Expect chilly weather this week on LI

Colder weather is on its way.

A high-pressure system will remain over Long Island and most of the Northeast region early Monday, keeping daytime temperatures in the mid 60s. But a cold front approaches later Monday, creating a period of rain and temperatures nearly 10 degrees below normal, according to Michael Silva, a meteorologist with the Upton-based National Weather Service.

A weak low-pressure system from the south and the converging cold front mean a chance of rain, between 20 percent and 60 percent, beginning after noon on Tuesday and into Wednesday, the service said.

Precipitation amounts could be between a quarter inch and half inch, according to the forecast.

Temperatures are expected to drop to the mid 50s, with overnight lows into the high 30s and low 40s.

Gusty winds up to 20 mph also are likely, the service said.

"It's that time of the year when these cold fronts move in and bring in a chill," Silva said.

The average daily temperature this time of year for Long Island MacArthur Airport in Ronkonkoma is 61 degrees, Silva said, so the approaching front will produce a noticeable drop.

The overnight low Monday at MacArthur was 39; Westhampton Beach reported and overnight low of 29, according to Silva.

By Thursday, another approaching cold front moves in, but dry, sunny weather is expected through the weekend. Daily highs will be in the mid to high 50s, with nighttime lows in the low 40s.