Half Moon Bay, California, United States Climate Change Severity

71
Very High
The current climate change severity in Half Moon Bay is Very High, with a 47.9% worsening in the climate score compared to last 15 years. This suggests deteriorating conditions, with increasing negative impacts on weather patterns and environmental conditions.
Data: Jan. to Aug. (Historical Vs 2025) - Weather Data Only
Low
020
Moderate
40
High
60
Very High
80
Extreme
100
°C (c)

Half Moon Bay Weather Condition Changes (Historic Vs 2025)

2025
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
Historic
2025

Over the past 15 year(s), Half Moon Bay temperature has changed by around -12.7%, and has experienced notable climate changes.

Sunny
Cloudy
Rainy
Snowy
Misty
Data: Jan. to Aug. (Historical Vs 2025)

Comparison of Weather Condition (Historic Vs 2025)

HistoricDays

Year 2025Days

Change

sunnySunny
826
-92.6%
cloudyCloudy
9123
-74.7%
rainyRainy
5147
-7.8%
snowySnowy
00
0%
mistyMisty
076
100%

Disclaimer: Other weather conditions not shown may affect the total day count.

Climate Change Indicators:

Over the past 15 years, Half Moon Bay has experienced measurable shifts in key climate parameters, contributing to the current severity score of 71 (within the Very High severity category). This suggests worsening climate conditions from the previous years. Here’s a breakdown of the specific changes observed:

Severity Score

71/100

Very High

Low
020
Moderate
40
High
60
Very High
80
Extreme
100

From 2010 to 2025, Half Moon Bay experienced significant changes:

Temperature change of

-1.7 °C

Variation in annual rainfall

-8.3 %

Change in average humidity

+11.7 %

PM2.5 levels surged by

-67.1 %

Heatwave changed by

-4.06 day(s)

Coldwave changed by

+27.1 day(s)

Wind speeds changed by

+0.1 km/h

These indicators show a dramatic increase in volatility and worsening conditions. Half Moon Bay's Very High severity status requires urgent and immediate adaptation and mitigation strategies, particularly focused on managing extreme weather events, improving air quality, and ensuring water resources are adequate for the population.

Check how we calculate Climate Change Severity
Based on data from Jan. to Aug.

Half Moon Bay Weather Forecast 30 Days (September - October 2025)
Half Moon Bay, California, United States

