2025 Compare Climate & Weather:
Helena, MT vs Portsmouth, NH

Highlights

On average, there are 198 sunny days per year in Portsmouth. Helena averages 189 sunny days per year. The US average is 205 sunny days.

Portsmouth, New Hampshire gets 50.1 inches of rain, on average, per year. Helena, Montana gets 12.6 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Portsmouth averages 53.2 inches of snow per year. Helena averages 42.1 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Portsmouth, New Hampshire
Summer High: the July high is around 81.9 degrees
Winter Low: the January low is 13.8
Rain: averages 50.1 inches of rain a year
Snow: averages 53.2 inches of snow a year

Helena, Montana
Summer High: the July high is around 83.4 degrees
Winter Low: the January low is 13.8
Rain: averages 12.6 inches of rain a year
Snow: averages 42.1 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Portsmouth is 6.8 (10=best), which means it is one of the most pleasant places in New Hampshire.

The annual BestPlaces Comfort Index for Helena is 6.6 (10=best), which means it is about average compared to other places in Montana.

Today's Weather - Helena, MT

50°F

Today's Weather - Portsmouth, NH

52°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Helena / Portsmouth

July is the hottest month for Helena with an average high temperature of 83.4°, which ranks it as cooler than most places in Montana. In Helena, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Helena are June, August and July.

July is the hottest month for Portsmouth with an average high temperature of 81.9°, which ranks it as warmer than most places in New Hampshire. In Portsmouth, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Portsmouth are June, August and July.

December has the coldest nighttime temperatures for Helena with an average of 13.6°. This is about average compared to other places in Montana.

January has the coldest nighttime temperatures for Portsmouth with an average of 13.8°. This is one of the warmest places in New Hampshire.

In Helena, there are 15.5 days annually when the high temperature is over 90°, which is cooler than most places in Montana.

In Portsmouth, there are 8.0 days annually when the high temperature is over 90°, which is hotter than most places in New Hampshire.

In Helena, there are 170.2 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in Montana.

In Portsmouth, there are 149.8 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in New Hampshire.

In Helena, there are 16.6 days annually when the nighttime low temperature falls below zero°, which is about average compared to other places in Montana.

In Portsmouth, there are 7.2 days annually when the nighttime low temperature falls below zero°, which is warmer than most places in New Hampshire.

June is the wettest month in Helena with 2.1 inches of rain, and the driest month is January with 0.4 inches. The wettest season is Autumn with 37% of yearly precipitation and 10% occurs in Spring, which is the driest season. The annual rainfall of 12.6 inches in Helena means that it is drier than most places in Montana.


November is the wettest month in Portsmouth with 4.8 inches of rain, and the driest month is January with 3.5 inches. The wettest season is Summer with 28% of yearly precipitation and 23% occurs in Spring, which is the driest season. The annual rainfall of 50.1 inches in Portsmouth means that it is one of the wettest places in New Hampshire.

May is the rainiest month in Helena with 11.0 days of rain, and February is the driest month with only 5.5 rainy days. There are 89.6 rainy days annually in Helena, which is about average compared to other places in Montana. The rainiest season is Summer when it rains 29% of the time and the driest is Spring with only a 21% chance of a rainy day.

May is the rainiest month in Portsmouth with 11.4 days of rain, and February is the driest month with only 7.7 rainy days. There are 118.3 rainy days annually in Portsmouth, which is one of the least rainy places in New Hampshire. The rainiest season is Summer when it rains 27% of the time and the driest is Spring with only a 23% chance of a rainy day.

An annual snowfall of 42.1 inches in Helena means that it is about average compared to other places in Montana.

An annual snowfall of 53.2 inches in Portsmouth means that it is one of the least snowy places in New Hampshire.

March is the snowiest month in Helena with 7.4 inches of snow, and 9 months of the year have significant snowfall.

January is the snowiest month in Portsmouth with 16.7 inches of snow, and 6 months of the year have significant snowfall.