Portsmouth (NH) Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in Portsmouth, New Hampshire, United States of America. The numbers reflect climate data gathered over a 30-year period, from 1990 to 2020. Now, let's explore all the details to give you a full picture.

Portsmouth is known for its substantial rain/snowfall, with annual precipitation reaching 1315 mm (52 in).

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm (0.01 in))

Year-round, Portsmouth has a balanced climate with minimal variation in precipitation. The difference between the wettest month, June, with 139 mm (5.5 in), and the driest month, January, with 86 mm (3.4 in), is minimal.

June, the wettest month, has a maximum daytime temperature of 23°C (73°F). The city receives 274 hours of sunshine in this period. During the driest month January you can expect a temperature of 1°C (34°F). For more detailed insights into the city's temperatures, visit our Portsmouth Temperature page.

Portsmouth's average annual precipitation is 1315 mm (52 in). Let's compare this to some popular worldwide tourist destinations:

The city of Rome, Italy, has an average annual precipitation of 832 mm (33 in), spread fairly evenly throughout the year.

Meanwhile, Buenos Aires, Argentina, enjoys a humid subtropical climate with 1000 mm (39 in) of annual rainfall, mostly in the summer.

Melbourne, Australia, has 690 mm (27 in) of rainfall annually, spread fairly evenly throughout the year.

Singapore, situated near the equator, gets 2581 mm (102 in) of rainfall annually, with no distinct dry season and consistent monthly precipitation.

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.

The proximity of a location to a large body of water can significantly affect its rainfall patterns:

• Ocean Influence: Coastal regions typically receive more rainfall due to the presence of moisture-laden winds from the ocean. These regions tend to have more humid climates and experience more frequent precipitation, especially in winter.
• Continental Climates: Areas further from the sea, such as inland or continental regions, experience less frequent rainfall and more extreme seasonal variations in precipitation.

• "Ginger" was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.
• The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm (15 inches) wide and 20 cm (7.9 inches) thick. The snowflake fell at Fort Keogh, Montana, USA, on 28 January 1887.
• The greatest snowfall recorded was on Mt. Rainier, Washington State, USA, over 31.5 meters (103 feet) fell during the winter of 1972.

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