Half Moon Bay weather by month
What a typical year looks like in Half Moon Bay, California: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at San Francisco International Airport, 18 km from Half Moon Bay; records cover 1945–2026.
The year at a glance
- Precipitation a year
- 19.6 in499 mm
- Snow a year
- Rare
- Last spring freeze
- Rare
- First fall freeze
- Rare
- Heating degree days
- 2,476
- Cooling degree days
- 201
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 38°3° (heating, 99%) and 90°32° (cooling, 1%).
Month by month
Half Moon Bay in January
Highs average 58°14° and lows 45°7°, with 3.9 in99 mm of precipitation in a typical January.
- Record high
- 74°23° (2015)
- Record low
- 26°−3° (1949)
- Heating degree days
- 426
- Cooling degree days
- 0
Half Moon Bay in February
Highs average 61°16° and lows 46°8°, with 4 in101 mm of precipitation in a typical February.
- Record high
- 78°26° (2022)
- Record low
- 30°−1° (1949)
- Heating degree days
- 323
- Cooling degree days
- 0
Half Moon Bay in March
Highs average 63°17° and lows 48°9°, with 2.7 in69 mm of precipitation in a typical March.
- Record high
- 89°32° (2026)
- Record low
- 31°−1° (1966)
- Heating degree days
- 296
- Cooling degree days
- 1
Half Moon Bay in April
Highs average 66°19° and lows 49°10°, with 1.4 in35 mm of precipitation in a typical April.
- Record high
- 92°33° (1981)
- Record low
- 36°2° (1955)
- Heating degree days
- 234
- Cooling degree days
- 5
Half Moon Bay in May
Highs average 68°20° and lows 52°11°, with 0.48 in12 mm of precipitation in a typical May.
- Record high
- 97°36° (1984)
- Record low
- 39°4° (1950)
- Heating degree days
- 170
- Cooling degree days
- 14
Half Moon Bay in June
Highs average 72°22° and lows 54°12°, with 0.14 in3.6 mm of precipitation in a typical June.
- Record high
- 105°41° (2000)
- Record low
- 43°6° (1954)
- Heating degree days
- 97
- Cooling degree days
- 23
Half Moon Bay in July
Highs average 73°23° and lows 55°13°, with 0 in0 mm of precipitation in a typical July.
- Record high
- 99°37° (1985)
- Record low
- 44°7° (1951)
- Heating degree days
- 58
- Cooling degree days
- 26
Half Moon Bay in August
Highs average 73°23° and lows 56°14°, with 0.04 in1 mm of precipitation in a typical August.
- Record high
- 99°37° (2010)
- Record low
- 45°7° (1952)
- Heating degree days
- 44
- Cooling degree days
- 41
Half Moon Bay in September
Highs average 75°24° and lows 56°13°, with 0.07 in1.8 mm of precipitation in a typical September.
- Record high
- 104°40° (2017)
- Record low
- 41°5° (1950)
- Heating degree days
- 46
- Cooling degree days
- 56
Half Moon Bay in OctoberThis month
Highs average 72°22° and lows 53°12°, with 0.79 in20 mm of precipitation in a typical October.
- Record high
- 99°37° (1987)
- Record low
- 37°3° (1949)
- Heating degree days
- 100
- Cooling degree days
- 33
Half Moon Bay in November
Highs average 64°18° and lows 49°9°, with 2 in52 mm of precipitation in a typical November.
- Record high
- 85°29° (1967)
- Record low
- 31°−1° (1954)
- Heating degree days
- 260
- Cooling degree days
- 2
Half Moon Bay in December
Highs average 58°15° and lows 45°7°, with 4.1 in105 mm of precipitation in a typical December.
- Record high
- 75°24° (1958)
- Record low
- 24°−4° (1972)
- Heating degree days
- 422
- Cooling degree days
- 0