Late afternoon Monday brings the chance of isolated showers and thunderstorms into the overnight hours, with the potential for heavy rain locally, forecasters say.

Look for sunny skies Tuesday, with highs in the lower to mid-80s, for the East End and mid- to upper 80s for central and western Long Island, said Kevin Kacan, National Weather Service meteorologist in Upton.

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Tuesday also brings an expected high level of ozone, with an air-quality alert issued for 11 a.m. to 11 p.m. by the state Department of Environmental Conservation. Health officials advise people to limit strenuous outdoor activities, with the very young and people with pre-existing respiratory conditions especially at risk.

Humidity also starts building Tuesday, especially in the overnight hours, Kacan said.

In fact, most of this week is expected to be hot and muggy, said Rich Hoffman, News 12 Long Island meteorologist.

"While it will be hot this week, I don't see any record high temperatures," he said. The hottest day of the week "looks to be Wednesday, and the record high for July 29th is 96 in 2002."

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The weather service forecast calls for highs Wednesday in the low 90s.