Climate in Oceanside (California)

The climate of Oceanside is arid sub-tropical, with very mild, relatively rainy winters and warm, sunny summers.
The city is located on the coast of California, in the northern part of San Diego County, in an urban agglomeration that also includes the cities of Vista and Carlsbad. Like in San Diego, the climate is very mild due to the cold current flowing in the ocean.
Here too, however, the temperature can rise a lot when the Santa Ana wind blows from the deserts areas of the interior. On average, there are only 5 days with a maximum temperature equal to or above 32 °C (90 °F). On the hottest days of the year, the temperature normally reaches 37/38 °C (99/100 °F), usually in September or October, but during some years it does not exceed 33/34 °C (91/93 °F). However, in September 2010 it reached 40.5 °C (105 °F).
In winter, there are several sunny days and some periods of bad weather. In good weather, the temperature can drop to 0 °C (32 °F) or slightly below at night, but during the day the air becomes mild.
The average temperature of the coldest month (December) is of 11.6 °C (53 °F), that of the warmest month (August) is of 21.2 °C (70 °F). Here are the average temperatures.

These temperatures were measured at the airport, which is 4 km (2.5 mi) away from the coast. On the seafront, the temperature in summer is even lower, so much so that it often remains around 20 °C (68 °F) even in July and August. In winter, on the other hand, nights are milder, and in practice the temperature never drops below freezing. Here are the average temperatures in front of the port.

Precipitation amounts to 300 millimeters (11.9 inches) per year: it is therefore scarce. It ranges from around 0 mm (0 in) in the driest months (July, August) to 75 mm (3 in) in the wettest (February). Here is the average precipitation.




For the amount of sunshine, we can refer to the data from San Diego. As you can see, there are about 3,000 hours of sunshine per year, so the amount of sunshine is very good. In May and June, fog can form, so the hours of sunshine decrease slightly.

The sea temperature ranges between 15 °C (59 °F) and 20.5 °C (69 °F): so, the sea remains a bit cold even in summer. Here are the average sea temperatures.

Best Time

Having a good climate, Oceanside can be visited all year round. However, from December to March, it can rain, and it can get a bit cold at night. In May and June, there may be morning mists. In summer, but especially in September and October, there can be very hot days, when the wind blows from the desert.
The best time to go to the beach is from July to October, when the sea is less cold.

Back to California.

Oceanside - Weather by month

Based on the period 1991-2020

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January is generally a mild month. However, there are remarkable differences between night and day. The average temperature is of 12 °C (54 °F), with a minimum of 4.7 °C (40.5 °F) and a maximum of 19.3 °C (66.7 °F).
On the coldest nights of the month, the temperature usually drops to around -0.5 °C (31.5 °F).
On the warmest days of the month, the temperature usually reaches around 27.5 °C (82 °F).
Precipitation amounts to 60 mm (2.4 in), distributed over 6 days.
The day lasts on average 10 hours and 20 minutes.
The average humidity is 69%.
The average wind speed is 6 kph (4 mph).
The average sea temperature is of 15 °C (59 °F). Therefore, the sea is cold for swimming.

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February is generally a mild month. However, there are remarkable differences between night and day. The average temperature is of 12.2 °C (54 °F), with a minimum of 5.6 °C (42.1 °F) and a maximum of 18.9 °C (66 °F).
On the coldest nights of the month, the temperature usually drops to around 0.5 °C (33 °F).
On the warmest days of the month, the temperature usually reaches around 26.5 °C (80 °F).
Precipitation amounts to 75 mm (3 in), distributed over 9 days.
The day lasts on average 11 hours and 0 minutes.
The average humidity is 71%. Hence, the air is normally humid.
The average wind speed is 7 kph (4 mph).
The average sea temperature is of 15 °C (59 °F). Therefore, the sea is cold for swimming.

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March is generally a mild month. The average temperature is of 13.5 °C (56 °F), with a minimum of 7.9 °C (46.2 °F) and a maximum of 19.1 °C (66.3 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 3 °C (37 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 27 °C (81 °F).
Precipitation amounts to 45 mm (1.8 in), distributed over 8 days.
The day lasts on average 12 hours and 0 minutes.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 7 kph (4 mph).
The average sea temperature is of 15 °C (59 °F). Therefore, the sea is cold for swimming.

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April is generally a very mild month. The average temperature is of 14.6 °C (58 °F), with a minimum of 8.7 °C (47.6 °F) and a maximum of 20.5 °C (68.9 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 3.5 °C (38.5 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 29 °C (84.5 °F).
Precipitation amounts to 20 mm (0.8 in), distributed over 5 days.
The day lasts on average 13 hours and 5 minutes.
The average humidity is 72%. Hence, the air is normally humid.
The average wind speed is 7 kph (5 mph).
The average sea temperature is of 15.5 °C (60 °F). Therefore, the sea is cold for swimming.

