Parts of Massachusetts could see snow but not until well after the kids are off the streets following a chilly Halloween night, according to the National Weather Service.

Trick or treaters may need to have extra layers on under their costumes when they start stalking about the neighborhoods for candy, as they will be greeted with highs only in the upper 40s in the Boston region.

Parts of western Massachusetts could even see snow overnight on Halloween, according to Alan Dunham, a meteorologist with the NWS.

“There is just a chance of some snow Tuesday night and Wednesday out in the Berkshires,” Dunham said.

To start the week, “rain is likely,” Dunham said, and the weather service predicts an 80% chance of showers for Boston from Sunday evening until early Monday afternoon.

Clouds will clear by Monday night, but temperatures won’t make it out of the low-50s through the day and will fall into the mid-30s heading into Tuesday.

On Tuesday, it will be cold despite “some sunny skies,” Dunham said. There is a slight chance of showers late in the evening, but well after the candy has been collected and the sugar has worn off.

Low temperatures overnight Tuesday are expected to be just above freezing, according to the NWS.

The chance of rain jumps to 50% by Wednesday due to a “little pressure well offshore,” Dunham said, but otherwise the day should be mostly sunny throughout the region. Temperatures Wednesday will stay in the mid-40s but fall below freezing overnight, according to the weather service.

Rain clears by Thursday, Dunham said, when the temperatures are expected to return to around 50 degrees under sunny skies. Lows will drop into the 30s overnight but should stay above freezing.

Slightly warmer weather returns for Friday, when it will be mostly sunny and in the mid-50s through much of the region. Overnight temperatures could stay close to 40 degrees.

A dry weekend is expected, Dunham said, with temperatures in the upper 50’s both Saturday and Sunday, but some clouds.

Not every neighborhood in Boston holds its trick or treating on Halloween night. For a long list of spooky offerings available in the city this week, visit https://www.boston.gov/news/bcyf-halloween-activities.

A baby dressed as a sunflower takes in the sights in downtown Salem Sunday. (Photo by Amanda Sabga//Boston Herald)
Teo Source, of Boston, reaches for a hug from Salem Satan on Sunday. (Photo by Amanda Sabga//Boston Herald)