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Nearly every record-high temperature reported over the last few days in the Los Angeles area are from weather stations “compromised by heat sources and heat sinks,” according to a veteran meteorologist.

“In my opinion, the data from these stations is worthless,” California-based meteorologist Anthony Watts wrote on his blog Watts Up With That.

That’s not to say Los Angeles wasn’t scorching hot. Temperatures in much of greater Los Angeles were in the triple digits, according to the National Weather Service.

On the contrary, what Watts claims is that artificial heat sources and sinks produce localized heat around weather stations, adding the few degrees necessary to qualify as records. In general, cities are warmer than surrounding countryside owing to the urban heat island effect.

For example, downtown Los Angeles reported a daily record high temperature of 108 degrees Fahrenheit on Friday. Watts, however, noted the weather station was on top of a parking garage surrounded by vehicles. The weather station was relocated to the University of Southern California (UCS) campus in 1999 where meteorologists said it would be less prone to extreme swings, but Watts said that station’s had problems in the past.

“The ASOS type station used at USC is notorious for producing false record highs where there aren’t any. For example, Honolulu and Tucson,” Watts wrote. “Look at all the service vehicles parked around it. One wonders recent record high that was claimed there is just another result of a vehicle being parked to close to it like the Ice Cream Truck debacle that denied a new all-time record high for Scotland a few days ago.”

U.K. meteorologists recently rejected a record-high temperature reading at Motherwell, Scotland, on June 28 because an ice cream truck had idled nearby with its engine on, possibly contaminating the reading.

Scotland’s record-high reading came amid what some are calling a global heat wave, which has produced record readings across the world. Some media outlets, including The Washington Post, tried to link the heat wave to man-made global warming.

“No single record, in isolation, can be attributed to global warming,” the Post reported, trying to link summer weather to global warming. “But collectively, these heat records are consistent with the kind of extremes we expect to see increase in a warming world.”

Record-high temperatures were also recorded at the Van Nuys Airport, the Burbank Airport and the University of California-Los Angeles (UCLA). Watts took issue with all of these record readings. (RELATED: Africa’s Hottest Temperature Ever Recorded Was Probably ‘Influenced By Man-Made Objects’)

“It’s another ASOS station snuggled between an industrial park, runway, road, and taxiway,” Watts wrote of the Van Nuys Airport weather station, which recorded 117 degrees Fahrenheit on Friday.

As for the Burbank Airport, Watts wrote that “the weather station is virtually surrounded by asphalt runways, taxiways, and aircraft parking ramps,” which means the “likelihood for the station to get in the middle of a [400-degree] jetwash is almost a certainty, being so close to taxiways with turns.”

Airports, like cities, tend to run hotter than surrounding areas because of runways, jet wash from airplanes, vehicles exhaust and other non-natural factors that can artificially raise temperatures.

UCLA’s weather station recorded a record 111 degrees Fahrenheit on Friday. However, Watts pointed out the university’s thermometer is one the roof of a building, likely being hit with artificial heat.

“UCLA’s weather station is on the roof of the Math Sciences/Atmospheric Sciences building,” Watts wrote. “Why? there’s no place else to put it. There’s hardly a free and open space left.”

Update: This article has been updated to reflect that the downtown Los Angeles weather station that recorded high temperatures was at UCS, not the Department of Water and Power.