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Average Weather in Rancho San Diego California, United States

In Rancho San Diego, the summers are short, warm, arid, and mostly clear and the winters are long, cool, and partly cloudy. Over the course of the year, the temperature typically varies from 42°F to 86°F and is rarely below 36°F or above 95°F.

Temperature

The hot season lasts for 2.8 months, from July 4 to September 27, with an average daily high temperature above 82°F. The hottest day of the year is August 24, with an average high of 86°F and low of 64°F.

The cool season lasts for 4.2 months, from November 28 to April 5, with an average daily high temperature below 71°F. The coldest day of the year is December 27, with an average low of 42°F and high of 67°F.

Average High and Low Temperature

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature

Average Hourly Temperature in Rancho San DiegoJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMcoldcoolwarmcomfortablevery cold
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.

Clouds

In Rancho San Diego, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Rancho San Diego begins around May 5 and lasts for 6.0 months, ending around November 3. On September 10, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 90% of the time, and overcast or mostly cloudy 10% of the time.

The cloudier part of the year begins around November 3 and lasts for 6.0 months, ending around May 5. On February 22, the cloudiest day of the year, the sky is overcast or mostly cloudy 45% of the time, and clear, mostly clear, or partly cloudy 55% of the time.

Cloud Cover Categories

Cloud Cover Categories in Rancho San DiegoclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Sep 1090%Sep 1090%Feb 2255%Feb 2255%May 573%May 573%Nov 373%Nov 373%clearovercastmostly clearpartly cloudymostly cloudy
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Rancho San Diego varies throughout the year.

The wetter season lasts 4.7 months, from November 18 to April 8, with a greater than 11% chance of a given day being a wet day. The chance of a wet day peaks at 21% on February 21.

The drier season lasts 7.3 months, from April 8 to November 18. The smallest chance of a wet day is 1% on June 26.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 21% on February 21.

Daily Chance of Precipitation

Daily Chance of Precipitation in Rancho San DiegowetwetdryJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Feb 2121%Feb 2121%Jun 261%Jun 261%Jan 117%Jan 117%Nov 1811%Nov 1811%Apr 811%Apr 811%rain
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Rancho San Diego experiences significant seasonal variation in monthly rainfall.

The rainy period of the year lasts for 6.1 months, from October 20 to April 24, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around February 20, with an average total accumulation of 2.5 inches.

The rainless period of the year lasts for 5.9 months, from April 24 to October 20. The least rain falls around June 18, with an average total accumulation of 0.0 inches.

Average Monthly Rainfall

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Sun

The length of the day in Rancho San Diego varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 60 minutes of daylight; the longest day is June 20, with 14 hours, 19 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight in Rancho San DiegoJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 7 minMar 2012 hr, 7 minMar 2014 hr, 19 minJun 2014 hr, 19 minJun 2012 hr, 8 minSep 2212 hr, 8 minSep 229 hr, 60 minDec 219 hr, 60 minDec 21nightnightday
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise is at 5:39 AM on June 12, and the latest sunrise is 1 hour, 29 minutes later at 7:08 AM on November 4. The earliest sunset is at 4:41 PM on December 3, and the latest sunset is 3 hours, 18 minutes later at 7:59 PM on June 29.

Daylight saving time (DST) is observed in Rancho San Diego during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in Rancho San DiegoJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 125:39 AMJun 125:39 AM7:59 PMJun 297:59 PMJun 29Dec 34:41 PMDec 34:41 PM7:08 AMNov 47:08 AMNov 4Mar 12DSTMar 12DSTDSTNov 5DSTNov 5daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2017. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.

Humidity

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The perceived humidity level in Rancho San Diego, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 4% of 4% throughout.

Humidity Comfort Levels

Humidity Comfort Levels in Rancho San DiegoJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Dec 260%Dec 260%Aug 247%Aug 247%humidhumidcomfortablecomfortabledrydrymuggymuggy
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

Wind

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Rancho San Diego experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 7.0 months, from November 12 to June 11, with average wind speeds of more than 7.0 miles per hour. The windiest day of the year is December 30, with an average hourly wind speed of 8.2 miles per hour.

The calmer time of year lasts for 5.0 months, from June 11 to November 12. The calmest day of the year is September 9, with an average hourly wind speed of 5.8 miles per hour.

Average Wind Speed

Average Wind Speed in Rancho San DiegowindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph2 mph4 mph6 mph8 mph10 mph12 mph14 mphDec 308.2 mphDec 308.2 mphSep 95.8 mphSep 95.8 mphJun 117.0 mphJun 117.0 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction in Rancho San Diego varies throughout the year.

The wind is most often from the west for 9.5 months, from February 2 to November 17, with a peak percentage of 80% on June 2. The wind is most often from the east for 2.5 months, from November 17 to February 2, with a peak percentage of 46% on January 1.

Wind Direction

Wind Direction in Rancho San DiegoEWEJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%westeastnorthsouth
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Water Temperature

Rancho San Diego is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences some seasonal variation over the course of the year.

The time of year with warmer water lasts for 2.9 months, from July 11 to October 7, with an average temperature above 68°F. The day of the year with the warmest water is August 24, with an average temperature of 70°F.

The time of year with cooler water lasts for 4.3 months, from December 9 to April 20, with an average temperature below 61°F. The day of the year with the coolest water is February 8, with an average temperature of 59°F.

Average Water Temperature

Average Water Temperature in Rancho San DiegowarmcoolcoolJanFebMarAprMayJunJulAugSepOctNovDec56°F58°F60°F62°F64°F66°F68°F70°F72°F74°FAug 2470°FAug 2470°F59°FFeb 859°FFeb 8Jul 1168°FJul 1168°FOct 768°FOct 768°FDec 961°FDec 961°FApr 2061°FApr 2061°F
The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.7 months, from April 25 to August 17, with an average daily incident shortwave energy per square meter above 7.4 kWh. The brightest day of the year is June 19, with an average of 8.5 kWh.

The darker period of the year lasts for 3.2 months, from November 6 to February 12, with an average daily incident shortwave energy per square meter below 4.2 kWh. The darkest day of the year is December 22, with an average of 3.1 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in Rancho San DiegobrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWh10 kWhJun 198.5 kWhJun 198.5 kWhDec 223.1 kWhDec 223.1 kWhApr 257.4 kWhApr 257.4 kWhAug 177.4 kWhAug 177.4 kWhNov 64.2 kWhNov 64.2 kWhFeb 124.2 kWhFeb 124.2 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Rancho San Diego are 32.747 deg latitude, -116.935 deg longitude, and 597 ft elevation.

The topography within 2 miles of Rancho San Diego contains significant variations in elevation, with a maximum elevation change of 686 feet and an average elevation above sea level of 534 feet. Within 10 miles contains significant variations in elevation (3,002 feet). Within 50 miles contains large variations in elevation (6,516 feet).

The area within 2 miles of Rancho San Diego is covered by artificial surfaces (65%) and shrubs (23%), within 10 miles by artificial surfaces (43%) and shrubs (42%), and within 50 miles by shrubs (46%) and water (32%).

Data Sources

This report illustrates the typical weather in Rancho San Diego, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There are 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Rancho San Diego.

For each station, the records are corrected for the elevation difference between that station and Rancho San Diego according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Rancho San Diego is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Rancho San Diego and a given station.

The stations contributing to this reconstruction are: Gillespie Field (67%, 9 kilometers, north); Brown Field Municipal Airport (29%, 20 kilometers, south); and Campo (3.8%, 46 kilometers, east).

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for aiports and weather stations are provided by AskGeo.com .

Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.