Climate and monthly weather forecast
Port Costa, CA

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Weather in January

January, like December, is another mild winter month in Port Costa, California, with an average temperature ranging between min 43°F (6.1°C) and max 56.5°F (13.6°C). January's onset sees an average high-temperature of a still refreshing 56.5°F (13.6°C), exhibiting a slight fluctuation from the previous month. Weather in January »

Weather in February

February, the last month of the winter in Port Costa, is also a moderate month, with temperature in the range of an average high of 59.2°F (15.1°C) and an average low of 44.1°F (6.7°C). Port Costa, California, greets February with an average high-temperature of a still mild 59.2°F (15.1°C), marking a slight deviation from the preceding month. Weather in February »

Weather in March

The first month of the spring, March, is a refreshing month in Port Costa, California, with temperature in the range of an average low of 45°F (7.2°C) and an average high of 61.5°F (16.4°C). March welcomes an average high-temperature of a comfortable 61.5°F (16.4°C), not much different from the preceding month. Weather in March »

Weather in April

April, like March, in Port Costa, California, is another refreshing spring month, with an average temperature ranging between min 46.8°F (8.2°C) and max 66.7°F (19.3°C). The shift into April reveals an average high-temperature of a still comfortable 66.7°F (19.3°C), closely mirroring March's climate. Weather in April »

Weather in May

The last month of the spring, May, is an agreeable month in Port Costa, California, with an average temperature ranging between max 71.1°F (21.7°C) and min 49.8°F (9.9°C). The beginning of May records an average high-temperature of an agreeable 71.1°F (21.7°C), marking a negligible difference from April's 66.7°F (19.3°C). Weather in May »

Weather in June

The first month of the summer, June, is a warm month in Port Costa, California, with an average temperature fluctuating between 54.1°F (12.3°C) and 77.7°F (25.4°C). The onset of June introduces a subtle rise in the average high-temperature, nudging from a pleasant 71.1°F (21.7°C) in May to a moderately hot 77.7°F (25.4°C). Weather in June »

Weather in July

July, like June, in Port Costa, California, is another warm summer month, with temperature in the range of an average low of 55.4°F (13°C) and an average high of 80.1°F (26.7°C). The warmest period falls in July and September, when the average high-temperature reaches 80.1°F (26.7°C). Weather in July »

Weather in August

The last month of the summer, August, is also a moderately hot month in Port Costa, California, with an average temperature varying between 79.7°F (26.5°C) and 56.5°F (13.6°C). The onset of August notes an average high-temperature of a still warm 79.7°F (26.5°C), subtly shifted from July's 80.1°F (26.7°C). Weather in August »

Weather in September

September, the first month of the autumn in Port Costa, is also a moderately hot month, with temperature in the range of an average high of 80.1°F (26.7°C) and an average low of 56.3°F (13.5°C). Temperatures reach their maximum during July and September, recording an average high-temperature of 80.1°F (26.7°C). Weather in September »

Weather in October

October, like September, is an agreeable autumn month in Port Costa, California, with an average temperature ranging between min 54°F (12.2°C) and max 72.9°F (22.7°C). Port Costa's transition into October involves a gentle shift in temperature, receding from a warm 80.1°F (26.7°C) in September to a pleasant 72.9°F (22.7°C). Weather in October »

Weather in November

November, the last month of the autumn in Port Costa, is another comfortable month, with an average temperature ranging between max 63°F (17.2°C) and min 47.7°F (8.7°C). November shows a mild decline in the average high-temperature, falling from October's pleasant 72.9°F (22.7°C) to a comfortable 63°F (17.2°C). Weather in November »

Weather in December

The first month of the winter, December, is still a mild month in Port Costa, California, with an average temperature varying between 55.4°F (13°C) and 43.2°F (6.2°C). The coldest period is December, when temperatures fluctuate between an average high of 55.4°F (13°C) and a low of 43.2°F (6.2°C). Weather in December »
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Frequently asked questions

How much does it rain in Port Costa?

Throughout the year, there are 56.9 rainfall days, and 4.88" (124mm) of precipitation is accumulated.

What is the month with the lowest UV index in Port Costa?

January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index.

What is the wettest month in Port Costa?

February is the month with the most rainfall in Port Costa. Rain falls for 6.8 days and accumulates 1.14" (29mm) of precipitation.

What is the most humid month in Port Costa?

March is the most humid month in Port Costa, California, with an average relative humidity of 75%.

When is Daylight Saving Time (DST) in Port Costa?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts in Port Costa, California, and the time zone changes from PST to PDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from PDT to PST.

When are the longest days in Port Costa?

June has the longest days of the year in Port Costa, with an average of 14h and 48min of daylight.

What is the month with the highest UV index in Port Costa?

The month with the highest UV index in Port Costa is June, with an average maximum UV index of 6.

What time of the year is the hottest in Port Costa?

In Port Costa, California, the months of July and September register the average highest temperatures, peaking at 80.1°F (26.7°C).

What is the driest month in Port Costa?

July and August are months with the least rain in Port Costa when the rain falls for 1.5 days and typically aggregates up to 0.04" (1mm) of rain.

What month has the most sunshine in Port Costa?

With an average of 12h of sunshine, July has the most sunshine of the year in Port Costa, California.

What is the least humid month in Port Costa?

The months with the lowest humidity in Port Costa, California, are September and October, with an average relative humidity of 60%.

What part of the year is the coldest in Port Costa?

December, with an average high of 55.4°F (13°C) and a low of 43.2°F (6.2°C), signifies the coldest month of the year.

What is the month with the shortest days in Port Costa?

With an average of 9h and 36min of daylight, December has the shortest days of the year.

What is the month with the least sunshine in Port Costa?

The month with the least sunshine is December, with an average of 5.7h of sunshine.

Average temperature
Port Costa, CA

Average temperature - Port Costa, CA

The warmest months (with the highest average high temperature) are July and September (80.1°F).
The month with the lowest average high temperature is December (55.4°F).

The month with the highest average low temperature is August (56.5°F).
The coldest month (with the lowest average low temperature) is January (43°F).

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Average pressure
Port Costa, CA

Average pressure - Port Costa, CA

The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed
Port Costa, CA

Average wind speed - Port Costa, CA

The windiest month (with the highest average wind speed) is May (7.1mph).
The calmest month (with the lowest average wind speed) is November (4.6mph).

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Average humidity
Port Costa, CA

Average humidity - Port Costa, CA

The month with the highest relative humidity is March (75%).
The months with the lowest relative humidity are September and October (60%).

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Average rainfall
Port Costa, CA

Average rainfall - Port Costa, CA

The wettest month (with the highest rainfall) is February (1.14").
The driest months (with the least rainfall) are July and August (0.04").

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Average rainfall days
Port Costa, CA

Average rainfall days - Port Costa, CA

The month with the highest number of rainy days is March (10.2 days).
The month with the least rainy days is August (0.9 days).

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Average daylight / Average sunshine
Port Costa, CA

Average daylight / Average sunshine - Port Costa, CA

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).

The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).

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Average sunshine days
Port Costa, CA

Average sunshine days - Port Costa, CA

The month with the most sunshine days is July (27.2 days).
The month with the least sunshine days is March (18.8 days).

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Average UV index
Port Costa, CA

Average UV index - Port Costa, CA

The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).

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Average visibility
Port Costa, CA

Average visibility - Port Costa, CA

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

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Port Costa, California, USA

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