This report describes the typical weather at the Oakland International Airport (Oakland, California, United States) weather station over the course of an average year. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Oakland, California has a mediterranean climate with dry warm summers and mild winters. The area within 25 mi of this station is covered by grasslands (31%), oceans and seas (28%), built-up areas (19%), shrublands (10%), and forests (9%).
Over the course of a year, the temperature typically varies from 43°F to 72°F and is rarely below 36°F or above 82°F.
The warm season lasts from June 13 to October 22 with an average daily high temperature above 69°F. The hottest day of the year is September 2, with an average high of 72°F and low of 58°F.
The cold season lasts from December 3 to February 9 with an average daily high temperature below 58°F. The coldest day of the year is December 26, with an average low of 43°F and high of 55°F.
The length of the day varies significantly over the course of the year. The shortest day is December 21 with 9:34 hours of daylight; the longest day is June 20 with 14:46 hours of daylight.
The earliest sunrise is at 5:46am on June 13 and the latest sunset is at 8:35pm on June 27. The latest sunrise is at 7:37am on November 3 and the earliest sunset is at 4:49pm on December 8.
Daylight savings time (DST) is observed in this location during 2012, starting in the spring on March 11 and ending in the fall on November 4.
The median cloud cover ranges from 44% (partly cloudy) to 77% (partly cloudy). The sky is cloudiest on January 26 and clearest on September 26. The clearer part of the year begins around April 10. The cloudier part of the year begins around November 28.
On September 26, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 63% of the time, and overcast or mostly cloudy 37% of the time.
On January 26, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 69% of the time, and clear or mostly clear 31% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around February 2, occurring in 38% of days. Precipitation is least likely around August 2, occurring in 5% of days.
Over the entire year, the most common forms of precipitation are moderate rain, light rain, and drizzle.
Moderate rain is the most severe precipitation observed during 41% of those days with precipitation. It is most likely around February 1, when it is observed during 17% of all days.
Light rain is the most severe precipitation observed during 37% of those days with precipitation. It is most likely around February 25, when it is observed during 15% of all days.
Drizzle is the most severe precipitation observed during 11% of those days with precipitation. It is most likely around July 11, when it is observed during 4% of all days.
During the warm season, which lasts from June 13 to October 22, there is a 8% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of drizzle (35% of days with precipitation have at worst drizzle), light rain (33%), moderate rain (22%), and thunderstorms (7%).
During the cold season, which lasts from December 3 to February 9, there is a 34% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of moderate rain (46% of days with precipitation have at worst moderate rain), light rain (35%), heavy rain (9%), and drizzle (6%).
Either snow is exceptionally unlikely to fall at any time during the year at this location or this station does not reliably report precipitation types.
The relative humidity typically ranges from 54% (mildly humid) to 95% (very humid) over the course of the year, rarely dropping below 29% (dry) and reaching as high as 100% (very humid).
The air is driest around October 18, at which time the relative humidity drops below 66% (mildly humid) three days out of four; it is most humid around January 19, exceeding 92% (very humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a year, the dew point typically varies from 36°F (dry) to 59°F (comfortable) and is rarely below 26°F (dry) or above 62°F (mildy humid).
The time of the year between February 21 and November 24 is the most comfortable, with dew points that are neither too dry nor too muggy.
Over the course of the year typical wind speeds vary from 0 mph to 17 mph (calm to moderate breeze), rarely exceeding 24 mph (strong breeze).
The highest average wind speed of 10 mph (gentle breeze) occurs around May 18, at which time the average daily maximum wind speed is 17 mph (moderate breeze).
The lowest average wind speed of 7 mph (light breeze) occurs around November 10, at which time the average daily maximum wind speed is 12 mph (gentle breeze).