May weather forecast and climate
Hercules, CA

Weather in May

The last month of the spring, May, is a pleasant month in Hercules, California, with average temperature varying between 69.3°F (20.7°C) and 50.5°F (10.3°C).

Temperature

In May, the average high-temperature is relatively the same as in April - a pleasant 69.3°F (20.7°C). In Hercules, California, the average low-temperature is 50.5°F (10.3°C).

Humidity

In Hercules, California, the average relative humidity is 69%.

Rainfall

In Hercules, in May, during 4.3 rainfall days, 0.55" (14mm) of precipitation is typically accumulated. Throughout the year, there are 72.2 rainfall days, and 12.83" (326mm) of precipitation is accumulated.

Ocean temperature

In Hercules, California, the average seawater temperature is 53.1°F (11.7°C).
Note: Swimming in 53.1°F (11.7°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

Daylight

In May, the average length of the day in Hercules is 14.3h.

Sunshine

The average sunshine in Hercules is 10.6h.

UV index

April through September, with an average maximum UV index of 5, are months with the highest UV index in Hercules. A UV Index reading of 3 to 5 represents a medium health hazard from the exposure to the Sun's UV rays for the average person.
Note: The average daily UV index of 5 in May transform into the following instructions:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
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FAQ

What is the temperature in May in Hercules?

In May, in Hercules, the average high-temperature is 69.3°F (20.7°C), and the average low-temperature is 50.5°F (10.3°C).

What is the average humidity in May in Hercules?

The average relative humidity in May in Hercules is 69%.

How many days does it rain in May in Hercules?

In May, in Hercules, the rain falls for 4.3 days. Throughout May, 0.55" (14mm) of precipitation is accumulated.

What is the ocean temperature in May in Hercules?

In Hercules, the average seawater temperature in May is 53.1°F (11.7°C). At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

How many hours of daylight does Hercules have in May?

In May, the average length of the day is 14.3h.

How many hours of sunshine does Hercules have in May?

The average sunshine in May in Hercules, California, is 10.6h.

When is the highest UV index in Hercules?

Months with the highest UV index are April through September, with an average maximum UV index of 5.

What is the UV index reading in May in Hercules?

The average daily maximum UV index in May in Hercules, California, is 5. A UV Index reading of 3 to 5 represents a medium hazard to health from the exposure to the Sun's UV radiation.

Average temperature in May
Hercules, CA

Average temperature in May - Hercules, CA
  • Average high temperature in May: 69.3°F

The warmest month (with the highest average high temperature) is September (77.5°F).
The month with the lowest average high temperature is December (55.4°F).

  • Average low temperature in May: 50.5°F

The month with the highest average low temperature is August (56.8°F).
The coldest months (with the lowest average low temperature) are January and December (43.9°F).

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Average pressure in May
Hercules, CA

Average pressure in May - Hercules, CA
  • Average pressure in May: 29.98"

The month with the highest atmospheric pressure is January (30.13").
Months with the lowest atmospheric pressure are June, August and September (29.92").

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Average wind speed in May
Hercules, CA

Average wind speed in May - Hercules, CA
  • Average wind speed in May: 7.5mph

The windiest month (with the highest average wind speed) is May (7.5mph).
The calmest month (with the lowest average wind speed) is November (4.8mph).

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Average humidity in May
Hercules, CA

Average humidity in May - Hercules, CA
  • Average humidity in May: 69%

The month with the highest relative humidity is March (74%).
Months with the lowest relative humidity are September and October (63%).

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Average rainfall in May
Hercules, CA

Average rainfall in May - Hercules, CA
  • Average rainfall in May: 0.55"

The wettest month (with the highest rainfall) is February (2.76").
The driest months (with the least rainfall) are July and August (0.04").

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Average rainfall days in May
Hercules, CA

Average rainfall days in May - Hercules, CA
  • Average rainfall days in May: 4.3 days

The month with the highest number of rainy days is March (12.6 days).
The month with the least rainy days is August (1.1 days).

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Average sea temperature in May
Hercules, CA

Average sea temperature in May - Hercules, CA
  • Average sea temperature in May: 53°F

The best month for swimming (with the highest average sea temperature) is September (57°F).
The coldest month (with the lowest average sea temperature) is April (52.6°F).

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Average daylight in May /
Average sunshine in May
Hercules, CA

Average daylight in May / Average sunshine in May - Hercules, CA
  • Average daylight in May: 14.3h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.6h).

  • Average sunshine in May: 10.6h

The month with the most sunshine is July (Average sunshine: 11.9h).
The month with the least sunshine is December (Average sunshine: 5.7h).

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Average sunshine days in May
Hercules, CA

Average sunshine days in May - Hercules, CA
  • Average sunshine days in May: 24.3 days

The month with the most sunshine days is August (27.3 days).
The month with the least sunshine days is March (16.4 days).

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Average UV index in May
Hercules, CA

Average UV index in May - Hercules, CA
  • Average UV index in May: 5

Months with the highest UV index are April, May, June, July, August and September (UV index 5).
Months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in May
Hercules, CA

Average cloud cover in May - Hercules, CA
  • Average cloud cover in May: 26

The month with the most cloud cover is March (Cloud cover 37).
The month with the least cloud cover is July (Cloud cover 12).

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Average visibility in May
Hercules, CA

Average visibility in May - Hercules, CA
  • Average visibility in May: 6mi

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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