Warm
Average highs sit around 27°C, giving warm days by monthly-average standards.
September verdict
Napa, California, United States in September
Weather score66Good
Good for holiday weather
Average highs sit around 27°C, giving warm days by monthly-average standards. Sunshine averages 9.4h per day, so bright days are a strong part of the month. Rainfall averages 9mm, which is relatively low for holiday planning.
September weather
Monthly averages
Temp
27°C
Rain
9mm
Sun
9.4h
Sea
13°C
Weather score
66
Good
Seasonal climate calendar
TemperatureTemp
RainRain
SunSun
SwimSwim
Weather scoreWeather score
Trip feel
Drier
Rainfall averages 9mm, which is relatively low for holiday planning.
Bright
Sunshine averages 9.4h per day, so bright days are a strong part of the month.
Cool sea
Sea temperatures average 13°C, so the water can feel cool.
Map
Weather map
Compare Napa, California, United States with nearby places by weather score, rain, sun, temperature, and swim conditions.
Temperature
September27°C average high
September is one of Napa's warmest months, with daytime heat above the yearly average.
Warmest monthsJune to September
This stretch sets the upper range for average daytime heat.
Rain
September9mm average rain
September is one of Napa's driest months, making outdoor days easier to plan than in wetter parts of the year.
Driest monthsApril to October
This is the drier part of the year, when outdoor plans usually need less weather flexibility.
Sun
September9.4 hours average sun
September is brighter than Napa's yearly average, though the strongest sunshine usually sits closer to the peak months.
Brightest monthsApril to August
This stretch has the strongest sunshine in the monthly averages.
Sea temperature
September13°C average sea
September is one of Napa's warmest sea months, when swimming comfort is usually strongest.
Warmest seaJanuary and August to December
Sea temperatures are usually near 12°C in this stretch, so swimming comfort is at its strongest.
Weather score
September66 weather score
September is one of Napa's best weather-score months, combining the strongest overall balance in the yearly averages.
Best weather monthsMay to September
These months have the strongest weather score in the monthly averages.
