Waltham Weather Outlook: July 2 – July 9, 2026

A dangerous and prolonged heat wave will continue across eastern Massachusetts through Saturday, with the most oppressive conditions occurring Thursday and Friday. Afternoon temperatures will climb into the upper 90s, while tropical humidity will push heat index values into the 100–110°F range. Overnight temperatures will offer little relief, remaining in the middle to upper 70s. An approaching cold front will increase the chance for showers and thunderstorms late Friday into Saturday. While confidence in the exact timing remains lower than average, any storms that develop could produce damaging wind gusts. Behind the front, a much more comfortable air mass settles into southern New England for the second half of the holiday weekend and much of next week, bringing seasonable temperatures, lower humidity, and mainly dry weather. A weak disturbance may bring a few showers around Tuesday, but widespread rainfall is not expected.