Today | Weather | Monday, September 21, 2026

Weather in Napa, California

02:47 PM
Now
Cloudy Weather
70° F
Feels Like 72°
Precipitation 0 %
Wind 10 mph
UV Index (0 - 11+) 4
Humidity 67 %
Today
Cloudy Weather
Day 72°
Night 54°
Precipitation 1 %
Wind 9 mph
UV Index (0 - 11+) 5

Napa Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (September 21, 2025)
Cloudy Weather

Day

88°

Night

54°

Wind

7 mph

UV Index

50

Precipitation

0 %

Air Quality in Napa

NOW
43 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 3.2 µg/m³
PM10 11.87 µg/m³
O3 0.047 ppm
NO2 0.2 ppb
SO2 0.3 ppb
CO 0.10 ppm
NH3 0 µg/m³
NO 0.03 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.53.2 µg/m³
PM1011.87 µg/m³
O391.47 µg/m³
NO20.45 µg/m³
SO20.66 µg/m³
CO116.62 µg/m³
NH30 µg/m³
NO0.03 µg/m³