.0°C | 5.8°C | 32.8°C26 April 2004 | −3.9°C24 April 2008 | 28 / 28 |
| May | 22.8°C | 8.2°C | 38.3°C15 May 2008 | −0.6°C23 May 2010 | 28 / 29 |
| June | 25.6°C | 10.7°C | 43.3°C14 June 2000 | 2.2°C8 June 1999 | 29 / 29 |
| July | 25.8°C | 12.1°C | 41.1°C22 July 2006 | 6.1°C1 July 2007 | 29 / 29 |
| August | 26.3°C | 12.1°C | 41.1°C14 August 2020 | 5.6°C31 August 2008 | 29 / 29 |
| September | 26.9°C | 10.4°C | 46.1°C6 September 2022 | 1.7°C29 September 2019 | 28 / 29 |
| October | 24.0°C | 7.5°C | 38.3°C15 October 2020 | −1.1°C31 October 2002 | 28 / 28 |
| November | 18.2°C | 4.3°C | 29.4°C14 November 2010 | −5.6°C12 November 2000 | 28 / 28 |
| December | 14.1°C | 2.9°C | 25.6°C19 December 1999 | −8.8°C5 December 2013 | 28 / 28 |
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 28 to 29 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.