Frequently Asked Questions

Currently 51°F in Temecula, California, USA

Saturday, December 21, 2024 9:32 PM PST

Frequently Asked Questions

Updated November, 2011

Below are the questions that we get asked the most, and the best answers we can give. See Murrieta's FAQ as well. Didn't find your question here? Ask!

Where is the Temecula weather station located?

In the Redhawk area, near the intersections of Wolf Valley Road and Redhawk parkway.

Is There Any Information On Air Quality For the Temecula Region?

There is a forecast, but currently there are no actual reports. Several years ago, the South Coast Air Quality Management District, as of 2011, has re-established permanent monitoring equipment in the Temecula Valley. See this map for current, hourly readings. Prior to 2011, active monitoring had not taken place since 1996 or 1997. At that time, readings were in one of the local newspapers. A daily smog forecast is produced for the Temecula Valley and many other Southern California locations. This forecast is used by TemeculaWeather.com daily and is reported on the main page. The upshot is that the Temecula Valley rarely suffers from air quality problems except on the most extreme of days, and has some of the cleanest air in inland southern California. Sometimes there is particulate pollution (PM10), though, especially in late summer and early fall; that looks brown from a distance. Despite the growth in the Temecula Valley over the years, most air pollution is blown in rather than generated locally. On most summer days, the smog corridor is clearly visible to the north of the Temecula Valley, past Lake Elsinore towards Riverside.

What is the AQI?

The Air Quality Index (AQI) was devised by the Environmental Protection Agency (EPA) to indicate how polluted the air is by major pollutants. The pollutants used to produce an API reading are particulate matter (soot, dust, particles), sulfur dioxide, carbon monoxide, nitrogen dioxide, and ozone. How they are combined to produce an AQI is documented here. An online calculator is also available on the internet.

The most prevalent air pollutants in the Temecula Valley is PM10, which is particulate matter of an average of ten microns. Ozone is the second biggest pollutant in the Temecula Valley, but it is not a large problem.

The AQI scale is as follows:

0-50: Good air quality
51-100: Moderate air quality
101-200: Unhealthy air quality for sensitive persons
201-300: Unhealthy air quality
301-up: Hazardous air quality

Do You Have Any Air Quality Equipment?

Not right now. If there is inexpensive air quality equipment to be purchased, I would consider acquiring it for use on TemeculaWeather.com. There is some expensive equipment available ($1000s) that requires lots of active maintenance. If anyone comes across inexpensive, automatic ways of measuring air pollutants, please let me know.

Can I trust the Normal-Rainfall-To-Date Information on the site?

Not just yet, but it's getting there. There isn't enough complete rainfall seasons captured at this point in time (ten years worth at this writing). True normals require many, many years of readings (20 would be good).

What Is The Normal Seasonal Rainfall For Temecula?

It's going to vary depending on the spot, but in general, we've seen it listed as between 12" and 14", according to the Rancho California Water District. Most rainfall occurs in December, January, and February. The summers are normally dry, except for the occasional thunderstorm. Our location in South Temecula, as of December, 2010, reports normal annual rainfall as 13.65".

Precipitation data from November, 2000 on and the seasons starting July 1st is summarized on the Precipitation page, part of the archive.

Has It Ever Snowed In Temecula?

See the stories on this web site! Snow in the Temecula Valley is rare, and has occurred according to reports in 1882, January, 1949 (there used to be a story, written in 2002, on The Californian's website about this, but it appears to have been removed), December, 1967, 1985, in 2002, a major event on November 21st, 2004, and most recently a very brief event on March 11, 2006 which was much more significant in higher elevations of the Temecula Valley. I've been told via email that there is a picture of snowfall (thanks Gary Georgi) in the area from sometime around the turn of the century as well, a copy of this on the wall at the Temecula Brewing Company Restaurant. Thanks also to Pat Parkinson for digging up some of this information from the Fallbrook Historical Society.

Is There Anywhere Else On The Web Where Temecula Climate Data Can Be Found?

As far as I know, no. That's the main reason why TemeculaWeather.com came to exist. I noticed years ago that there was no local information, so I bought a weather station and slowly began to put together this web site and weather archive.

What are all of these forecasts? Which one is the best?

