Climate Insights for Helena

The climate in Helena is warm and mild. The average annual temperature is 18°C and approximately 1516mm of precipitation falls per year. Helena receives a notable amount of rainfall throughout the year, including during its driest month. Helena is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: July, August, June. The coldest months are January, December, February, when temperatures can drop to 3°C.

Temperatures in Helena vary considerably across the year, with a 29°C difference between the coldest and warmest months. The warmest month is July, when average highs reach 32°C and the mean temperature sits around 28°C. January is the coolest month, with minimum temperatures around 3°C and an average of 7°C. On average, daily temperatures fluctuate by about 10°C between overnight lows and afternoon highs. The sharpest temperature change occurs between October and November, with a 7°C shift in average temperatures.

Helena is a fairly wet location, receiving approximately 1516mm of precipitation annually, which averages out to around 126mm per month. The wettest month is February, averaging 194mm of rainfall. March and December also tend to see above-average precipitation. The driest month is September, with just 70mm. That's 123mm less than February, the wettest month. Precipitation varies noticeably between seasons, with the first half (January to June) of the year generally seeing more rainfall.

Helena is relatively calm, with an average annual wind speed of 3km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is March, averaging 4km/h, though still comfortable for most outdoor activities. The calmest conditions occur in August, with average winds dropping to 2km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 2km/h gap between the calmest and windiest months.

It is currently spring in Helena, which began on March 20, 2026. Helena is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in July at around 32°C, while the coldest stretch bottoms out in January near 3°C. Summer is next, beginning on June 21, 2026 — 4 days from now.

The best time to visit Helena is during October, when the weather is most comfortable for travellers. During these months, average temperatures hover around 19°C with modest rainfall averaging 98mm per month. By contrast, July can be uncomfortably hot with highs reaching 32°C, while January is the coldest period with lows dropping to 3°C. Despite being the best months overall, some rain is still likely — pack a waterproof layer and plan a mix of indoor and outdoor activities.

The table below shows monthly climate averages for Helena based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.