Thermometer’s Location Sparks Heated Debate

With back-to-back temperatures of 104 degrees over the weekend, residents in this seaside city earned the title of hottest city in America the hard way.

Now that a blistering November heat wave is breaking, however, some meteorologists are questioning whether Oxnard really was toastier than other heat-stricken Southern California communities.

After all, the National Weather Service thermometer that tracked the hot temperatures sits near the Oxnard Airport tarmac, which soaks in the sun and drives up the mercury--especially during heat waves.

On Saturday and Sunday, the temperatures there registered 104, the highest marks in the country.

But the weather service listed a second temperature for Oxnard on both days: 98 degrees.

That reading came from a thermometer in the soil at the weather service’s local headquarters in east Oxnard about three miles away.

Meanwhile, residents up the coast in Santa Ynez on Sunday roasted at 104 and several other cities reached triple digits--without numbers inflated by scorching asphalt, noted John Sherwin, a meteorologist with WeatherData Inc.

He suggested the federal weather forecasters might be giving Oxnard the hometown advantage.

“It’s just because it’s in their backyard,” said Sherwin, speaking from Wichita, Kan., where it was 57 degrees and windy Monday.

“It’s the hometown thing,” he added. “We don’t recognize it, because nobody lives in the airport. They live in communities. We’re going to go with 98.”

The suggestion that his agency favors Oxnard really steams National Weather Service meteorologist Vladimir Ryshko.

“That’s absurd,” Ryshko said. “Certainly, we don’t inflate temperatures arbitrarily. That serves no useful purpose.”

Ryshko said the notice about Oxnard being the hottest city in the nation was just an “FYI” and made clear the reading came at Oxnard Airport.

Not wanting to play down the heat, he added: “Actually, people do live right across the street from the airport.”

With a high-pressure system weakening and moving east, the airport temperature dropped to 95 on Monday, and the second Oxnard reading to 91.

Simi Valley experienced record heat when the mercury soared to 98, topping the previous mark of 94 in 1976. In Thousand Oaks, it was a somewhat cooler 89. And in Ventura, the mercury topped off at 90.

Today, highs in the low 80s along the coast and in the mid-80s inland are expected. Temperatures are expected to drop back into mid- to high 70s on Wednesday--still a few degrees higher than normal.

Both Sherwin and Ryshko agreed that airport locations can exaggerate temperatures, because such sites are “urban heat islands.” The concrete buildings and roads absorb the heat readily and register temperatures higher than in other parts of a city.

One notorious example, Sherwin said, is concrete laden-Newark, N.J., where an airport thermometer often reports temperatures 3 to 5 degrees higher than in nearby New York City.

What’s more, the National Weather Service relies heavily on airport sensors to gather temperature data. That is because the Federal Aviation Administration allows the weather service to oversee its temperature sensors. To land safely, pilots must have an idea of air density--a function of temperature--and the National Weather Service expertise helps keep pilots safe.

Even though airports can get hotter than most parts of a city, Ryshko said that the data is reliable. At any given moment in any city, temperatures fluctuate between 5 and 10 degrees, he said. So, Ryshko said, it is impossible to give a single, accurate reading for a whole city--let alone pick a perfect thermometer location.

“There’s no such thing,” he said, “as a perfect sensor site.”