Annual mean 7°C · wettest around May · prevailing wind NE
Warmest
25.8 °C
Coldest
-0.1 °C
Wettest
58%
Windiest
3.7 m/s
Prevailing
NE
3.0 m/s average
When this place is good five ratings · thirty-six ten-day sections · click a cell to read it
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Every reading
bars actual · line feels-like, °Cchance of rain, %wind speed, m/ssky covered, %
The average temperature in Boulder over the whole year is 7°C. July is the hottest month, with highs of about 25°C; January is the coldest, with lows of about -7°C. Boulder has no sharply defined rainy season: the chance of rain on a given day runs from 17% in July, the driest month, to 29% in May, the wettest. Winds in Boulder are highest in February, averaging 3.1 m/s (11 km/h), and lightest in September, at 1.9 m/s (7 km/h). The prevailing wind is from the NE. The clearest skies in Boulder come in September, when the sky is typically 22% covered; May is the cloudiest month, at 40%.
Month by month Boulder climate by month: average temperatures year round · click a month to read it
Month
High
Low
Feels like
Chance of rain
Cloud
Wind
Being outside
Sun
Walking
January
0°C
-7°C
-3°C
20%
32%
2.7 m/s
0
0
11
February
1°C
-6°C
-3°C
25%
33%
3.1 m/s
1
0
18
March
6°C
-3°C
3°C
22%
37%
2.8 m/s
6
0
34
April
9°C
0°C
7°C
23%
37%
2.8 m/s
23
0
52
May
14°C
6°C
13°C
29%
40%
2.2 m/s
46
5
64
June
22°C
12°C
22°C
19%
26%
2.2 m/s
62
38
41
July
25°C
14°C
26°C
17%
23%
2.0 m/s
46
65
18
August
24°C
12°C
24°C
17%
23%
2.0 m/s
57
57
26
September
21°C
8°C
20°C
26%
22%
1.9 m/s
65
30
48
October
13°C
2°C
11°C
25%
25%
2.3 m/s
39
1
61
November
7°C
-2°C
4°C
22%
24%
2.6 m/s
12
0
39
December
2°C
-5°C
-1°C
27%
26%
2.9 m/s
1
0
20
High and low are the warmest and coolest of four readings a day — midnight, 6am, noon and 6pm — so a true overnight low can sit a degree or two under them. Chance of rain, cloud and wind are the day’s average; feels-like and the three ratings (each out of 100: Good from 55, Ideal from 80) are read at midday.
Seasons, and the year in short Boulder weather by season
Year round, Boulder has days of about 0°C at their warmest in January, its coolest month, and 25°C in July, its warmest; the coolest hours of the day run from -7°C to 14°C through the year, and the average temperature over the year is 7°C around the clock. Rain is most likely around May and least likely around July. Every figure here is a decade of observations blended into one representative year, so it reads as what this date is usually like, not a forecast for one particular day.
Boulder weather in winterDecember to February
High 1°CLow -6°CRain 24%
Winter in Boulder has typical daily highs of about 1°C and lows of about -6°C, with a 24% chance of rain on a given day.
Boulder weather in springMarch to May
High 9°CLow 1°CRain 25%
Spring in Boulder has typical daily highs of about 9°C and lows of about 1°C, with a 25% chance of rain on a given day.
Boulder weather in summerJune to August
High 24°CLow 13°CRain 18%
Summer in Boulder has typical daily highs of about 24°C and lows of about 13°C, with a 18% chance of rain on a given day.
Boulder weather in autumnSeptember to November
High 13°CLow 3°CRain 24%
Autumn in Boulder has typical daily highs of about 13°C and lows of about 3°C, with a 24% chance of rain on a given day.
When is the rainy season in Boulder?
Boulder has no sharply defined rainy season: the chance of rain on a given day runs from 17% in July, the driest month, to 29% in May, the wettest.
What time of year is Boulder windiest?
Winds in Boulder are highest in February, averaging 3.1 m/s (11 km/h), and lightest in September, at 1.9 m/s (7 km/h). The prevailing wind is from the NE.
What is the average temperature in Boulder year round?
The average temperature in Boulder over the whole year is 7°C. July is the hottest month, with highs of about 25°C; January is the coldest, with lows of about -7°C.