Half Moon Bay (CA) Monthly Rainfall & Precipitation
This page shows both the average monthly rainfall and the number of rainy days in Half Moon Bay, California, United States of America. The numbers reflect climate data gathered over a 30-year period, from 1990 to 2020. Now, let's explore all the details to give you a full picture.
Generally, Half Moon Bay experiences moderate precipitation patterns, averaging 625 mm (25 in) yearly. However, this average masks significant seasonal variation, including a distinct dry season during certain months that are clearly visible in our monthly breakdown below.
Monthly Precipitation Levels
The average number of days each month with precipitation (> 0.2 mm (0.01 in))
Significant seasonal changes in precipitation occur throughout the year. During the wettest month, December receives substantial rainfall, averaging 144 mm (5.7 in) of precipitation, recorded across 14 rainy days.
In contrast, the driest month, July brings less rainfall, with 3 mm (0.1 in) over 5 rainy days.
December, the wettest month, has a maximum daytime temperature of 15°C (59°F). The city receives 160 hours of sunshine in this period. During the driest month July you can expect a temperature of 21°C (70°F). For more detailed insights into the city's temperatures, visit our Half Moon Bay Temperature page.
Annual Rainfall in the United States of America: City Comparison
The map below shows the annual precipitation across the United States of America. You can also select the different months in case you are interested in a specific month.
heavy rainfall
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Half Moon Bay vs World: Rainfall Compared
Half Moon Bay's average annual precipitation is 625 mm (25 in). Let's compare this to some popular worldwide tourist destinations:
In Barcelona, Spain, the average annual precipitation is 644 mm (25 in), evenly distributed across the year with no extreme wet or dry seasons.
In Shanghai, China, the annual average precipitation is 1347 mm (53 in), with a humid subtropical climate.
In Tokyo, Japan, the average annual precipitation is 1528 mm (60 in), with significant summer rains due to typhoon season.
Mumbai, India, experiences a tropical monsoon climate with 1860 mm (73 in) of annual rainfall, with the majority of precipitation happening during the monsoon season from June to September.
Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.
Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.
- "Ginger" was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.
- The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm (15 inches) wide and 20 cm (7.9 inches) thick. The snowflake fell at Fort Keogh, Montana, USA, on 28 January 1887.
- The greatest snowfall recorded was on Mt. Rainier, Washington State, USA—over 31.5 meters (103 feet) fell during the winter of 1972.
For more detailed information about Half Moon Bay (CA)'s weather, including sunshine hours, humidity levels, and temperature data, visit our Half Moon Bay (CA) Climate page.
