Historical weather data, all-time temperature records, and monthly climate averages for Harwich, MA. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in Harwich runs cool, with an average high of just 50° and a low of 37° across 29 years of data. It's also a surprisingly wet date — there's a 62% chance of rain today, though snow is off the table. The range on this date is wild: a balmy 67° hit just this year, while 2016 bottomed out at 24°.
Harwich swings hard. Since 1996, temperatures here have ranged from a brutal -5° in January 2004 all the way up to 99° in July 1999 — a 104-degree spread. The wettest single day on record dropped 5.3 inches on September 9, 2021, a reminder that late-season storms can pack a serious punch on the Cape.
Summer is the sweet spot: the warmest week of the year runs July 16–22, with average highs around 80°. January and February are the coldest months, with highs barely cracking the upper 30s. If you're trying to dodge rain, avoid late March through early April — that stretch averages over an inch of precipitation per week, the wettest of the year.