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Half Moon Bay September Weather

Averages and records for weather in Half Moon Bay, California in the month of September.

Typical Half Moon Bay September Weather 1991–2020
Average daily high	66.5 °F
Average daily low	51.5 °F
Average monthly precipitation	0.2 inches
Average monthly snow	none
Daily chance of precipitation	20.4%
Daily chance of snow	0%

Half Moon Bay September Weather Records 1939–2024
Highest temperature	92 °F	September 25, 2019
Lowest temperature	35 °F	September 30, 2007
Highest daily low	70 °F	September 19, 1983
Lowest daily high	55 °F	September 3, 1962
Hottest average high temperature	72.3 °F	1958
Coldest average high temperature	62.0 °F	1955
Most daily precipitation	2.6 inches	September 19, 1959
Most monthly precipitation	3.7 inches	1959
Most daily snow	none	-
Most monthly snow	none	-

Note: Daily averages are a moving average which includes 14 days before and after

Day	Average (°F)		Record (°F)
Day	High	Low	High	Low
September 1	66.4	52.9	81	42
September 2	66.4	52.9	83	40
September 3	66.4	52.8	87	41
September 4	66.5	52.7	90	40
September 5	66.5	52.5	83	43
September 6	66.5	52.3	81	41
September 7	66.5	52.2	83	41
September 8	66.5	52.1	90	43
September 9	66.5	51.9	79	45
September 10	66.5	51.8	89	44
September 11	66.6	51.7	90	43
September 12	66.5	51.6	81	43
September 13	66.6	51.4	82	41
September 14	66.6	51.3	80	42
September 15	66.6	51.2	84	40
September 16	66.5	51.1	90	42
September 17	66.5	51.0	82	39
September 18	66.5	50.9	89	40
September 19	66.5	50.8	86	41
September 20	66.5	50.7	90	42
September 21	66.5	50.7	86	39
September 22	66.4	50.6	88	39
September 23	66.5	50.5	91	40
September 24	66.5	50.3	91	40
September 25	66.5	50.2	92	37
September 26	66.5	50.0	90	40
September 27	66.4	49.8	89	41
September 28	66.5	49.6	91	40
September 29	66.5	49.4	85	39
September 30	66.6	49.3	92	35

Weather Station Details

Years	Station	Coordinates
1939–2024	Half Moon Bay	location