Napa County Weather in August
Average highs run from 89°F on August 1 to 89°F on August 31, and lows from 56°F to 55°F. Normal precipitation for the month is 0.04 in over about 0 wet days.
August day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
August at a glance
- Average high
- 89°F
- Average low
- 56°F
- Precipitation
- 0.04 in
- Record high
- 106°FAug 14, 2020
- Record low
- 42°FAug 31, 2008
- Chance of a freeze
- 0%
- Days of 90°F or more
- 13.2
- Daylight
- 14 h 08 min to 13 h 02 min
- Cloud cover
- 26%
- Humidity
- 48%
- Dew point
- 46°F
- Wind
- 6.7 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation.
| Date | Normal high | Normal low | Record high | Record low | Chance wet |
|---|---|---|---|---|---|
| Aug 1 | 89°F | 56°F | 92°F 2000 | 48°F 2008 | 0% |
| Aug 2 | 89°F | 56°F | 95°F 1998 | 45°F 2013 | 0% |
| Aug 3 | 89°F | 56°F | 101°F 1998 | 50°F 2007 | 0% |
| Aug 4 | 89°F | 56°F | 95°F 1998 | 46°F 2007 | 0% |
| Aug 5 | 89°F | 56°F | 86°F 2005 | 46°F 2002 | 0% |
| Aug 6 | 89°F | 56°F | 91°F 2023 | 44°F 2002 | 0% |
| Aug 7 | 89°F | 56°F | 90°F 2002 | 46°F 2003 | 0% |
| Aug 8 | 89°F | 56°F | 97°F 2002 | 45°F 2002 | 0% |
| Aug 9 | 89°F | 56°F | 100°F 2002 | 49°F 2009 | 0% |
| Aug 10 | 89°F | 56°F | 93°F 2002 | 47°F 2003 | 0% |
| Aug 11 | 89°F | 56°F | 92°F 1998 | 45°F 2003 | 0% |
| Aug 12 | 89°F | 56°F | 91°F 1998 | 47°F 2003 | 0% |
| Aug 13 | 89°F | 56°F | 94°F 2020 | 43°F 2007 | 0% |
| Aug 14 | 89°F | 56°F | 106°F 2020 | 47°F 2001 | 0% |
| Aug 15 | 89°F | 56°F | 102°F 2020 | 47°F 2000 | 0% |
| Aug 16 | 89°F | 56°F | 101°F 2015 | 46°F 2014 | 0% |
| Aug 17 | 89°F | 56°F | 94°F 2020 | 45°F 2007 | 0% |
| Aug 18 | 89°F | 56°F | 94°F 2020 | 46°F 2007 | 1% |
| Aug 19 | 89°F | 56°F | 84°F 2013 | 48°F 1999 | 1% |
| Aug 20 | 89°F | 56°F | 95°F 2023 | 46°F 2000 | 1% |
| Aug 21 | 89°F | 56°F | 93°F 2020 | 47°F 2001 | 1% |
| Aug 22 | 89°F | 56°F | 97°F 1999 | 45°F 2006 | 1% |
| Aug 23 | 89°F | 56°F | 96°F 2010 | 45°F 2005 | 1% |
| Aug 24 | 89°F | 56°F | 104°F 2010 | 47°F 2005 | 1% |
| Aug 25 | 89°F | 55°F | 98°F 1999 | 47°F 2000 | 1% |
| Aug 26 | 89°F | 55°F | 98°F 2017 | 45°F 2005 | 1% |
| Aug 27 | 89°F | 55°F | 98°F 2004 | 44°F 2005 | 1% |
| Aug 28 | 89°F | 55°F | 100°F 2008 | 45°F 2005 | 1% |
| Aug 29 | 89°F | 55°F | 99°F 2007 | 46°F 2005 | 1% |
| Aug 30 | 89°F | 55°F | 96°F 2023 | 44°F 2010 | 1% |
| Aug 31 | 89°F | 55°F | 97°F 2017 | 42°F 2008 | 1% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PDT).
- August 1
- sunrise 6:11 AM, sunset 8:19 PM
- August 31
- sunrise 6:38 AM, sunset 7:40 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00047643 (Saint Helena), public domain. Records: NOAA GHCN-Daily, station USW00093227, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.