Showers and thunderstorms Sunday could lead to flooding in Nassau and wet weather Islandwide through Monday morning, according to the National Weather Service.

A flash-flood watch will go into effect at 1 p.m. Sunday for Nassau County as showers and thunderstorms begin to develop, meteorologist Joey Picca at the National Weather Service in Upton said. No flood watch was issued for Suffolk although rain will eventually affect the whole island.

Isolated areas of precipitation are expected on Sunday afternoon, becoming widespread Sunday evening, Picca said.

"On average, areas could see anywhere from three-fourths of an inch to an inch of rain," Picca said of the region. "It's a pretty good rainfall rate."

Some areas could see high wind gusts coupled with the expected heavy rains, Picca said.

The flash-flood watch is scheduled to be lifted at 10 a.m. Monday.

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Highs on Sunday are expected to reach the mid-80s across the island, with slightly cooler temperatures on the East End.

Lows Sunday into Monday will drop into the mid-70s.

Showers could linger into Monday morning, snarling commuter traffic between 6 and 8 a.m., especially in Suffolk County, Picca said.

Temperatures on Monday will be in the mid-80s, with low temperatures in the mid- to upper 60s throughout most of the island.

The weather looks like it will dry out for the rest of the week, Picca said, with only a slight chance of showers on Wednesday.

For the rest of the week, temperatures will generally stay into the low to mid-80s during the day, with low temperatures in the mid- to upper 60s, Picca said.