Waltham Weather Outlook: August 20 – 27, 2026

A high chance of evening rains come through this weekend. Thursday night sees a 60% chance of rain, with a break during the day on Friday before seeing more rain Friday evening. Saturday shows chances of showers all day, with possible heavy rainfall and thunderstorms on Saturday night. We transition into milder rain on Sunday, and Monday ushers in warmer weather with seasonal lows in the high 50s and low 60s for the rest of the week.