The best times to visit Merrimack Valley for ideal weather are

May 14th to October 7th

based on average temperature and humidity from NOAA (the National Oceanic and Atmospheric Administration). Read below for more weather and travel details.



Other Merrimack Valley Travel Info

Weather in Merrimack Valley


Average temperatures in Merrimack Valley vary drastically. Considering humidity, temperatures feel cold for about half of the year and otherwise nice with a chance of rain or snow throughout most of the year. The area is less temperate than some — in the 26th percentile for pleasant weather — compared to tourist destinations worldwide. Weeks with ideal weather are listed above. If you’re looking for the very warmest time to visit Merrimack Valley, the hottest months are July, August, and then June. See average monthly temperatures below. The warmest time of year is generally mid July where highs are regularly around 86.1°F (30.1°C) with temperatures rarely dropping below 65.3°F (18.5°C) at night.

Merrimack Valley Temperatures (Fahrenheit)


Merrimack Valley Temperatures (Celsius)


“Feels-Like” Temperatures

The way we experience weather isn’t all about temperature. Higher temperatures affect us much more at higher humidity, and colder temperatures feel piercing with high winds. Our perceived temperatures factor in humidity and wind chill to better represent how hot or cold the day feels to a person.

Merrimack Valley Perceived Temperature (F)


Merrimack Valley Perceived Temperature (C)



Average Merrimack Valley Temperatures by Month

Daily highs (averaged for the month) usually give the best indication of the weather. A significantly lower mean and low generally just means it gets colder at night.

Show Fahrenheit

Month Avg. High (°F) Avg. Mean (°F) Avg. Low (°F)
Jan 34.2 25.1 17.2
Feb 35.8 26.3 17.9
Mar 46.4 35.9 27.3
Apr 60.2 48.5 38.5
May 72.6 60.2 49.2
Jun 78.3 67.2 57.6
Jul 84.7 73.7 64.1
Aug 82.7 71.6 61.7
Sep 75.6 64.4 54.8
Oct 62.9 52.3 43.6
Nov 51.4 41.4 33.2
Dec 40.1 31.8 24.7

Show Celsius

Month Avg. High (°C) Avg. Mean (°C) Avg. Low (°C)
Jan 1.2 -3.8 -8.2
Feb 2.1 -3.2 -7.8
Mar 8 2.2 -2.6
Apr 15.7 9.2 3.6
May 22.6 15.7 9.6
Jun 25.7 19.6 14.2
Jul 29.3 23.2 17.8
Aug 28.2 22 16.5
Sep 24.2 18 12.7
Oct 17.2 11.3 6.4
Nov 10.8 5.2 0.7
Dec 4.5 -0.1 -4.1



Precipitation (Rain or Snow)

If dry weather is what you’re after, the months with the lowest chance of significant precipitation in Merrimack Valley are November, August, and then January. Note that we define “significant precipitation” as .1 inches or more in this section. The lowest chance of rain or snow occurs around late August to early September. For example, on the week of August 27th there is 1 day of precipitation on average. By contrast, it’s most likely to rain or snow in early to mid June with an average of 2 days of significant precipitation the week of June 11th.

When can you find snow in Merrimack Valley? Weather stations report very large amounts of snow likely to be deepest around February, especially close to early February. The best time to ski (if at all) in Merrimack Valley is often around around December 3rd when fresh powder is deepest. Please note that a value of 0 for snow in the graph below may either mean there was no snow, or that snow is unreported.

Chance of Precipitation

The graph below shows the % chance of rainy and snowy days in Merrimack Valley.

Days with precipitation

Snow on the Ground

The graph below shows the average snow on the ground in Merrimack Valley (in).

Snow depth

Average Rain and Snow by Month

Show Inches

Month Daily Chance of Rain Average Snow Depth (in) Total Precipitation (in)
Jan 19% 6.3 2.4
Feb 22% 10.9 3
Mar 22% 6.1 3.7
Apr 21% 2.1 3.2
May 24% 0 2.6
Jun 31% 0 4.5
Jul 25% 0 3.8
Aug 19% 0 4.1
Sep 23% 0 4
Oct 24% 4.7 4
Nov 18% 5.1 2.8
Dec 24% 4.6 3.6

Show Centimeters

Month Daily Chance of Rain Average Snow Depth (cm) Total Precipitation (cm)
Jan 19 16 6.1
Feb 22 27.7 7.6
Mar 22 15.5 9.4
Apr 21 5.3 8.1
May 24 0 6.6
Jun 31 0 11.4
Jul 25 0 9.7
Aug 19 0 10.4
Sep 23 0 10.2
Oct 24 11.9 10.2
Nov 18 13 7.1
Dec 24 11.7 9.1


Humidity and Wind

Merrimack Valley has some slightly muggy months, with moderately humid months on the other side of the year. The least humid month is April (43.2% relative humidity), and the most humid month is December (60.2%).

