Boulder (CO) monthly weather averages

Contents

Average daytime temperature

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

Boulder average temperature chart (Celsius) Boulder average temperature chart (Fahrenheit)
Average monthly temperatures in Boulder (degrees centigrade and fahrenheit)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
°C 5.5 7.5 10.2 15.3 20.4 25.7 29.2 27.8 23.1 17.8 10.1 6.3
°F 41.9 45.5 50.4 59.5 68.7 78.2 84.5 82.1 73.6 64.1 50.2 43.3

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.

Boulder monthly rainfall chart (mm) Boulder monthly rainfall chart (inches)
Average monthly rainfall in Boulder (mm and inches)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
mm 17 19 41 55 78 51 47 36 40 31 31 19
inches 0.6 0.7 1.6 2.2 3.1 2 1.8 1.4 1.6 1.2 1.2 0.7
Rainy days 6 6 9 8 10 9 9 9 7 5 6 6

Average annual rainfall in Boulder: 397.633mm (156.5 inches)

Average daily sunshine

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

Boulder average daily sunshine chart
Average daily sunshine Boulder
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hrs sunshine 7.4 8.1 8.8 9.8 10.1 11.1 11.1 10.5 9.6 8.6 7 6.9

Day / night temperatures

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

Boulder average minimum / maximum temperatures (Celsius) Boulder average minimum / maximum temperatures (Fahrenheit)
Maximum and minimum daily temperatures in Boulder (degrees centigrade and fahrenheit)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Min °C -8.9 -6.7 -4.2 0.4 5.5 9.8 13.1 12 7.5 2.2 -3.7 -7.4
Max °C 5.9 7.9 10.6 15.7 20.8 26.1 29.6 28.2 23.5 18.2 10.5 6.6
Min °F 16.1 20 24.4 32.6 41.8 49.6 55.5 53.6 45.5 36 25.4 18.7
Max °F 29.3 33.1 37.8 46.4 55.6 64.2 70.3 68.2 59.9 50.4 38.1 31.3

Sea temperature

The graph below shows the average sea temperature.

Boulder average sea temperature chart (Celsius) Boulder average sea temperature chart (Fahrenheit)
Average sea temperature around Boulder in degrees centigrade and fahrenheit
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
°C 10.4 10.2 10.5 11.2 12.6 14.4 16.6 18.4 17.6 15.3 13 11.3
°F 50.8 50.4 50.9 52.2 54.6 58 61.9 65.1 63.7 59.5 55.4 52.4

Wind speed

The graph below shows the average wind speed.

Boulder average winspeed by month (km/h) Boulder average winspeed by month (mph)
Average wind speed in Boulder (mph and kmh)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
km/h 17 17 18 18 17 16 15 15 15 15 16 17
mph 11 11 11 11 11 10 9 9 9 9 10 10

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.

Boulder relative humidity averages
Average relative humidity in Boulder
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
55% 56% 54% 50% 51% 48% 47% 48% 49% 49% 55% 57%

Other monthly averages

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Current (hourly) weather 15 day forecast

Boulder weather stats

Boulder weather statistics
Hottest month: July 29.2°C 84.6°F
Driest month: January 17mm 0.7ins
Sunniest month: September 9.6hrs
Coldest month: January 5.5°C 41.9°F
Wettest month: May 78mm 3.1ins
Warmest sea: August 18.4°C 65.1°F
Map showing location of Boulder (40.01499, -105.27055) Boulder map pin © Google

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