Portsmouth Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in Portsmouth. The numbers are calculated over a 30-year period to provide a reliable average. Let’s explore the details in depth to provide you with a complete overview.

Generally, Portsmouth receives mid-range precipitation levels, with 973 mm annually.

Monthly Precipitation Levels

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

Portsmouth can be quite wet during October, receiving approximately 137 mm of precipitation over 19 rainy days.

In contrast March, experiences much drier conditions, with 33 mm of rainfall, spread across 15 rainy days.

October, the city’s wettest month, has a maximum daytime temperature of 29°C and receives 220 hours of sunshine. During the driest month March you can expect a temperature of 27°C. For more detailed insights into the city’s temperatures, visit our Portsmouth Temperature page.

Annual Precipitation in Dominica

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

Amsterdam Precipitation Compared World Wide

Portsmouth’s average annual precipitation is 973 mm. Let’s compare this to some popular worldwide tourist destinations:

New York City, USA, receives 1276 mm of rainfall annually, with precipitation evenly distributed throughout the year.

Osaka, Japan, experiences 1507 mm of rainfall annually, spread across the year with wetter summers.

In Brisbane, Australia, the annual precipitation is 979 mm, making it wetter than Sydney.

Ho Chi Minh City, Vietnam, receives 1955 mm of annual rainfall, with a pronounced wet season from May to November, typical of its tropical monsoon climate.

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 Warming and Precipitation

Climate change is affecting precipitation patterns worldwide, including Portsmouth:

• Changing Rainfall Patterns: Global warming causes drastic changes in the patterns of rainfall. Some areas have been experiencing increased frequency and intensity of rainfall, while other areas experience longer dry spells or even droughts.
• Local Impacts: Many regions are experiencing heavier rainfall in the winter months and drier, hotter summers. This affects agriculture, water resources, and ecosystems.

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