ClimateAverages

Boulder Climate

Colorado, United States of America · population 107,349 · 397 weather stations within 200 km · records 1849 to 2025

Average annual daytime high
13.6°C
Warmest month · July
26.0°C
Typical daytime high
Coldest month · January
-10.3°C
Typical overnight low

Boulder has an average annual daytime high of 13.6°C, based on the 1951 to 1980 baseline. Its warmest month is July, when highs typically reach 26.0°C, and its coldest is January, with overnight lows near -10.3°C.

Month by month averages

MonthAvg highAvg low
January2.6°C-10.3°CColdest
February4.3°C-9.1°C
March6.6°C-7.1°C
April11.5°C-2.8°C
May17.2°C2.3°C
June23.0°C6.6°C
July26.0°C9.7°CWarmest
August24.8°C9.0°C
September20.9°C4.7°C
October15.2°C-0.3°C
November7.5°C-5.6°C
December3.9°C-8.7°C

Temperature range across the year

-12°-2°8°18°28°JanFebMarAprMayJunJulAugSepOctNovDec
Daytime high Overnight low
Hottest year on record
1933
+1.9°C vs. 1951–1980
Coldest year on record
1849
-2.5°C vs. 1951–1980

These figures reflect annual averages, not single-day records. Daily observations are outside this dataset's precision.

Is Boulder getting hotter?

Since 1900, Boulder's average temperature has risen by +1.4°C. Compared to the earliest station records that begin in 1849, warming totals +2.0°C.

5.6°6.1°6.6°7.1°7.6°1951–1980 baseline190019251950197520002025

20-year smoothed annual temperature reconstructed from station anomalies. Dashed line: 1951–1980 baseline.

Best time to visit
May to October

Daytime highs sit within a comfortable 15°C to 26°C range.

FAQ

What is the average temperature in Boulder?

Boulder's average annual daytime high is 13.6°C, based on the 1951 to 1980 baseline period. The warmest month is July, with highs averaging 26.0°C, and the coldest is January, with lows averaging -10.3°C.

What is the warmest month in Boulder?

July is the warmest month in Boulder, with typical daytime highs of 26.0°C.

What is the hottest year on record for Boulder?

1933 is the hottest year on record for Boulder, running +1.9°C above the 1951 to 1980 baseline.

Is Boulder getting hotter?

Yes. Since 1900, Boulder has warmed by roughly +1.4°C.

When is the best time to visit Boulder?

May to October typically offers the most comfortable daytime highs, in the 15°C to 26°C range.

Nearby cities

Baseline period 1951 to 1980. Monthly averages are the mean of station observations weighted by proximity. Warming trend is the 20-year smoothed anomaly against that baseline.