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Sunnyvale, CA Weather on September 4
September 4th in Sunnyvale, CA typically brings pleasant fall weather, with average highs around 79°F and lows near 59°F. Over 55 years of records, the warmest September 4th was in 2004 (80°F average), while the coldest was 2000 (62°F) — a 18°F range across recorded history. This date has historically been dry, with little recorded precipitation. The last decade has been 3.0°F warmer on this date compared to 20-30 years ago.
What to Expect on September 4
Planning for September 4th in Sunnyvale, CA? Great weather for outdoor activities.
September 4 Weather Records for Sunnyvale
- •The all-time record high for September 4th in Sunnyvale, CA is 97°F, set in 2022.
- •The coldest September 4th on record dropped to 51°F in 2000.
- •Temperatures have reached 90°F or higher on September 4th in 6 of the last 55 years.
- •Last year (1971), September 4th was 8°F warmer than the long-term average.
Frequently Asked Questions
What was the warmest September 4 ever in Sunnyvale?
The warmest September 4 in Sunnyvale, CA reached 97°F in 2022. That is 18°F above the long-term average high of 79°F.
What was the coldest September 4 ever in Sunnyvale?
The coldest September 4 in Sunnyvale, CA dropped to 51°F in 2000. That is 8°F below the long-term average low of 59°F.
What is the average temperature on September 4 in Sunnyvale?
On September 4, Sunnyvale averages a high of 79°F and a low of 59°F based on 55 years of NOAA weather observations from MOFFETT FED AIRFIELD.
How many years of weather data are available for September 4 in Sunnyvale?
We have 55 years of weather records for September 4 in Sunnyvale, CA, sourced from NOAA's Global Historical Climatology Network. Records include daily high and low temperatures, precipitation, and snowfall data going back to 2025.
September 4 Weather History in Sunnyvale
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 72°F | 63°F | -- | -- |
| 2024 | 90°F | 64°F | 0" | -- |
| 2023 | 79°F | 61°F | 0" | -- |
| 2022 | 97°F | 62°F | 0" | -- |
| 2021 | 84°F | 56°F | 0" | -- |
| 2020 | 82°F | 59°F | 0" | -- |
| 2019 | 83°F | 61°F | 0" | -- |
| 2018 | 75°F | 60°F | 0" | -- |
| 2017 | 85°F | 70°F | 0" | -- |
| 2016 | 75°F | 54°F | 0" | -- |
| 2015 | 77°F | 53°F | 0" | -- |
| 2014 | 78°F | 62°F | 0" | -- |
| 2013 | 79°F | 60°F | 0" | -- |
| 2012 | 73°F | 57°F | 0" | -- |
| 2011 | 71°F | 60°F | 0" | -- |
| 2010 | 71°F | 59°F | 0" | -- |
| 2009 | 73°F | 58°F | 0" | -- |
| 2008 | 96°F | 60°F | 0" | -- |
| 2007 | 78°F | 62°F | 0" | -- |
| 2006 | 70°F | 57°F | 0" | -- |
| 2005 | 72°F | 56°F | 0" | -- |
| 2004 | 95°F | 64°F | 0" | -- |
| 2003 | 74°F | 61°F | 0" | -- |
| 2002 | 74°F | 58°F | 0" | -- |
| 2001 | 76°F | 58°F | 0" | -- |
| 2000 | 73°F | 51°F | 0" | -- |
| 1999 | 73°F | 55°F | 0" | -- |
| 1998 | 79°F | 63°F | 0" | -- |
| 1997 | 93°F | 64°F | 0" | -- |
| 1996 | 76°F | 54°F | 0" | -- |
| 1995 | 78°F | 54°F | 0" | -- |
| 1994 | 90°F | 56°F | 0" | -- |
| 1993 | 74°F | 60°F | 0" | -- |
| 1992 | 80°F | 60°F | 0" | -- |
| 1991 | 76°F | 63°F | 0" | -- |
| 1990 | 77°F | 60°F | 0" | -- |
| 1989 | 77°F | 58°F | 0" | -- |
| 1988 | 85°F | 60°F | 0" | -- |
| 1987 | 73°F | 61°F | 0" | -- |
| 1986 | 73°F | 61°F | 0" | -- |
| 1985 | 79°F | 58°F | 0" | -- |
| 1984 | 88°F | 60°F | 0" | -- |
| 1983 | 89°F | 64°F | 0" | -- |
| 1982 | 83°F | 57°F | 0" | -- |
| 1981 | 72°F | 55°F | 0" | -- |
| 1980 | 71°F | 59°F | 0" | -- |
| 1979 | 81°F | 59°F | 0" | -- |
| 1978 | 81°F | 65°F | 0" | -- |
| 1977 | 83°F | 59°F | 0" | -- |
| 1976 | 73°F | 61°F | 0" | -- |
| 1975 | 84°F | 58°F | 0" | -- |
| 1974 | 76°F | 58°F | 0" | -- |
| 1973 | 71°F | 58°F | 0" | -- |
| 1972 | 75°F | 62°F | 0" | -- |
| 1971 | 87°F | 57°F | 0" | -- |
Based on 55 years of data from NOAA station: MOFFETT FED AIRFIELD
Monthly Climate Averages
Historical temperature and precipitation averages for Sunnyvale, CA, based on 55+ years of weather data.
Temperatures in Fahrenheit. Precipitation and snowfall in inches.