Merrimack (NH) Weather & Climate: Best Time to Visit

The climate in Merrimack is known for significant temperature differences throughout the year, making the weather dynamic. Average maximum daytime temperatures range from a comfortable 29°C (84°F) in July, the warmest time of the year, to a very cold 1°C (34°F) during cooler months like January.

At night, you can expect temperatures ranging from 17°C (63°F) in July to around -9°C (16°F) during January.

Check out our detailed temperature page for more information.

Temperature ranges by month

Merrimack has a notably wet climate with abundant precipitation, recording 1210 mm (48 in) of rain/snowfall per year. Year-round, Merrimack has a balanced climate with minimal variation in precipitation. The difference between the wettest month, June, with 127 mm (5 in), and the driest month, January, with 79 mm (3.1 in), is minimal. For more details, please visit our Merrimack Precipitation page.

The mean monthly precipitation over the year, including rain, hail, and snow

The average number of days each month with precipitation

Seasonal changes in sunshine hours are quite dramatic in Merrimack. While July receives considerable daily sunshine with up to 9.8 hours, November marks the darkest time of the year, where sunshine is scarce with only 4.2 hours of sunlight per day.

Visit our detailed sunshine hours page for more information.

Monthly hours of sunshine

Daily hours of sunshine

The relative humidity is high throughout the year in Merrimack.

The city experiences its highest humidity in September, reaching 76%. In April, the humidity drops to its lowest level at 62%. What does this mean? Read our detailed page on humidity levels for further details.

Relative humidity over the year