This report describes the typical weather at the Brown Municipal Airport (San Diego, California, United States) weather station over the course of an average October. It is based on the historical records from 1984 to 2012. Earlier records are either unavailable or unreliable.
San Diego, California has a cold semi-arid steppe climate. The area within 25 mi of this station is covered by shrublands (60%), oceans and seas (27%), and built-up areas (11%).
The month of October is characterized by gradually falling daily high temperatures, with daily highs decreasing from 77°F to 72°F over the course of the month, exceeding 87°F or dropping below 65°F only one day in ten.
Over the course of October, the length of the day is gradually decreasing. From the start to the end of the month, the length of the day decreases by 57 minutes, implying an average day-over-day decrease of 1.8 minutes.
The shortest day of the month is October 31 with 10:53 hours of daylight; the longest day is October 1 with 11:49 hours of daylight.
The earliest sunrise is at 6:42am on October 1; the latest sunset is at 6:32pm on October 1; the latest sunrise is at 7:05am on October 31; the earliest sunset is at 5:58pm on October 31.
Daylight saving time is observed in 2012 but it neither starts nor ends in October, so the entire month is in daylight time.
The median cloud cover ranges from 19% (mostly clear) to 31% (mostly clear). The trend is for the sky to be clearing with the median cloud cover decreasing by 11% from the start to the end of the month.
On October 31, the clearest day of the month, the sky is clear, mostly clear, or partly cloudy 55% of the time, and overcast or mostly cloudy 27% of the time.
On October 11, the cloudiest day of the month, the sky is overcast, mostly cloudy, or partly cloudy 34% of the time, and clear or mostly clear 48% of the time.
The average probability that some form of precipitation will be observed in a given day is 10%, with little variation over the course of the month.
Throughout October, the most common forms of precipitation are light rain, moderate rain, and heavy rain.
Light rain is the most severe precipitation observed during 59% of those days with precipitation. It is most likely around October 21, when it is observed during 7% of all days.
Moderate rain is the most severe precipitation observed during 21% of those days with precipitation. It is most likely around October 30, when it is observed during 3% of all days.
Heavy rain is the most severe precipitation observed during 12% of those days with precipitation. It is most likely around October 31, when it is observed during 2% of all days.
Either snow is exceptionally unlikely to fall at this location in October or this station does not reliably report precipitation types.
The relative humidity typically ranges from 43% (comfortable) to 91% (very humid) over the course of a typical October, rarely dropping below 14% (very dry) and reaching as high as 100% (very humid).
The air is driest around October 31, at which time the relative humidity drops below 58% (mildly humid) three days out of four; it is most humid around October 1, rising above 88% (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 typical October, the dew point typically varies from 41°F (dry) to 60°F (comfortable) and is rarely below 23°F (dry) or above 65°F (mildy humid).
The time of the month between October 1 and October 31 is the most comfortable, with dew points that are neither too dry nor too muggy.
Over the course of October typical wind speeds vary from 0 mph to 12 mph (calm to gentle breeze), rarely exceeding 16 mph (moderate breeze).
The highest average wind speed of 5 mph (light breeze) occurs around October 31, at which time the average daily maximum wind speed is 12 mph (gentle breeze).
The lowest average wind speed of 5 mph (light breeze) occurs around October 6, at which time the average daily maximum wind speed is 12 mph (gentle breeze).