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May is generally a very mild month. The average temperature is of 16.7 °C (62 °F), with a minimum of 12.4 °C (54.4 °F) and a maximum of 21 °C (69.8 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 7.5 °C (45.5 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 27.5 °C (81 °F).
Precipitation amounts to 10 mm (0.4 in), distributed over 4 days.
The day lasts on average 13 hours and 55 minutes.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is 8 kph (5 mph).
The average sea temperature is of 16.5 °C (62 °F). Therefore, the sea is cold for swimming.

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June is generally a warm month. The average temperature is of 18.6 °C (65 °F), with a minimum of 14.6 °C (58.2 °F) and a maximum of 22.6 °C (72.7 °F).
On the coldest nights, the temperature usually drops to around 10 °C (50 °F).
On the warmest days, the temperature usually reaches around 27 °C (80.5 °F).
Precipitation amounts to only 5 mm (0.2 in), distributed over 2 days.
The day lasts on average 14 hours and 20 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 8 kph (5 mph).
The average sea temperature is of 18 °C (64.5 °F). Therefore, the sea is cold for swimming.

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July is generally a warm month. The average temperature is of 20.7 °C (69 °F), with a minimum of 16.7 °C (62.1 °F) and a maximum of 24.7 °C (76.5 °F).
On the coldest nights of the month, the temperature usually drops to around 13 °C (55 °F).
On the warmest days of the month, the temperature usually reaches around 29.5 °C (85.5 °F).
Precipitation amounts to only 0 mm (0 in), so on average it never rains in the whole month.
The day lasts on average 14 hours and 5 minutes. So the days are long.
The average humidity is 77%. Hence, the air is normally humid.
The average wind speed is 7 kph (5 mph).
The average sea temperature is of 20 °C (67.5 °F). Therefore, the sea is very cool for swimming.

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August, the warmest month of the year, is generally a warm month. The average temperature is of 21.2 °C (70 °F), with a minimum of 16.7 °C (62.1 °F) and a maximum of 25.7 °C (78.3 °F).
On the coldest nights of the month, the temperature usually drops to around 12.5 °C (54.5 °F).
On the warmest days of the month, the temperature usually reaches around 30 °C (85.5 °F).
Precipitation amounts to only 0 mm (0 in), so on average it never rains in the whole month.
The day lasts on average 13 hours and 20 minutes.
The average humidity is 77%. Hence, the air is normally humid.
The average wind speed is 7 kph (4 mph).
The average sea temperature is of 20.5 °C (69 °F). Therefore, the sea is cool for swimming.

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September is generally a warm month. The average temperature is of 20.3 °C (69 °F), with a minimum of 15.1 °C (59.2 °F) and a maximum of 25.4 °C (77.8 °F).
On the coldest nights, the temperature usually drops to around 10 °C (50 °F).
On the warmest days, the temperature usually reaches around 33.5 °C (92 °F).
Precipitation amounts to only 5 mm (0.2 in), distributed over 2 days.
The day lasts on average 12 hours and 20 minutes.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 7 kph (4 mph).
The average sea temperature is of 20.5 °C (68.5 °F). Therefore, the sea is cool for swimming.

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October is generally a very mild month. The average temperature is of 17.7 °C (64 °F), with a minimum of 11.4 °C (52.6 °F) and a maximum of 23.9 °C (75 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 5.5 °C (42 °F).
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 32.5 °C (91 °F).
Precipitation amounts to 15 mm (0.6 in), distributed over 5 days.
The day lasts on average 11 hours and 20 minutes.
The average humidity is 72%. Hence, the air is normally humid.
The average wind speed is 6 kph (4 mph).
The average sea temperature is of 19.5 °C (66.5 °F). Therefore, the sea is very cool for swimming.

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November is generally a mild month. However, there are remarkable differences between night and day. The average temperature is of 14.1 °C (57 °F), with a minimum of 6.6 °C (43.8 °F) and a maximum of 21.6 °C (70.9 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 1 °C (34 °F).
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 30.5 °C (86.5 °F).
Precipitation amounts to 20 mm (0.8 in), distributed over 6 days.
The day lasts on average 10 hours and 25 minutes.
The average humidity is 69%.
The average wind speed is 6 kph (4 mph).
The average sea temperature is of 17.5 °C (63.5 °F). Therefore, the sea is cold for swimming.

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December, the coldest month of the year, is generally a mild month. However, there are remarkable differences between night and day. The average temperature is of 11.6 °C (53 °F), with a minimum of 4.3 °C (39.8 °F) and a maximum of 18.9 °C (66.1 °F).
On the coldest nights of the month, the temperature usually drops to around -1 °C (30.5 °F).
On the warmest days of the month, the temperature usually reaches around 26 °C (78.5 °F).
Precipitation amounts to 50 mm (2 in), distributed over 7 days.
The day lasts on average 10 hours and 0 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
The average humidity is 71%. Hence, the air is normally humid.
The average wind speed is 6 kph (4 mph).
The average sea temperature is of 15.5 °C (60.5 °F). Therefore, the sea is cold for swimming.