Historical weather data, all-time temperature records, and monthly climate averages for Merrimack, NH. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in Merrimack runs a wide gamut — the date has seen everything from a balmy 80° in 2010 to a brutal 9° back in 1954. Expect something in between: a typical high of 52° and low of 30°, with a 40% chance of rain and just a 5% shot at snow.
Merrimack's weather history is not for the faint of heart. The thermometer has swung from a scorching 106° on July 4, 1911 to a bone-chilling -35° in February 1943 — a jaw-dropping 141-degree range. Add a 23-inch single-day snowfall in January 2015 and nearly 6 inches of rain in one September day in 1932, and you've got a town that's seen it all.
Merrimack earns its summers, with highs peaking around 84° in mid-July before the slow slide back to a frigid 33° average high in early January. If you're chasing warmth, aim for June through August; if you're avoiding precipitation, steer clear of late December, the wettest stretch of the year averaging over an inch per week.