Frequently Asked Questions

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Thursday, November 21, 2024 2:02 AM PST

Frequently Asked Questions

Updated November, 2011

Below are the questions that are asked the most about the Murrieta site. Didn't find your question here? Try the Temecula F.A.Q. or Ask!

Where is the Murrieta weather station located?

The Murrieta weather station readings are taken from the backyard of a home in the northwestern part of Murrieta, west of I15 and south of Bear Creek. The location is close to the western hills, on top of which is the Santa Rosa Plateau. It's about a mile northwest of Murrieta Valley High School.

Why are the readings from Murrieta generally warmer than Temecula in the mid-morning?

In short, it has to do with sensor placement and the exposure of the surrounding air mass to the sun. Unlike the Temecula weather station, the Murrieta temperature/humidity sensor is situated in an area that gets morning sun. This has the effect of warming the air around the sensor, which translates into higher temperatures. On cloudy mornings, Temecula and Murrieta are usually about the same. Even though the temperature sensor is solar-shielded (to prevent inaccurate readings from sun, wind and rain), the relatively warmer air around the sensor in the morning translates into higher temperatures on average in mid-morning than Temecula. Normally, by noon, the temperatures are similar, and then in the late afternoon, when the hills block the sun in Murrieta, Temecula becomes warmer because the air mass around it is still heated by the sun until sunset.

What is the normal seasonal rainfall for Murrieta?

The short answer is: we don't know for sure yet. It takes many years of rainfall data to come up with this number, and we only have data back to December, 2003.

However, an educated guess at the average seasonal rainfall at the northwest Murrieta weather station location is 14 inches. This guess is based on known ranges for southwest Riverside County, most parts of which get between 12 and 14 inches of rainfall on average. In ten years or so, we'll know if this guess is right!

Do you know of any sources for past rainfall data for Murrieta?

Unfortunately, no. However, it's possible that someone at the Murrieta County Water District, which covers the western part of Murrieta, may have rainfall data further back than December, 2003. If you know of any such past rainfall data, and you don't mind making it publicly available, please tell us and we'll make it available on this site.

Why is Murrieta so windy on spring and summer afternoons?

The phenomenon has a lot to do with topography, and also with the desert across the San Jacinto mountains. The heat in the desert causes low pressure, which draws ocean air across some of the inland valleys (air flows from higher to lower pressure). This is most pronounced in the afternoon, and usually ends in the evening. The result are our breezy afternoons, which help moderate the summer heat. Without them, Murrieta's and Temecula's climates would be a lot like Lake Elsinore or Hemet. Incidentally, those areas don't get the ocean breezes, largely because mountains block it. Southwest Riverside County thankfully has a few conduits to the coast, through the Rainbow gap, the Temecula gorge, and across the Santa Rosa plateau.

Are there any sources of weather data on the Santa Rosa Plateau?

The California Department of Forestry has operated a weather station in the Santa Rosa Plateau Reserve for several years. This station normally reports hourly, and is about three miles west of the Murrieta weather station. The Murrieta station's location in northwest Murrieta is near the foot of Cole Canyon, which leads right up into the plateau.

When has it snowed in Murrieta?

In the past decade, light dustings of snow have occurred in Murrieta and in La Cresta (to the west) on November 21, 2004 and on January 29, 2002. We believe the last snowfall before those two events was in 1985. Prior snowfall events in the Temecula Valley were in 1967, 1949, and 1882. There are probably several 20th century events missing from this list.

What are Murrieta's average ratings regarding ozone and particulate matter?

The quick answer is that we're not sure. There is (as of 2011) permanent air quality monitoring equipment in Temecula, and Temecula and Murrieta are lumped together as part of the Temecula Valley for air quality purposes. See this map for current readings. We don't think that values from one community to the other will be very different. Both benefit from a relatively clean air stream from the west, and are both south of the Elsinore convergence zone, which tends to hold back dirtier air to the north.