The Average Rainfall for Montana

Average rainfall statistics vary widely over Montana.

The average rainfall for Montana varies widely across the state due to the influence of the various topographical features, including mountains, plains, glaciers, hills and valleys.

Topography

Average rainfall is the highest in the areas next to Montana's western mountain ranges, except where the tallest peaks block rain clouds to produce a "rain shadow" effect. On average, western Montana is the wettest, with the north central part of the state the driest.

Extremes

Nearly half the average rainfall for Montana falls from May to July. The highest state average is at Many Glacier with 40.85 inches recorded. The driest is in Belfry, Carbon County, with the lowest annual average of 6.85 inches. The state record was 1953 with 55.51 inches.

August 2010

According to the NOAA's National Weather Service records from August, 2010, Montana had the 14th wettest summer ever with 6.88 inches of rain. The 18-city mean monthly precipitation average for August was 1.92 inches, the 16th wettest since 1880. Average daily rain records for the month were set in Billings, with .93 inch, Helena, with .88 inch and Butte, with .51 inch.

References

• NOAA National Weather Service: Montana Weather/Precipitation Summary
• Cool Weather: Montana Annual Rainfall
• Western Regional Climate Center: Climate of Montana