Napa receives its highest rainfall in Dec, while humidity peaks during winter months.
🌧️ Wettest:Dec — 145 mm☀️ Driest:Jul — 1 mm
💧 Humidity peaks at 84% in Jan · annual avg 66%
🌍 Climate Summary
Avg Annual Temp:61.5°F
Avg Annual Rainfall:729 mm
Avg Humidity:66%
Data Period:1981 – 2025
Napa Climate Overview
Napa has a warm temperate climate with warm summers and cold winters.
Temperatures peak in Jul and drop to their lowest in Jan,
while rainfall is highest during winter months.
Humidity remains moderate throughout the year, especially during winter months, creating cold and damp conditions.
📈 Yearly Trends
The warmest year in Napa's recorded history was 2020
(avg: 65.1°F),
while the coldest year was 1982
(avg: 58.5°F),
based on annual average temperatures.
📊 Key Climate Trends
🌡️ Napa's temperature has remained relatively stable over the past decade
📈 Minimum temperatures show a slight warming trend in recent years
🌧️ Rainfall has decreased in recent years compared to earlier periods
🌡️ Annual Temperature Trend
View Range:
Average annual high/low · Last 10 years · °F
Napa's temperatures has remained relatively stable over the past decade.
The highest recorded temperature reached
114.4°F in Sep 2022,
while the lowest dropped to
21°F in Dec 1990.
🌧️ Annual Precipitation
View Range:
Total annual precipitation · Last 10 years · mm/year
Annual rainfall in Napa shows noticeable variation. Rainfall has decreased in recent years compared to earlier periods.
Based on 45 years of data (1981–2025), Jul is typically the hottest month in Napa, California, with average high temperatures around 103.1°F.
What is the coldest month in Napa?▼
Jan is the coldest month in Napa, with average low temperatures around 29.4°F.
What is the rainiest month in Napa?▼
Dec receives the most rainfall with approximately 145 mm, while Jul is the driest with 1 mm.
What was the highest temperature ever recorded in Napa?▼
The highest recorded temperature was 114.4°F in Sep 2022. This is part of the historical record spanning 1981–2025.
What was the lowest temperature ever recorded in Napa?▼
The lowest recorded temperature was 21°F in Dec 1990.
How many years of data does this page cover?▼
This page covers 45 years of climate data from 1981 to 2025. As new data is added to the database the page automatically reflects the updated coverage.
How much sunlight does Napa get?▼
Napa receives the most sunlight in Jun with an average solar radiation of 7.99 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning, agriculture, and understanding seasonal sunshine availability in California.
Where does this weather data come from?▼
All climate data is sourced from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite and model data. It provides monthly averages for temperature, precipitation, humidity, wind speed, and solar radiation.
📚 Data Source
All weather data is sourced from NASA POWER (Prediction of Worldwide Energy Resources), a NASA project providing solar and meteorological data for renewable energy, building efficiency, and agricultural research.