We asked Union-Tribune readers for your weather questions, and you obliged. Robert West sent us a simple and intriguing question: Why does Del Mar have the coldest temperatures on the San Diego County coastline?
I lived in Del Mar for many years and know that it can get chilly there, especially in January. But Oceanside Harbor regularly reports the coolest temperatures. It may have to do with where the official weather-keeping thermometers are located.
“The thermometer we rely on in Oceanside is located just inside the harbor, so the onshore winds really aren’t influenced by the warmth of the land,” said Miguel Miller, a forecaster at the National Weather Service.
“The thermometer in Del Mar is located near the Del Mar Highlands, more than a mile inland.”
I shook my head when Miller said that and replied, “But the main thermometer that weather service uses for San Diego is at the airport, which is on San Diego Bay. Wouldn’t that be just as cold?”
Miller explained that the airport thermometer is much farther inland than the one at Oceanside. He also noted that much of the wind that hits the airport arrives from the west-northwest, which means that it travels over parts of Point Loma and Mission Bay, where it picks up a little heat from the land. That’s part of the reason that the bay tends to be cooler than the near-shore waters.
I’ve also received email from readers wondering why the temperature that they record outside their homes often differs with the temperature reported by the weather service.
Forecasters say that temperatures can vary on a single street, or a single neighborhood, due to the topography and elevation of the land. So it shouldn’t be surprising that the temperature reported by the weather service is often different.
