This report describes the typical weather at the Moffett Federal Airfield (Mountain View, California, United States) weather station over the course of an average year. It is based on the historical records from 2004 to 2012. Earlier records are either unavailable or unreliable.
Mountain View, California has a mediterranean climate with dry warm summers and mild winters. The area within 25 mi of this station is covered by grasslands (34%), forests (28%), built-up areas (16%), oceans and seas (11%), and shrublands (9%).
Over the course of a year, the temperature typically varies from 43°F to 79°F and is rarely below 37°F or above 88°F.
The warm season lasts from June 12 to October 5 with an average daily high temperature above 75°F. The hottest day of the year is September 1, with an average high of 79°F and low of 60°F.
The cold season lasts from November 26 to March 6 with an average daily high temperature below 62°F. The coldest day of the year is January 14, with an average low of 43°F and high of 58°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 14:45 hours of daylight.
The earliest sunrise is at 5:46am on June 11 and the latest sunset is at 8:34pm on June 29. The latest sunrise is at 7:35am on November 3 and the earliest sunset is at 4:50pm on December 7.
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 7% (clear) to 34% (mostly clear). The sky is cloudiest on February 20 and clearest on May 29. The clearer part of the year begins around March 27. The cloudier part of the year begins around July 19.
On May 29, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 79% of the time, and overcast or mostly cloudy 20% of the time.
On February 20, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 39% of the time, and clear or mostly clear 50% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around February 20, occurring in 37% of days. Precipitation is least likely around July 29, occurring in 1% of days.
Over the entire year, the most common forms of precipitation are light rain, moderate rain, and heavy rain.
Light rain is the most severe precipitation observed during 62% of those days with precipitation. It is most likely around January 25, when it is observed during 23% of all days.
Moderate rain is the most severe precipitation observed during 27% of those days with precipitation. It is most likely around February 5, when it is observed during 12% of all days.
Heavy rain is the most severe precipitation observed during 11% of those days with precipitation. It is most likely around March 14, when it is observed during 5% of all days.
During the warm season, which lasts from June 12 to October 5, there is a 3% 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 light rain (78% of days with precipitation have at worst light rain), moderate rain (11%), and heavy rain (11%).
During the cold season, which lasts from November 26 to March 6, 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 light rain (57% of days with precipitation have at worst light rain), moderate rain (31%), and heavy rain (11%).
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 41% (comfortable) to 90% (very humid) over the course of the year, rarely dropping below 24% (dry) and reaching as high as 98% (very humid).
The air is driest around October 2, at which time the relative humidity drops below 51% (mildly humid) three days out of four; it is most humid around February 20, exceeding 86% (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 35°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 April 23 and November 16 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 18 mph (calm to fresh breeze), rarely exceeding 21 mph (fresh breeze).
The highest average wind speed of 8 mph (light breeze) occurs around May 31, at which time the average daily maximum wind speed is 18 mph (fresh breeze).
The lowest average wind speed of 3 mph (light breeze) occurs around November 16, at which time the average daily maximum wind speed is 10 mph (gentle breeze).