May weather forecast and climate
Saint Helena, CA

Weather in May

May, the last month of the spring, in Saint Helena, is a warm month, with temperature in the range of an average high of 74.1°F (23.4°C) and an average low of 46.9°F (8.3°C).

Temperature

In Saint Helena, California, the average high-temperature slightly increases, from an agreeable 68°F (20°C) in April, to a moderately hot 74.1°F (23.4°C). In May, the average low-temperature is 46.9°F (8.3°C).

Humidity

The average relative humidity in May is 64%.

Rainfall

In Saint Helena, in May, during 5.7 rainfall days, 0.87" (22mm) of precipitation is typically accumulated. In Saint Helena, during the entire year, the rain falls for 76.2 days and collects up to 16.93" (430mm) of precipitation.

Snowfall

January, February, April through December are months without snowfall in Saint Helena.

Daylight

The average length of the day in May is 14.3h.

Sunshine

In May, the average sunshine in Saint Helena is 10.2h.

UV index

In Saint Helena, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from unprotected exposure to the Sun's UV rays for ordinary individuals.
Note: The average daily UV index of 5 transform into the following instructions:
Take precautions - Protection against the skin and eye damage is obliged. 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 Saint Helena?

In Saint Helena, California, in May, the average high-temperature is 74.1°F (23.4°C), and the average low-temperature is 46.9°F (8.3°C).

What is the average humidity in May in Saint Helena?

In May, the average relative humidity in Saint Helena is 64%.

How much does it rain in Saint Helena in May?

In Saint Helena, California, in May, during 5.7 rainfall days, 0.87" (22mm) of precipitation is typically accumulated.

When it does not snow in Saint Helena?

In Saint Helena, California, snow does not fall in January, February, April through December.

How many hours of daylight does Saint Helena have in May?

In May, the average length of the day in Saint Helena, California, is 14.3h.

How many hours of sunshine does Saint Helena have in May?

In May, the average sunshine in Saint Helena is 10.2h.

What is the UV index reading in May in Saint Helena?

In May, the average daily maximum UV index in Saint Helena, California, is 5. A UV Index value of 3 to 5 symbolizes a medium health risk from the exposure to the Sun's UV rays.

Average temperature in May
Saint Helena, CA

Average temperature in May - Saint Helena, CA
  • Average high temperature in May: 74.1°F

The warmest month (with the highest average high temperature) is July (88.3°F).
The month with the lowest average high temperature is December (54.5°F).

  • Average low temperature in May: 46.9°F

The month with the highest average low temperature is September (54.3°F).
The coldest month (with the lowest average low temperature) is December (39.6°F).

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Average pressure in May
Saint Helena, CA

Average pressure in May - Saint Helena, CA
  • Average pressure in May: 29.97"

The month with the highest atmospheric pressure is January (30.14").
Months with the lowest atmospheric pressure are June, August and September (29.91").

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Average wind speed in May
Saint Helena, CA

Average wind speed in May - Saint Helena, CA
  • Average wind speed in May: 5.8mph

The windiest month (with the highest average wind speed) is May (5.8mph).
The calmest month (with the lowest average wind speed) is November (4.3mph).

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Average humidity in May
Saint Helena, CA

Average humidity in May - Saint Helena, CA
  • Average humidity in May: 64%

The month with the highest relative humidity is March (76%).
The month with the lowest relative humidity is September (53%).

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Average rainfall in May
Saint Helena, CA

Average rainfall in May - Saint Helena, CA
  • Average rainfall in May: 0.87"

The wettest month (with the highest rainfall) is February (3.7").
The driest month (with the least rainfall) is July (0").

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Average rainfall days in May
Saint Helena, CA

Average rainfall days in May - Saint Helena, CA
  • Average rainfall days in May: 5.7 days

The month with the highest number of rainy days is March (13.5 days).
The month with the least rainy days is August (0.3 days).

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Average snowfall in May
Saint Helena, CA

Average snowfall in May - Saint Helena, CA
  • Average snowfall in May: 0"

The month with the highest snowfall is March (0.04").
Months with the least snowfall are January, February, April, May, June, July, August, September, October, November and December (0").

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Average snowfall days in May
Saint Helena, CA

Average snowfall days in May - Saint Helena, CA
  • Average snowfall days in May: 0 days

The month with the highest number of snowfall days is March (0.2 days).
Months with the least snowfall days are January, February, April, May, June, July, August, September, October, November and December (0 days).

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Average daylight in May /
Average sunshine in May
Saint Helena, CA

Average daylight in May / Average sunshine in May - Saint Helena, 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: 9.5h).

  • Average sunshine in May: 10.2h

The month with the most sunshine is July (Average sunshine: 11.9h).
The month with the least sunshine is December (Average sunshine: 5.3h).

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Average sunshine days in May
Saint Helena, CA

Average sunshine days in May - Saint Helena, CA
  • Average sunshine days in May: 24.2 days

The month with the most sunshine days is July (30 days).
The month with the least sunshine days is March (15.9 days).

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Average UV index in May
Saint Helena, CA

Average UV index in May - Saint Helena, CA
  • Average UV index in May: 5

Months with the highest UV index are June, July and August (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 3).

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Average cloud cover in May
Saint Helena, CA

Average cloud cover in May - Saint Helena, CA
  • Average cloud cover in May: 29

The month with the most cloud cover is March (Cloud cover 44).
The month with the least cloud cover is July (Cloud cover 7).

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Average visibility in May
Saint Helena, CA

Average visibility in May - Saint Helena, CA
  • Average visibility in May: 6mi

Months with the highest visibility are February, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January and March (5mi).

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