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May Weather in Costa Mesa, United States

Last updated: June 24, 2025

In Costa Mesa, United States, the average temperature in May is a pleasant 18°C (64°F). Expect a range that can dip to a minimum of 11°C (52°F) and peaking at a warm 30°C (86°F). During this month, precipitation is recorded at 12 mm (0.5 in) over approximately 3 days, with an average humidity of 70%. Perfect weather for exploring!

May Temperature in Costa Mesa

In May in Costa Mesa, the average temperature is 18°C (64°F). The maximum can reach 30°C (86°F), while the minimum can drop to as low as 11°C (52°F). This pleasant weather makes it an ideal time for travelers to explore the sights and enjoy outdoor activities.

May Weather in Costa Mesa: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Costa Mesa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Costa Mesa, May typically has an average temperature of 18°C (64°F), with highs reaching up to 30°C (86°F) and lows dropping to around 11°C (52°F).
JanFebMarAprMayJunJulAugSepOctNovDec575759636467727372696357
Data source: Temperature data for Costa Mesa generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

May Precipitation in Costa Mesa

In Costa Mesa in May, the precipitation amount is 12 mm (0.5 in) during a span of 3 days.

May Precipitation Trends in Costa Mesa

The chart displays monthly precipitation patterns in Costa Mesa, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Costa Mesa, May typically receives around 12 mm (0.5 inches) of precipitation spread over approximately 3 days.
JanFebMarAprMayJunJulAugSepOctNovDec6552552312432391868
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Costa Mesa

In Costa Mesa in May humidity is 70%. With an average temperature of 18°C (64°F), this humidity feels like a sticky embrace, making outdoor excursions a bit more cumbersome and requiring frequent breaks to stay refreshed and hydrated.

May Average Humidity in Costa Mesa

This chart illustrates the average monthly humidity levels in Costa Mesa, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Costa Mesa is approximately 70%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec74%79%75%71%70%72%73%69%68%67%68%71%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Costa Mesa

In Costa Mesa in May, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Costa Mesa.

Maximum UV Index Levels in Costa Mesa for May

The chart shows the monthly maximum UV Index (UVI) for Costa Mesa in May, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In May, the maximum UV index in Costa Mesa typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec468101011111010754
Data source: Costa Mesa May UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How May Weather in Costa Mesa Compares to Other Months

Weather in Costa Mesa varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Costa Mesa, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Costa Mesa, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather14°C (57°F)65 mm (2.5 inches)74%moderate
February Weather14°C (58°F)52 mm (2.0 inches)79%high
March Weather15°C (60°F)55 mm (2.2 inches)75%very high
April Weather17°C (63°F)23 mm (0.9 inches)70%very high
May Weather18°C (64°F)12 mm (0.5 inches)70%very high
June Weather20°C (68°F)4 mm (0.2 inches)72%extreme
July Weather22°C (72°F)3 mm (0.1 inches)73%extreme
August Weather23°C (73°F)2 mm (0.1 inches)69%very high
September Weather22°C (72°F)3 mm (0.1 inches)68%very high
October Weather20°C (69°F)9 mm (0.4 inches)67%high
November Weather17°C (63°F)18 mm (0.7 inches)68%moderate
December Weather14°C (58°F)68 mm (2.7 inches)71%moderate

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