Helena (MT) monthly weather averages

Average daytime temperature

The bar chart below shows the average monthly peak daytime temperatures at Helena

Helena average temperature chart (Celsius) Helena average temperature chart (Fahrenheit)
Average monthly temperatures in Helena (degrees centigrade and fahrenheit)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
°C -1.3 2.2 6.1 12 17.3 22.8 27.9 27.1 20 14 5.2 -0.5
°F 29.6 35.9 43.1 53.5 63.1 73.1 82.3 80.7 67.9 57.3 41.3 31

Please note: these are the average peak daytime temperatures (usually around mid-afternoon) so do not show daytime / night highs and lows. To see the daily range of temperatures have a look at the temperature max / min chart below.

Average rainfall & rainy days

The graph below shows the average rainfall and number of rainy days per month.

Helena monthly rainfall chart (mm) Helena monthly rainfall chart (inches)
Average monthly rainfall in Helena (mm and inches)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
mm 17 12 21 28 51 55 33 34 30 19 16 16
inches 0.7 0.5 0.8 1.1 2 2.2 1.3 1.3 1.2 0.7 0.6 0.6
Rainy days 9 7 10 9 11 10 7 8 8 6 8 9

Average annual rainfall in Helena: 264.8mm (104.3 inches)

Average daily sunshine

The bar chart below shows the average daily sunshine hours in Helena

Helena average daily sunshine chart
Average daily sunshine Helena
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hrs sunshine 4.4 5.9 7.9 8.7 9.6 11 12.8 11.2 9.1 7.2 4.4 3.7

Day / night temperatures

The graph below shows the daily range of temperatures for each month.

Helena average minimum / maximum temperatures (Celsius) Helena average minimum / maximum temperatures (Fahrenheit)
Maximum and minimum daily temperatures in Helena (degrees centigrade and fahrenheit)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Min °C -12.8 -9.7 -6.3 -1.7 3.2 7.8 10.5 9.5 4.1 -0.8 -6.9 -12
Max °C -1.1 2.5 6.5 12.3 17.6 23.2 28.4 27.5 20.4 14.4 5.5 -0.3
Min °F 9.1 14.6 20.8 28.9 37.8 46 50.8 49.1 39.3 30.6 19.7 10.5
Max °F 19.6 25.5 32.2 41.5 50.7 59.9 66.9 65.3 54 44.2 30.7 21

Sea temperature

The graph below shows the average sea temperature.

Helena average sea temperature chart (Celsius) Helena average sea temperature chart (Fahrenheit)
Average sea temperature around Helena in degrees centigrade and fahrenheit
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
°C 7.7 7.6 7.8 8.2 9.2 10.8 12.8 14.3 13.7 11.7 9.7 8.3
°F 45.9 45.7 46 46.8 48.5 51.5 55 57.8 56.7 53 49.4 46.9

Wind speed

The graph below shows the average wind speed.

Helena average winspeed by month (km/h) Helena average winspeed by month (mph)
Average wind speed in Helena (mph and kmh)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
km/h 14 14 16 17 16 15 14 13 14 14 14 14
mph 9 9 10 11 10 9 9 8 9 9 9 9

A monthly average windspeed of over 16km/h or 10mph suggests a location is fairly windy.

Relative humidity

The graph below shows the average relative humidity.

Helena relative humidity averages
Average relative humidity in Helena
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
67% 65% 61% 54% 55% 53% 47% 48% 55% 58% 66% 69%