Wind in Merrimack Valley is usually calm. The windiest month is March, followed by April and February. March’s average wind speed of around 6.9 knots (7.9 MPH or 12.7 KPH) is considered “a light breeze.” Maximum sustained winds (the highest speed for the day lasting more than a few moments) are at their highest in late March where average top sustained speeds reach 14.6 knots, which is considered a moderate breeze.

Relative Humidity (%)

The graph below shows the average % humidity by month in Merrimack Valley.

Avg. Relative Humidity


The graph below shows wind speed (max and average) in knots.

Max Sustained Wind
Average Daily Wind

Average Wind Speeds

Show Wind Speeds

All wind speeds are in knots. 1 knot = 1.15 MPH or 1.85 KPH.

Month Avg. Wind Avg. Wind Feel Sustained High Wind High Wind Feel
Jan 5.8 Light breeze 12.5 Significant breeze
Feb 6.4 Light breeze 13.3 Significant breeze
Mar 6.9 Light breeze 13.8 Significant breeze
Apr 6.6 Light breeze 13.9 Significant breeze
May 5.8 Light breeze 12.6 Significant breeze
Jun 5.3 Light breeze 11.6 Significant breeze
Jul 5 Light breeze 11.6 Significant breeze
Aug 4.6 Light breeze 10.6 Gentle breeze
Sep 4.7 Light breeze 10.5 Significant breeze
Oct 5 Light breeze 11.4 Significant breeze
Nov 5.3 Light breeze 11.5 Significant breeze
Dec 5.7 Light breeze 11.8 Significant breeze

Show Relative Humidity by Month

Month Avg. Relative Humidity
Jan 51.4%
Feb 47.2%
Mar 45%
Apr 43.2%
May 49.2%
Jun 58.1%
Jul 58%
Aug 58%
Sep 59.9%
Oct 60.2%
Nov 55%
Dec 60.2%


Is it Safe to Travel to Merrimack Valley?

Our best data indicates this area is generally safe. As of Oct 07, 2019 there are no travel advisories or warnings for the United States; exercise normal security precautions. Check this page for any recent changes or regions to avoid: Travel Advice and Advisories. This advisory was last updated on Sep 23, 2019.


The Busiest and Least Crowded Months

The busiest month for tourism in Merrimack Valley, the United States is June, followed by August and September. Prices for hotels and flights will be most expensive during these months, though you can save if you purchase well in advance. Tourists are unlikely to visit Merrimack Valley in November. Those willing to visit at these times will likely find it the least expensive month.

Estimated Tourism by Month


Most Popular Months to Visit

Tourists Seeking Accommodations

Tourism graph is based on Google searches for services used by tourists relative to the rest of the year. Tourism data for this area is slightly extrapolated based on nearby areas. Displayed data is calculated relative to the peak, so a score of 56.3 in November means 56.3% of the tourists vs. June.



Overall Merrimack Valley Travel Experience by Season

Spring (March through May)

Humidity and temperatures combine to make this season feel moderately cold. Highs range from 77.8°F (25.4°C) and 37.4°F (3°C) with far warmer temperatures in the later months. Rain is somewhat common with 6 to 7 days of significant precipitation per month. Spring is fairly slow for tourism, which makes it a good time for those looking for deals.

Summer (June through August)

The middle-year months have very comfortable weather with high temperatures that are comfortable. These months see the most precipitation with 6 to 9 days of precipitation per month. June – August is the busiest season for tourism in Merrimack Valley, so lodging and other accommodations may cost more than usual.

Fall (September through November)

Fall daily highs range from 81.2°F (27.3°C) and 45.4°F (7.4°C), which will feel chilly given the humidity and wind. It rains or snows a significant amount: 5 to 7 days per month. Tourism is the slowest during these months due to the weather, so hotels may be affordably priced.

Winter (December through February)

Weather is far too cold this time of year in Merrimack Valley to be enjoyable for warm weather travelers. The average high during this season is between 42.2°F (5.7°C) and 30.6°F (-0.8°C). On average, it rains or snows a fair amount: 6 to 7 times per month. These times of year are the second busiest with tourists.


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