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What happens if there are fewer May-gray days?

Rachel Clemesha/Scripps Institution of Oceanography
Rachel Clemesha
Scripps Pier is is shown with a marine layer of clouds over the Pacific Ocean in an undated photo.

It’s been called a natural air conditioner. The coastal cloud cover locals know as May gray and June gloom traditionally keeps spring and early summer temperatures comfortable in San Diego. But sidewalks, asphalt roads and rooftops are contributing to fewer foggy days along the coast.

"So we have linked that (decrease) to urban land cover — that is definitely a human change — and we can see that trend in decreasing number of fog days in May and June ... And the trend is stronger in those areas where we've done more to change the land cover," Rachel Clemesha, who studies marine layer clouds and California coastal climate with Scripps Institution of Oceanography, said.

Clemesha joined Midday Edition Monday to talk about the impact of fewer May-gray days.