Great Falls (MT) Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in Great Falls, Montana, United States of America. These averages rely on historical data collected over 30 years, from 1990 to 2020. Now, let's break down all the details for a clearer picture.

Great Falls typically sees modest rain/snowfall throughout the year, with an average annual precipitation of 387 mm (15 in). The city experiences a distinct dry season during certain months, as illustrated in the graph below.

Monthly Precipitation Levels

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

The climate in Great Falls shows significant variation throughout the year. Expect 67 mm (2.6 in) of precipitation during the wettest month May, distributed over 12 rainy days.

In contrast, March offers drier and sunnier days, with around 15 mm (0.6 in) of snow/rainfall over 7 snowy/rainy days.

May, the wettest month, has a maximum daytime temperature of 18°C (64°F). The city receives 289 hours of sunshine in this period. During the driest month March you can expect a temperature of 9°C (48°F). For more detailed insights into the city's temperatures, visit our Great Falls Temperature page.

Great Falls's average annual precipitation is 387 mm (15 in). Let's compare this to some popular worldwide tourist destinations:

Boston, USA, experiences 1238 mm (49 in) of annual precipitation, including significant snowfall during the winter.

Osaka, Japan, experiences 1507 mm (59 in) of rainfall annually, spread across the year with wetter summers.

In Tokyo, Japan, the average annual precipitation is 1528 mm (60 in), with significant summer rains due to typhoon season.

Ho Chi Minh City, Vietnam, receives 1955 mm (77 in) of annual rainfall, with a pronounced wet season from May to November, typical of its tropical monsoon climate.

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.

Climate change is affecting precipitation patterns worldwide, including Great Falls (MT):

• 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.

• "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 Great Falls (MT)'s weather, including sunshine hours, humidity levels, and temperature data, visit our Great Falls (MT) Climate page.