Boulder Colorado Climate Data

Monthly Average Climate Data for Boulder Colorado

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January19.5 °F45.8 °F0.6 in.
February20.9 °F46.8 °F0.79 in.
March28.2 °F55.8 °F1.75 in.
April34.3 °F61.6 °F2.63 in.
May43.3 °F70.1 °F3.06 in.
June52.4 °F82.4 °F1.82 in.
July58.5 °F88.6 °F1.8 in.
August56.5 °F86.5 °F1.42 in.
September48.5 °F78.7 °F2.0 in.
October36.7 °F65.7 °F1.47 in.
November27.0 °F53.8 °F0.91 in.
December19.5 °F45.1 °F0.65 in.
Annual37.1 °F65.1 °F18.9 in.

Climate Data for Boulder Colorado

Average First Frost DateOct. 1 - Oct. 10
Average Last Frost DateMay 21 - May 31
Average Days With Frost125-150 Days
Plant Hardiness Zone - 2023Zone 6a : -10°F to -5°F
Plant Hardiness Zone - 2012Zone 6a : -10°F to -5°F
Current Drought ConditionsNormal
Köppen Climate ClassificationDfb - Humid Continental Mild Summer, Wet All Year