Currently 68°F in Temecula, California, USA
72°F / 52°F
10 mph SW
Monday, May 20, 2024 5:41 PM PDT

About The Temecula Weather Pages

Updated October, 2004

Latitude: 33:27N Longitude: 117:05W Elevation (above sea level): 1194 feet

These pages track weather conditions, history, forecasts, news and events in Temecula, California. Currently temperature, precipitation, wind, relative humidity and barometric pressure readings appear on these pages. These readings are augmented by combined readings such as dewpoint, wind chill, and heat index. In late 2004, a web camera will be added to the site. WeatherCurrents is striving to provide comprehensive weather coverage in and around Riverside and San Diego counties, including neighboring communities Murrieta, Fallbrook, Hemet, Menifee and Lake Elsinore. Additional sites in the region are planned, see the main page for details. A local roundup is available to see weather data from all of sites at a glance. Other planned enhancements for the near future include graphs of the readings and tabular data of the readings for each day (much like the 36 hour summary). In the long term we hope to provide desktop replacement for the weather applet, which is currently very rudimentary, and we intend to utilize other sensors to automatically characterize the immediate local conditions (i.e. sunny, partly cloudy, fog, mist, light rain, etc.). There is more about how we plan to do this on the Frequently Asked Questions page. Stay tuned ...

Ultimeter 2000 Weather Station
Ultimeter 2000 Weather Station
(barometer inside)
The source of the feed used for these pages is a Peet Brothers Ultimeter 2100 Weather Station, with the sensors located in the backyard of a Redhawk area house. The combined temperature and humidity sensor (which replaced the original temperature only sensor in March, 2001) is appropriately shielded from wind, moisture, and sun. It is currently mounted on the outside of the deck approximately six feet from the rear of the house and about eleven feet off of the ground. The sensor is a solar shielded design for increased accuracy in adverse weather conditions. The new sensor is even more accurate than the older sensor which was deployed in the same general area.

Solar Shielded Temperature and Humidity Sensor
Temperature and Humidity
Sensor (solar shielded)
The humidity sensor produces readings within 5% of the true values, according to Peet Brothers. The readings are adversely affected by sprinkler activity in my yard and in neighboring yards. These effects are somewhat mitigated by the height of the sensor (eleven feet above ground). The humidity readings are also used to help calculate the dewpoint and the heat index. The dewpoint calculations are derived from code by Jeff Clymer.

The barometric pressure sensor is integrated into the Ultimeter 2100 keyboard and it's cousin, the Ultimeter 2000. An Ultimeter 2100 has been in used since November, 2003. From April, 2001 to November, 2003, an Ultimeter 2000 captured data on this site. Prior to April, 2001, I used an Ultimeter 800 keyboard which did not include the barometer (but was otherwise identical). The pressure sensor actually reports a relative value; it must be calibrated with a good value before it will operate. I used a barometric pressure value from the Weather Channel to calibrate it, after checking that value out against other local reports.

(wind speed and direction)
The wind sensor, called an anemometer, is mounted on a short (two foot) mast located on top of the chimney of the house. This is approximately six feet above the top of the roof. The installation guide recommends five feet or more to avoid turbulence from the roof. Wind data collection began in March, 2001. In addition to the wind speed and direction, wind gust speed is derived from this sensor's readings. Wind speed is also used to help determine wind chill.

Rain Gauge
Tipping Bucket Rain Gauge
The precipitation sensor (an Ultimeter Tipping Bucket rain gauge) is deployed at the edge of the backyard on the fence line. It is a self-emptying design and is capable of 0.01 inch measurements. The precipitation readings are very accurate with this instrument which meets National Weather Service specifications. This rain gauge replaced a similar wireless sensor deployed in November, 2001, which replaced the original Ultimeter Pro wired rain gauge, deployed in November, 2000. Both prior rain gauges had to be placed too close to the house, blocking any precipitation from the east. The original rain gauge was plagued with regular false readings. Precipitation data on this site began in November, 2000 and as of this writing there are nearly two complete seasons recorded.

Former Weather Data Capture Computer
Former Weather Data Capture Computer
I began recording data nearly continuously with this system on August 25, 1999. The Ultimeter 2100 Weather Station has several output modes using a serial port which you can see a cord coming out of on the side of the weather station. This system currently utilizes the continuous output mode, which produces current weather records on the serial port at 2400 bytes per second. A small desktop computer captures the serial data continuously and averages it every 30 seconds to produce a weather record. The current computer contains a Via C3 processor, consumes less than 30 watts of power and has been used continuously since December, 2002. From April, 2002 to December, 2002 I utilized a a PC104+ embedded form factor computer which you can see in the picture. Prior to April, 2002 a full-size PC was utilized to capture weather data from the weather station. The weather records are saved and shipped every thirty seconds from this computer to the web server, which maintains a complete archive. There are some gaps of a few hours here and there when the capture computer has needed maintenance or had a bug. Digital signatures are used to ensure that the web server is receiving authentic data. The archive is currently 190 megabytes in size (as of October, 2004) and growing at the rate of about 75 kilobytes per day.

Every now and then there is a failure in the capture and posting mechanisms. Typical sources of these problems include internet outages and sometimes equipment failures. I currently use cable modem service for my internet connection. This replaced wireless internet that I had used between April, 2002 and September, 2003, which in turn replaced a ISDN line that I had used for two and a half years prior to that. My entire setup, router/capture computer, cable modem and the weather station itself, is backed up with UPS equipment and should survive a power failure of four hours or more. When an internet outage happens and the capture computer can't communicate with the web server, data continues to be collected and stored on the capture computer until it can all be transfered to the web server. A watchdog program runs regularly on the web server, checking to see that data is still flowing, and emails me whenever there are problems. When problems do occur, you may see current data on the weather page that is a little out of date.

The serial capture and archival itself has proved highly reliable and after over five years of data capture, there should be very few bugs remaining (in fact I know of none currently). The capture software has run for months at a time without interruption.

Code to compute sunrise and sunset times was written by Kevin Boone. All the software is written custom for the site by John C. Toman.

The forecasts that appear on are now based on the NWS Temecula Forecast, which I look at daily, produced by the National Weather Service. I tailor this forecast slightly to the Temecula Valley based on the observations collected by Only slight tailoring is necessary at this point in time because my weather readings so closely match the National Weather Service readings taken at the fire station in Old Town Temecula. I began daily forecasting in September, 2001 when I received emails asking me what the most accurate forecast for the area was (the links on main page can have widely variant forecasts). Forecasting is difficult. Most of the time we're accurate, now and then we're not. first appeared on the internet in August, 2000 and is currently featured on the official City of Temecula home page, and on several other local web sites. The National Weather Service, San Diego office is currently using the data from WeatherCurrents sites to enhance their forecasting.

The Temecula weather pages are a service of WeatherCurrents. Temecula, California is located in the Temecula Valley, in southwestern Riverside County, along the Interstate 15 highway. The Temecula Valley's rolling hills are home to the Temecula wine country, vineyards, golf courses, a casino resort, and Old Town Temecula.
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