The Fourth of July falls on a Tuesday this year, which can make the holiday weekend a four-day affair if you’re fortunate enough to take Monday off.  Whether your much-deserved break is three or four days long, the weather will be key.

The actual Fourth of July can have wide swings in weather. The term “hot as the 4th of July” is particularly apt in Portland since it was on that date in 1911 that Portland reached its all-time hottest temperature ever recorded: 103 degrees. This mark would be tied again on August 2nd 1975.  Contrast that with the coolest Fourth on record with temperatures falling into the lower 40s!

A summary of July 4th weather shows big swings in rainfall and temperatures have occurred. Dave Epstein

 

Earlier this week, we enjoyed a period of low humidity and comfortable temperatures.  However, the humidity has been slowly creeping up and will remain high into early Sunday before falling.  It’s this humidity and a frontal boundary stuck in the area which will help bring numerous showers to Maine and New Hampshire to start this long weekend.

Warm and humid air is stuck south of a warm front Friday afternoon. Dave Epstein

The problem is that very warm and humid air over southern New England is bumping up against cooler air to the north.  This contrast will bring at least two rounds of rain, some of it quite heavy, between Friday evening and Sunday morning.  Because of the expected rainfall, the National Weather Service has issues a flood watch for much of the area away from the coast.

Flood watches are posted for much of northern New England. Dave Epstein/NOAA Data

To the south of the warm front, in the humid air, there are a severe thunderstorm watches posted.  Some of these storms could bring strong damaging winds, hail and even a small tornado.  If you are traveling in New England this evening be aware of highly variable weather.


Day By Day Forecast

Overnight, look for rain showers and even embedded storms.  I don’t expect any severe weather in Maine as we are too far north of the warm and tropical air.  It will still feel very muggy.  Some of the rain could cause small stream flooding and street flooding as well.  This is especially true west of the foothills.

Saturday will feature a break in the showers in the morning, but a new area of rain is expected to move in during the afternoon or evening.  Again, this rain could be heavy and have some thunderstorms embedded in the main area. This continues overnight Saturday and into early Sunday.

Highs Sunday will be warmest over southern most Maine. NOAA-Gray, ME

Sunday, any morning showers will end and we can expect it to clear by the afternoon.  If the cold front moves steadily, the majority of Sunday will be very good in terms of weather.  You might even be able to head to the beach after the morning showers end.  This sets up Monday and Tuesday as the  pick days of the five-day period.   Monday and Tuesday appear to be dry and warm everywhere with sunshine and little or no risk of showers.  Humidity levels will be much lower than Friday, Saturday and Sunday and without rainfall, I would say these two days are the best for outdoor activities.