Portsmouth New Hampshire Climate Data

Monthly Average Climate Data for Portsmouth New Hampshire

Switch Data to Celsius/Metric Units
MonthAvg. LowAvg. HighAvg. Precip
January16.3 °F33.8 °F3.61 in.
February17.5 °F36.4 °F3.59 in.
March25.3 °F43.7 °F4.41 in.
April35.1 °F55.5 °F4.55 in.
May45.1 °F65.6 °F3.88 in.
June54.9 °F75.0 °F4.24 in.
July60.8 °F81.0 °F3.66 in.
August59.5 °F80.0 °F3.25 in.
September52.3 °F72.5 °F3.8 in.
October40.9 °F60.3 °F4.98 in.
November31.6 °F49.6 °F3.95 in.
December22.8 °F39.2 °F4.46 in.
Annual38.5 °F57.7 °F48.38 in.

Climate Data for Portsmouth New Hampshire

Average First Frost DateOct. 1 - Oct. 10
Average Last Frost DateMay 11 - May 20
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 ConditionsSevere Drought
Köppen Climate ClassificationDfb - Humid Continental Mild Summer, Wet All Year
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