Condition
Temperature IconTemperature
Humidity Iconhumi.
Wind IconWind Speed
Mon. 8, Sep.
overcastOvercast
Temperature Icon19°/16°
Humidity Icon89%
Wind Icon13km/h
Tue. 9, Sep.
mistMist
Temperature Icon19°/15°
Humidity Icon91%
Wind Icon15km/h
Wed. 10, Sep.
overcastOvercast
Temperature Icon15°/14°
Humidity Icon94%
Wind Icon16km/h
Thu. 11, Sep.
patchy rain possiblePatchy rain nearby
Temperature Icon18°/14°
Humidity Icon85%
Wind Icon18km/h
Fri. 12, Sep.
patchy rain possiblePatchy rain nearby
Temperature Icon18°/14°
Humidity Icon83%
Wind Icon16km/h
Sat. 13, Sep.
partly cloudyPartly Cloudy
Temperature Icon19°/14°
Humidity Icon85%
Wind Icon15km/h
Sun. 14, Sep.
mistMist
Temperature Icon19°/15°
Humidity Icon88%
Wind Icon18km/h
Mon. 15, Sep.
sunnySunny
Temperature Icon18°/14°
Humidity Icon85%
Wind Icon17km/h
Tue. 16, Sep.
sunnySunny
Temperature Icon19°/14°
Humidity Icon81%
Wind Icon17km/h
Wed. 17, Sep.
sunnySunny
Temperature Icon21°/14°
Humidity Icon77%
Wind Icon19km/h
Thu. 18, Sep.
patchy rain possiblePatchy rain nearby
Temperature Icon19°/14°
Humidity Icon83%
Wind Icon10km/h
Fri. 19, Sep.
sunnySunny
Temperature Icon19°/14°
Humidity Icon85%
Wind Icon13km/h
Sat. 20, Sep.
sunnySunny
Temperature Icon19°/14°
Humidity Icon83%
Wind Icon10km/h
Sun. 21, Sep.
sunnySunny
Temperature Icon20°/13°
Humidity Icon79%
Wind Icon10km/h
Mon. 22, Sep.
patchy rain possiblePatchy rain possible
Temperature Icon20°/14°
Humidity Icon78%
Wind Icon18km/h
Tue. 23, Sep.
patchy rain possiblePatchy rain possible
Temperature Icon21°/14°
Humidity Icon76%
Wind Icon18km/h
Wed. 24, Sep.
sunnySunny
Temperature Icon22°/15°
Humidity Icon74%
Wind Icon16km/h
Thu. 25, Sep.
patchy rain possiblePatchy rain possible
Temperature Icon22°/15°
Humidity Icon72%
Wind Icon16km/h
Fri. 26, Sep.
patchy rain possiblePatchy rain possible
Temperature Icon22°/15°
Humidity Icon73%
Wind Icon18km/h
Sat. 27, Sep.
patchy rain possiblePatchy rain possible
Temperature Icon22°/15°
Humidity Icon72%
Wind Icon16km/h
Sun. 28, Sep.
patchy rain possiblePatchy rain possible
Temperature Icon21°/15°
Humidity Icon75%
Wind Icon17km/h
Mon. 29, Sep.
patchy rain possiblePatchy rain possible
Temperature Icon20°/14°
Humidity Icon79%
Wind Icon17km/h
Tue. 30, Sep.
patchy rain possiblePatchy rain possible
Temperature Icon20°/14°
Humidity Icon77%
Wind Icon17km/h
Wed. 1, Oct.
patchy rain possiblePatchy rain possible
Temperature Icon21°/14°
Humidity Icon72%
Wind Icon16km/h
Thu. 2, Oct.
patchy rain possiblePatchy rain possible
Temperature Icon21°/14°
Humidity Icon71%
Wind Icon17km/h
Fri. 3, Oct.
heavy rain at timesHeavy rain at times
Temperature Icon20°/14°
Humidity Icon71%
Wind Icon19km/h
Sat. 4, Oct.
patchy rain possiblePatchy rain possible
Temperature Icon20°/14°
Humidity Icon72%
Wind Icon18km/h
Sun. 5, Oct.
heavy rain at timesHeavy rain at times
Temperature Icon21°/14°
Humidity Icon70%
Wind Icon17km/h
Mon. 6, Oct.
moderate rain at timesModerate rain at times
Temperature Icon21°/14°
Humidity Icon70%
Wind Icon15km/h
Tue. 7, Oct.
sunnySunny
Temperature Icon20°/14°
Humidity Icon71%
Wind Icon17km/h
Wed. 8, Oct.
patchy rain possiblePatchy rain possible
Temperature Icon20°/14°
Humidity Icon74%
Wind Icon17km/h

Highest & Lowest Weather Forecasts

TemperatureTemperature

High will be onSat. 27, Sep.

22.2°C

Low will be onSun. 21, Sep.

13.3°C

HumidityHumidity

High will be onWed. 10, Sep.

94%

Low will be onSun. 5, Oct.

70%

Wind SpeedWind Speed

High will be onWed. 17, Sep.

18.7km/h

Low will be onThu. 18, Sep.

9.7km/h

PrecipitationPrecipitation

High will be onFri. 3, Oct.

1.1mm

Low will be onSat. 13, Sep.

0.01mm

Ultraviolet IndexUV

High will be onSat. 13, Sep.

5

Low will be onSun. 14, Sep.

4

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