Napa (CA) Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in Napa (CA). The numbers are calculated over a 30-year period to provide a reliable average. Now, let’s break down all the details for a clearer picture.

On average, Napa receives a reasonable amount of rainfall, with an annual precipitation of 585 mm.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm)

Significant seasonal changes in precipitation occur throughout the year. During the wet season, December receives substantial rainfall, averaging 120 mm of precipitation, recorded across 11 rainy days.

In contrast, the drier season, July brings less rainfall, with 0.1 mm over 0 rainy days.

December, the city’s wettest month, has a maximum daytime temperature of 14°C and receives 160 hours of sunshine. During the driest month July you can expect a temperature of 29°C. For more detailed insights into the city’s temperatures, visit our Napa Temperature page.

Annual Precipitation in the United States of America

The map below shows the annual precipitation across the United States of America. You can also select the different months in case you are interested in a specific month.

Amsterdam Precipitation Compared World Wide

Napa’s average annual precipitation is 585 mm. Let’s compare this to some popular worldwide tourist destinations:

Boston, USA, experiences 1238 mm of annual precipitation, including significant snowfall during the winter.

In Seoul, South Korea, the average annual precipitation is 1237 mm, with most rain falling during the summer monsoon season.

Perth, Australia, receives 565 mm of rainfall annually, mostly during the winter months.

Kuala Lumpur, Malaysia, receives 2529 mm of annual rainfall, characteristic of its equatorial tropical rainforest climate, with consistent rainfall throughout the year and peak months during March and November.

How is Precipitation Measured?

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

Global Precipitation Patterns

Tropical Rainforests: In tropical regions, rainfall is generally abundant year-round. Areas near the equator, like the Amazon rainforest, can receive up to 3000 mm of rain annually.

Desert Regions: Deserts such as the Sahara and Arabian deserts typically see less than 250 mm of rainfall annually. Rainfall tends to be infrequent, but when it does occur, it is often intense.

Temperate Zones: In temperate regions, precipitation tends to be more evenly distributed, though areas closer to the ocean may see more rain in the winter months, and areas further inland experience drier summers.

Polar Regions: Precipitation in polar regions, like Antarctica, is extremely low, often falling as snow. Average annual precipitation in Antarctica is less than 200 mm, with some areas receiving as little as 50 mm annually.

For more detailed information about Napa (CA)’s weather, including sunshine hours, humidity levels, and temperature data, visit our Napa (CA) Climate page.