You will notice, if you look at a few, how different they are! My current knowledge is that none of the online reporting is actually local. However, on TV, The Weather Channel has local reports (I don't know where their equipment is located) which appear at the bottom of the screen. All online "local" weather reports are actually from Camp Pendleton, Oceanside, March ARB, or Riverside. There are airports in those locations that host weather equipment. The forecasts on the those web sites tend to be inaccurate as well, since most of them are actually targeted at surrounding areas and just borrowed for Temecula. The forecasts I trust the most (and base the TemeculaWeather.com forecast on) are put out by the National Weather Service - San Diego office, who also uses data from this site in their forecasting.

Is there a mold and pollen forecast for the Temecula Valley? Can you provide this information?

I don't currently have any equipment to measure pollen and mold counts. There also is not a specific local forecast online for this information, although there is a daily national forecast for tree, grass and weed pollen as well as mold spores at Allernet.com. I may try to contact them to get permission to use their information on this site. If anyone else discovers better sources, please let me know.

How come TemeculaWeather.com doesn't have a graphic depicting the current sky condition (i.e. clear, partly cloudy, fog, rain, etc.)? Can you add this?

The basic problem is this: the weather station doesn't provide this type of information. It can't, because it has no camera. However, I could use data from the weather station itself to determine if it's windy, or if it's raining. But I can't automatically determine if it's clear, sunny, partly cloudy, foggy, etc. Not without my eyeballs, which means I can't provide this kind of information at the moment. I assure you I don't have the time or inclination to manually update the current sky condition. Some weather stations will try to guess the condition without the video part, based upon the other instrument readings, and the results are not very good.

If you look on the About page (first paragraph!), you can read a little about my proposed solution. The idea is to capture stills regularly from a high-quality video camera (one that can work in low enough light for me to determine conditions at night as well as day). Then use some image processing and analysis to figure out what the conditions are. That, in conjunction with recent rainfall and wind data could yield current conditions automatically.

In short, it's a hard problem, it requires additional hardware and software, and you won't see it anytime soon as a result. I don't even have the camera yet (low lumens video cameras are $1100). I do believe this is important, though, and it is in my plans. Look for it at some point!

On some days the wind chill is actually higher than the air temperature. Why?

The wind chill index is designed to represent the apparent temperature to human skin based upon the air temperature and the wind speed. When temperatures are high, the higher the wind, the higher the wind chill, even above the actual air temperature. Have you ever noticed that hot winds make it seem hotter? This is opposite of wind's effect at lower temperatures, which is to make it seem colder than it actually is. The pivot point, where wind begins to influence the wind chill temperature above the actual temperature, occurs between 91°F and 92°F. From this point, the difference between wind chill and air temperture gets pronounced as the temperatures and wind speeds go up.

Can I Link My Web site To TemeculaWeather.com?

The more links directing web traffic this way the merrier! As a courtesy, please send me an email and tell me about your link, but in general anyone who wants to link their web site to TemeculaWeather.com is welcome to do so.

Can I submit my weather-related picture to TemeculaWeather.com for the home page?

Yes! Please send submissions via this web page. I try to replace the feature photo on the main page every two to three weeks, and I welcome all submissions. I can't publish every photo, however, and whether or not the photo is published is up to me, but if I like your photo there's a very good chance it will be featured for two to three weeks.

Some guidelines: The photo should be weather-related or related to current events around the Temecula Valley, and should be very current. It doesn't have to be taken in the Temecula Valley but should be in the local area. Take a look at the features page for examples of photos that made it.

Why is Temecula 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.

What is the prevailing wind direction in the Temecula Valley?

The afternoon breezes are westerly, so that would be west to east. As mentioned in the previous answer, the wind is sucked from the coast (from the west) to the deserts (to the east), especially in the summertime. You will see this mentioned in forecast as "onshore flow" and "afternoon breeze". We also get offshore flow, which is the reverse, but is not as common.

Are there local webcams?

Not anymore. There was a webcam operated by the USGS, that monitored the Santa Margarita River crossing near Sandia Creek Drive in De Luz, near the San Diego/Riverside county line. Vandalism has forced it out of operation. The Santa Margarita River is formed in Southwest Temecula where the Temecula and Murrieta Creeks come together.