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September weather forecast in Half Moon Bay

30 days Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

30 days Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Sun

Sunday

Mon

Monday

Tue

Tuesday

Wed

Wednesday

Thu

Thursday

Fri

Friday

Sat

Saturday

31 August, sun

	751 mmHg		85%
	5.3 m/s		+17

31 August, Sunday. day, 18°; night, 14°; clear

1 September, mon

	750 mmHg		84%
	5.1 m/s		+17

1 September, Monday. day, 19°; night, 14°; partly cloudy

2 September, tue

	750 mmHg		83%
	4.8 m/s		+17

2 September, Tuesday. day, 19°; night, 14°; clear

3 September, wed

	751 mmHg		83%
	4.9 m/s		+17

3 September, Wednesday. day, 19°; night, 14°; partly cloudy

4 September, thu

	751 mmHg		84%
	5.4 m/s		+17

4 September, Thursday. day, 18°; night, 14°; clear

5 September, fri

	751 mmHg		83%
	5.3 m/s		+17

5 September, Friday. day, 19°; night, 14°; clear

6 September, sat

	751 mmHg		82%
	5 m/s		+17

6 September, Saturday. day, 19°; night, 14°; clear

7 September, sun

	751 mmHg		82%
	4.9 m/s		+17

7 September, Sunday. day, 19°; night, 14°; clear

8 September, mon

	750 mmHg		83%
	5.2 m/s		+16

8 September, Monday. day, 19°; night, 14°; clear

9 September, tue

	750 mmHg		84%
	5.2 m/s		+17

9 September, Tuesday. day, 18°; night, 14°; partly cloudy

10 September, wed

	751 mmHg		84%
	5 m/s		+17

10 September, Wednesday. day, 18°; night, 13°; partly cloudy

11 September, thu

	751 mmHg		85%
	4.9 m/s		+17

11 September, Thursday. day, 18°; night, 14°; partly cloudy

12 September, fri

	751 mmHg		85%
	5.1 m/s		+16

12 September, Friday. day, 18°; night, 14°; partly cloudy

13 September, sat

	751 mmHg		84%
	4.9 m/s		+16

13 September, Saturday. day, 18°; night, 14°; overcast

14 September, sun

	751 mmHg		86%
	5 m/s		+16

14 September, Sunday. day, 17°; night, 14°; partly cloudy

15 September, mon

	752 mmHg		86%
	5.5 m/s		+16

15 September, Monday. day, 17°; night, 13°; overcast

16 September, tue

	752 mmHg		85%
	5.8 m/s		+16

16 September, Tuesday. day, 17°; night, 14°; partly cloudy

17 September, wed

	752 mmHg		85%
	5.7 m/s		+17

17 September, Wednesday. day, 18°; night, 14°; partly cloudy

18 September, thu

	751 mmHg		83%
	5.6 m/s		+16

18 September, Thursday. day, 18°; night, 14°; rain

19 September, fri

	751 mmHg		83%
	5.3 m/s		+17

19 September, Friday. day, 19°; night, 14°; clear

20 September, sat

	751 mmHg		82%
	5.1 m/s		+16

20 September, Saturday. day, 19°; night, 14°; clear

21 September, sun

	751 mmHg		82%
	5.1 m/s		+16

21 September, Sunday. day, 19°; night, 14°; clear

22 September, mon

	751 mmHg		83%
	5 m/s		+17

22 September, Monday. day, 18°; night, 13°; clear

23 September, tue

	752 mmHg		83%
	4.6 m/s		+17

23 September, Tuesday. day, 18°; night, 13°; clear

24 September, wed

	752 mmHg		83%
	4.69 m/s		+17

24 September, Wednesday. day, 19°; night, 14°; clear

25 September, thu

	752 mmHg		82%
	4.6 m/s		+17

25 September, Thursday. day, 19°; night, 14°; clear

26 September, fri

	752 mmHg		82%
	4.9 m/s		+17

26 September, Friday. day, 19°; night, 14°; clear

27 September, sat

	752 mmHg		82%
	4.9 m/s		+17

27 September, Saturday. day, 19°; night, 14°; clear

28 September, sun

	751 mmHg		82%
	5 m/s		+16

28 September, Sunday. day, 18°; night, 14°; partly cloudy

29 September, mon

	752 mmHg		83%
	5.2 m/s		+16

29 September, Monday. day, 18°; night, 13°; partly cloudy

30 September, tue

	752 mmHg		82%
	4.8 m/s		+16

30 September, Tuesday. day, 18°; night, 13°; partly cloudy

1 October, wed

	752 mmHg		81%
	4.8 m/s		+16

1 October, Wednesday. day, 18°; night, 14°; clear

2 October, thu

	752 mmHg		80%
	4.9 m/s		+16

2 October, Thursday. day, 18°; night, 13°; clear

3 October, fri

	752 mmHg		81%
	5.5 m/s		+15

3 October, Friday. day, 18°; night, 13°; clear

4 October, sat

	752 mmHg		79%
	5.8 m/s		+15

4 October, Saturday. day, 18°; night, 13°; clear

Average data for 10 years

Half Moon Bay September

15

sunny days

1

day with precipitation

2

cloudy days

15 sunny days; 1 day with precipitation; 2 cloudy days;

83

%

air humidity

3.1

m/s

WindW

4

mm of precipitation

(1% of annual average)

+17

°C

Water temperature

air humidity 83%; 4 millimeters of precipitation (1% of annual average); Wind westerly 3.1 Meters per second; Water temperature +17°

Weather graphs for September

TemperatureWater temperaturePrecipitation chance, %Humidity, %Wind, m/sPressure, mmHg

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W

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W

W

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W

W

W

W

W

W

W

W

W

W

W

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W

W

W

W

W

W

W

W

W

W

W

W

1

Average data for 10 years

2

3

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5

6

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9

10

11

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30

Daytime temperature

Night-time temperature

Cities near you

San Francisco
Sacramento
Oakland
Redding
Monterey
San Jose
Reno
Stanford
San Luis Obispo

Cities with similar weather in September

Sydney
Copenhagen
Vancouver
Looe
Bruges
Perth
San Sebastian
Liverpool
Brighton

The weather forecast for September 2025 is based on historical data from the past 10 years.

September in Half Moon Bay is the warmest month of the year. In September, the weather in Half Moon Bay is typically warm. Average daily high temperature in September is about 18 degrees above zero. On average, Half Moon Bay has 15 sunny, 12 partly cloudy, 2 cloudy, and 1 rainy day in September. The rains are usually light. September as well as August is considered the most comfortable time to visit Half Moon Bay.

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