Half Moon Bay (CA) Temperature by Month
Half Moon Bay in California, United States of America sees moderate seasonal temperature shifts, with daytime highs between 15°C (59°F) in December and 22°C (72°F) in September, averaging 19°C (66°F) annually. Explore the full monthly breakdown below.
Half Moon Bay Monthly Temperatures
The moderate changes in the climate in Half Moon Bay ensure gradual weather shifts through each season. At night, temperatures drop to between 11°C (52°F) and 6°C (43°F) depending on the time of year.
The chart below illustrates the average maximum day and minimum night temperatures in Half Moon Bay by month:
From around 4 AM to 6 AM temperatures are at their lowest; by 3 PM they've climbed to their daily peak. September, the warmest month, averages 270 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: Half Moon Bay vs the United States of America
The map below shows the annual temperature across the United States of America. You can also select individual months if you want to compare a specific time of year.
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Half Moon Bay vs World: Temperature Compared
Half Moon Bay's average annual maximum temperature is 19°C (66°F). To put that in context, here's how it compares to a few well-known destinations:
Barcelona, Spain has an annual average of around 21°C (70°F), with warm summers and mild, fairly short winters.
Queenstown, New Zealand averages 10°C (50°F) annually — remember seasons are flipped, so its coldest months fall in June and July.
Shanghai, China averages 21°C (70°F) a year, with warm summers, mild winters, and a noticeable spring and autumn.
Brisbane, Australia averages 26°C (79°F) a year, with warm winters and hot, humid summers.
What Does the Temperature Feel Like in Half Moon Bay?
Temperature alone doesn't tell the whole story — humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.
In Half Moon Bay, December is the coolest month, with average highs of 15°C (59°F) and humidity around 78% — considered high. For a full picture, see our humidity page.
Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.
The readings come from a range of sources — land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.
Seasonal temperature shifts influence more than just how warm it feels — they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.
Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in Half Moon Bay this rarely lasts long on the ground.
For more on Half Moon Bay's weather — including monthly rainfall, sunshine hours, and humidity — visit our Half Moon Bay climate page.
