The best times to visit Portsmouth for ideal weather are
May 21st 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.
Portsmouth Travel Guide
Other Portsmouth Travel Info
Weather in Portsmouth
Average temperatures in Portsmouth 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 25th 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 Portsmouth, 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 83.5°F (28.6°C) with temperatures rarely dropping below 63.7°F (17.6°C) at night.
Portsmouth Temperatures (Fahrenheit)
Portsmouth Temperatures (Celsius)
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.
Portsmouth Perceived Temperature (F)
Portsmouth Perceived Temperature (C)
Average Portsmouth 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.
|Month||Avg. High (°F)||Avg. Mean (°F)||Avg. Low (°F)|
|Month||Avg. High (°C)||Avg. Mean (°C)||Avg. Low (°C)|
Precipitation (Rain or Snow)
If dry weather is what you’re after, the months with the lowest chance of significant precipitation in Portsmouth are September, May, and then April. 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 late December with an average of 2 days of significant precipitation the week of December 24th.
When can you find snow in Portsmouth? Weather stations report very large amounts of snow likely to be deepest around February, especially close to late January and early February. The best time to ski (if at all) in Portsmouth is often around around January 29th 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 Portsmouth.
Snow on the Ground
The graph below shows the average snow on the ground in Portsmouth (in).
Average Rain and Snow by Month
|Month||Daily Chance of Rain||Average Snow Depth (in)||Total Precipitation (in)|
|Month||Daily Chance of Rain||Average Snow Depth (cm)||Total Precipitation (cm)|
Humidity and Wind
Portsmouth has some slightly muggy months, with moderately humid months on the other side of the year. The least humid month is February (48.9% relative humidity), and the most humid month is September (67.7%).
Wind in Portsmouth is usually calm. The windiest month is March, followed by February and April. March’s average wind speed of around 7.9 knots (9.1 MPH or 14.7 KPH) is considered “a gentle 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 15.1 knots, which is considered a moderate breeze.
Relative Humidity (%)
The graph below shows the average % humidity by month in Portsmouth.
The graph below shows wind speed (max and average) in knots.
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||7.2||Gentle breeze||13.6||Significant breeze|
|Feb||7.7||Gentle breeze||14.3||Significant breeze|
|Mar||7.9||Gentle breeze||14.8||Significant breeze|
|Apr||7.7||Gentle breeze||14.8||Significant breeze|
|May||6.6||Light breeze||13.2||Significant breeze|
|Jun||5.9||Light breeze||11.9||Significant breeze|
|Jul||5.4||Light breeze||11.4||Significant breeze|
|Aug||5.3||Light breeze||11.1||Significant breeze|
|Sep||5.4||Light breeze||10.8||Significant breeze|
|Oct||6.3||Light breeze||12.3||Significant breeze|
|Nov||6.5||Light breeze||12.4||Significant breeze|
|Dec||7||Gentle breeze||12.9||Significant breeze|
Show Relative Humidity by Month
|Month||Avg. Relative Humidity|
Is it Safe to Travel to Portsmouth?
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 Portsmouth, NH, US 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 Portsmouth 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
Overall Portsmouth Travel Experience by Season
Spring (March through May)
Humidity and temperatures combine to make this season feel moderately cold. Highs range from 74.8°F (23.8°C) and 37.3°F (2.9°C) with far warmer temperatures in the later months. Rain is somewhat common with 6 to 8 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 8 days of precipitation per month. June – August is the busiest season for tourism in Portsmouth, so lodging and other accommodations may cost more than usual.
Fall (September through November)
Fall daily highs range from 79.4°F (26.3°C) and 45.8°F (7.7°C), which will feel chilly given the humidity and wind. It rains or snows a significant amount: 6 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 Portsmouth to be enjoyable for warm weather travelers. The average high during this season is between 43°F (6.1°C) and 31.3°F (-0.4°C). On average, it rains or snows a fair amount: 6 to 8 times per month. These times of year are the second busiest with tourists.