Average Weather For San Luis Obispo, California, USA

Location

This report describes the typical weather at the San Luis Obispo County Regional Airport (San Luis Obispo, California, United States) weather station over the course of an average year. It is based on the historical records from 1984 to 2012. Earlier records are either unavailable or unreliable.

San Luis Obispo, California has a mediterranean climate with dry warm summers and mild winters. The area within 25 mi of this station is covered by grasslands (58%), oceans and seas (29%), forests (8%), and shrublands (4%).

Temperature

Over the course of a year, the temperature typically varies from 40°F to 79°F and is rarely below 33°F or above 90°F.

Daily High and Low Temperature

The daily average low (blue) and high (red) temperature with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

The warm season lasts from June 25 to October 18 with an average daily high temperature above 76°F. The hottest day of the year is September 1, with an average high of 79°F and low of 55°F.

The cold season lasts from December 1 to March 13 with an average daily high temperature below 67°F. The coldest day of the year is December 22, with an average low of 40°F and high of 64°F.

Fraction of Time Spent in Various Temperature Bands

The average fraction of time spent in various temperature bands: frigid (below 15°F), freezing (15°F to 32°F), cold (32°F to 50°F), cool (50°F to 65°F), comfortable (65°F to 75°F), warm (75°F to 85°F), hot (85°F to 100°F) and sweltering (above 100°F).

Sun

The length of the day varies significantly over the course of the year. The shortest day is December 21 with 9:47 hours of daylight; the longest day is June 20 with 14:32 hours of daylight.

Daily Hours of Daylight and Twilight

The number of hours during which the Sun is visible (black line), with various degrees of daylight, twilight, and night, indicated by the color bands. From bottom (most yellow) to top (most gray): full daylight, solar twilight (Sun is visible but less than 6° from the horizon), civil twilight (Sun is not visible but is less than 6° below the horizon), nautical twilight (Sun is between 6° and 12° below the horizon), astronomical twilight (Sun is between 12° and 18° below the horizon), and full night.

The earliest sunrise is at 5:47am on June 14 and the latest sunset is at 8:22pm on June 26. The latest sunrise is at 7:27am 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.

Daily Sunrise & Sunset with Twilight and Daylight Savings Time

The solar day over the course of the year 2012 . From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (solar, civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight savings time are indicated by the "DST" labels.

Clouds

The median cloud cover ranges from 11% (mostly clear) to 42% (partly cloudy). The sky is cloudiest on August 18 and clearest on November 24. The clearer part of the year begins around September 30. The cloudier part of the year begins around January 20.

Median Cloud Cover

The median daily cloud cover (black line) with percentile bands (inner band from 40th to 60th percentile, outer band from 25th to 75th percentile).

On November 24, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 62% of the time, and overcast or mostly cloudy 28% of the time.

On August 18, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 36% of the time, and clear or mostly clear 52% of the time.

Cloud Cover Types

The fraction of time spent in each of the five sky cover categories. From top (most blue) to bottom (most gray), the categories are clear, mostly clear, partly cloudy, mostly cloudy, and overcast. Pink indicates missing data. Outside of the United States clear skies are often reported ambiguously, leading them to be lumped in with the missing data.

Precipitation

The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around February 15, occurring in 33% of days. Precipitation is least likely around August 20, occurring in 5% of days.

Probability of Precipitation at Some Point in the Day

The fraction of days in which various types of precipitation are observed. If more than one type of precipitation is reported in a given day, the more severe precipitation is counted. For example, if light rain is observed in the same day as a thunderstorm, that day counts towards the thunderstorm totals. The order of severity is from the top down in this graph, with the most severe at the bottom.

Over the entire year, the most common forms of precipitation are light rain, moderate rain, and drizzle.

Light rain is the most severe precipitation observed during 39% of those days with precipitation. It is most likely around February 20, when it is observed during 12% of all days.

Moderate rain is the most severe precipitation observed during 33% of those days with precipitation. It is most likely around February 5, when it is observed during 14% of all days.

Drizzle is the most severe precipitation observed during 13% of those days with precipitation. It is most likely around July 1, when it is observed during 4% of all days.

Types of Precipitation Throughout the Year

Relative frequency of various types of precipitation over the course of a typical year.

During the warm season, which lasts from June 25 to October 18, there is a 7% 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 (42% of days with precipitation have at worst drizzle), light rain (33%), moderate rain (13%), and thunderstorms (10%).

During the cold season, which lasts from December 1 to March 13, there is a 29% 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 (41% of days with precipitation have at worst moderate rain), light rain (38%), and heavy rain (12%).

Warm Season Precipitation

Cold Season Precipitation

Relative frequency of various types of precipitation during the warm and cold seasons respectively.

Snow

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.

Humidity

The relative humidity typically ranges from 40% (comfortable) to 96% (very humid) over the course of the year, rarely dropping below 17% (dry) and reaching as high as 100% (very humid).

The air is driest around November 23, at which time the relative humidity drops below 52% (mildly humid) three days out of four; it is most humid around February 27, exceeding 93% (very humid) three days out of four.

Relative Humidity

The average daily high (blue) and low (brown) relative humidity with percentile bands (inner bands from 25th to 75th percentile, outer bands from 10th to 90th percentile).

Dew Point

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 34°F (dry) to 57°F (comfortable) and is rarely below 22°F (dry) or above 60°F (comfortable).

The time of the year between February 28 and November 16 is the most comfortable, with dew points that are neither too dry nor too muggy.

Dew Point

The daily average low (blue) and high (red) dew point with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

Wind

Over the course of the year typical wind speeds vary from 0 mph to 20 mph (calm to fresh breeze), rarely exceeding 27 mph (strong breeze).

The highest average wind speed of 8 mph (gentle breeze) occurs around May 29, at which time the average daily maximum wind speed is 20 mph (fresh breeze).

The lowest average wind speed of 4 mph (light breeze) occurs around December 18, at which time the average daily maximum wind speed is 13 mph (moderate breeze).

Wind Speed

The average daily minimum (red), maximum (green), and average (black) wind speed with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).
The wind is most often out of the north west (28% of the time) and west (12% of the time). The wind is least often out of the north east (1% of the time), north (3% of the time), south west (3% of the time), south (4% of the time), and east (4% of the time).

Wind Directions Over the Entire Year

The fraction of time spent with the wind blowing from the various directions over the entire year. Values do not sum to 100% because the wind direction is undefined when the wind speed is zero.

Fraction of Time Spent with Various Wind Directions

The fraction of time spent with the wind blowing from the various directions on a daily basis. Stacked values do not always sum to 100% because the wind direction is undefined when the wind speed is zero.