Climate Chart of Helena, USA

Climate overview

Temperature

The monthly mean temperature is lowest in February, at -6.0 °C, and reaches its highest monthly mean in July, at 21.6 °C. These figures describe month-level averages, not daytime maximum temperatures, so they do not show the range visitors may experience within a day. Across calendar-month means, the unweighted mean is 6.5 °C. It is a summary of those monthly means rather than a day-weighted annual average, and it cannot by itself describe the temperature on a particular visit.

Rain

Mean daily rainfall is lowest in January, at 0.09 mm/day, while its highest monthly mean occurs in June, at 1.65 mm/day. These are daily mean amounts, not monthly totals; the lower average does not guarantee dry days or indicate how frequently rain falls. The unweighted mean across the calendar-month rainfall means is 0.67 mm/day. This offers a broad summary, but does not describe the timing or frequency of rainfall on individual days.

Sunshine

Mean daily sunshine duration is highest in July, at 13.45 hours/day, and lowest in December, at 5.36 hours/day. These averages can help with planning daylight outdoor activities, but sunshine duration is not the same as day length. The unweighted mean across the monthly sunshine means is 9.25 hours/day per day. It summarizes calendar-month averages and does not guarantee the sunshine available on a particular date.

Snow

Mean daily snowfall reaches its highest monthly mean in February, at 5.78 mm/day. This is a daily mean amount, not a monthly total, and it does not establish the number of snowy days, snow depth, snow cover, or skiing conditions. The unweighted mean across calendar-month snowfall means is 2.77 mm/day per day. This summary describes average amounts only and cannot establish how snowfall is distributed across individual days.