Temperatures in September
It's warm in September in Napa with an average temperature of 28°C. Temperatures this month range from a low of 24°C to a high of 31°C. At night, you can expect temperatures between 10°C and 14°C.
Max and Min Temperatures per Day
This chart shows the daily maximum and minimum temperatures in degrees Celsius for Napa in September. The red line indicates the max temperatures, and the blue line shows the minimums.
Start of September
The month of September starts in Napa with hot temperatures, averaging around 29°C during the day and nights close to 14°C. You won’t see any precipitation in the first days of the month, it’s all sunny skies.
Since temperatures can differ between day and night, it’s a good idea to dress in layers.
Mid-September
By mid-September, the average daytime temperature drops to around 27°C, with nights close to 13°C. No precipitation expected during this period, so you can enjoy plenty of sunshine.
End of September
By the end of September, the average daytime temperature in Napa will be around 28°C, with nights close to 12°C. No precipitation expected, with plenty of sunshine on the horizon.
Precipitation in September
According to weather history, there is only 3,1 mm of precipitation in September. The wind speed is around 4 Bft, mostly coming from the Southwest.
The average chance of precipitation is only 3% in September.
Precipitation Chance
This chart shows the daily precipitation chance (in percentages) in September for Napa. 0% means it never rained on that day in the past 10 years, and 100% means it rained every day. All values in between represent the average chance of precipitation on that day.
Napa in September |
London | ||
|---|---|---|---|
 Average Temperature |
28°C | 20°C | |
 High Temp |
31°C | 22°C | |
| Low Temp |
24°C | 17°C | |
 Total Precipitation |
3,1 mm | 44 mm | |
| Rainy Days |
1 day | 8 days | |
August
UV index
The UV index is a maximum of 8 this month. That's a very high value on the intensity scale of 1 to 11. Unprotected skin can burn within 10-15 minutes.
Is September a good time to visit Napa?
Want nice weather? Then September is a great time to be in Napa. You’ll have pleasant temperatures and not too much rain this month.
Temperature records for Napa in September
With 44°C, Napa hit the highest temperature in the last 10 years in September 2022. The lowest daytime temperature in this month was 18°C in 2020. The extreme night temperatures ranged from a low of 4°C to a high of 22°C.
Check out the climate of Napa for all months and discover the best travel time
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Daily Temperature in September in Napa
This chart shows the average daily temperatures, both day and night, for each day in September in Napa, measured in degrees Celsius. The red line represents the maximum temperatures, while the blue line shows the minimums. The days of the month are displayed at the bottom of the chart. The data, based on historical observations, gives an overview of the average daily temperatures during this month.
Daily Precipitation in September in Napa
The chart below shows the average daily precipitation in September for Napa, measured in millimetres over the past years. Precipitation is always measured as water, even if it’s snow or hail. The days of the month are shown at the bottom of the chart.
A low average precipitation means that the chance of rain on that day is usually small, while a higher average suggests that rain is more likely. But it’s still an average, so each day can be different. Based on historical weather data for September, you can expect about 1 day of rain in Napa.
Daily UV Index in September in Napa
This chart shows the average daily UV index in September in Napa, with the UV index ranging from 0 to a maximum of 11. The bottom of the chart shows the days of the month. Based on historical data, this chart provides an idea of the daily UV radiation levels you can expect.
Temperature in September in Napa Over the Years
This chart shows the average temperature in September in Napa, measured in degrees Celsius, over the past years.
Total Precipitation in September in Napa Over the Years
This chart shows the average precipitation in September in Napa, measured in millimetres over the past years. Precipitation is always measured as water, even if it’s snow or hail.
Daily climate in September for Napa
Click on a specific day in September for detailed info on the typical weather on that day in Napa. Check out the historical temperatures and precipitation over the past 10 years on this day.
Weather experiences in September in Napa
Have you been to Napa in September?
Share your weather experience in September in Napa.
Average Weather in Napa by Month
Click on a month below to see detailed weather info for Napa. Based on historical weather data, you can see the average temperature, precipitation, wind, and UV index for each day of the month.
