Climate and monthly weather forecastPortsmouth, VA
Climate and monthly weather forecast
The climate of Portsmouth
Portsmouth, located in Virginia, USA, predominantly exhibits a Humid subtropical climate according to the Köppen climate classification. This classification, symbolized as Cfa, implies that Portsmouth experiences no dry season, ensuring humidity remains relatively constant throughout the year. The geographical position of Portsmouth amplifies humid subtropical influences, offering warmer summers and milder winters.Throughout the year, temperatures in Portsmouth fluctuate from 34.7°F (1.5°C) in the colder months to 86.4°F (30.2°C) during the hotter seasons, making it a region with considerable thermal amplitude. Humidity sees slight variances as well, with recorded levels ranging from 74% to 78%, underscoring the prevalent humidity this region experiences. Rainfall tends to increase as the year progresses, peaking at 2.52" (64mm) in August with a minimum record of 1.1" (28mm) in November. Consistent with the subtropical climate, snowfall remains relatively insignificant with only minimal traces being noted in Winter and early Spring.
A peculiar weather pattern Portsmouth exhibits is the steadily increasing daylight hours from a low of 9.7 hours in December to a high of 14.7 hours by June, a notable feature characteristic of the northern hemisphere. Alongside this, sunshine duration escalates from 5.5 hours per day in Winter months to 10.9 hours per day in Summer. This directly influences the UV index which surges to 7 during the warmest months relative to a baseline of 2 in the colder months.
The best time to visit Portsmouth
The most pleasant period to visit Portsmouth falls from May to September, when the average temperatures oscillate between a pleasant 64.9°F (18.3°C) to a more tropical 86.4°F (30.2°C). This period also sees the highest sea temperatures, making it ideal for sea-side activities. Additionally, daylight hours are at their maximum during this period providing ample time for outdoor adventures and exploration.The worst time to visit Portsmouth
The period from December to February is the least advisable time to visit Portsmouth, with average temperatures being the lowest of the year, touching a mere 34.7°F (1.5°C) to 49.1°F (9.5°C). Despite relatively low humidity percentages during these months, increased rainfall coupled with the cold can lead to a rather damp and less hospitable climate.Spring weather in Portsmouth
Spring in Portsmouth, from March to May, is marked by a considerable rise in temperature, transitioning from 54.5°F (12.5°C) to 73.4°F (23°C). This period also witnesses a significant surge in rainfall from 1.34" (34mm) to 1.89" (48mm). Sea temperatures also rise from 47.2°F (8.4°C) to 61.6°F (16.4°C), signaling the onset of warmer waters.Summer weather in Portsmouth
The Summer season, from June to August, offers the warmest temperatures with averages ranging from 81.9°F (27.7°C) to 86.4°F (30.2°C). These months also bring the most rainfall, with measurements reaching 2.52" (64mm) in August. Sea temperatures rocket to their highest, reaching 72.5°F (22.5°C) to 80°F (26.7°C).Autumn weather in Portsmouth
Autumn, lasting from September to November, facilitates a cooling trend with temperatures falling from 79.2°F (26.2°C) to 58.3°F (14.6°C). Rainfall decreases gradually, falling to 1.1" (28mm) in November, the least amount of rainfall for the entire year.Winter weather in Portsmouth
Winter in Portsmouth, from December to February, experiences the lowest temperatures, dropping to an average minimum of 34.7°F (1.5°C). Rainfall shows an uptick, with February recording 1.42" (36mm) of precipitation. Despite the chilling atmosphere, snowfall remains insignificant, amounting only to 0.47" (12mm) in December and 0.39" (10mm) in February.Weather in January
A fresh start to the year in Portsmouth, Virginia, features weather conditions emblematic of a coastal winter. January weather provides cool temperatures with the average high and low of the month standing at 45.9°F (7.7°C) and 34.7°F (1.5°C) respectively. Weather in January »Weather in February
Transitioning from January, Portsmouth continues to experience chilly but slowly warming conditions in February. Along with a slight rise in temperature, the city encounters a small increase in rainfall, amounting to 1.42" (36mm). Weather in February »Weather in March
The first month of the spring, March, is a fresh month in Portsmouth, Virginia, with an average temperature ranging between max 54.5°F (12.5°C) and min 42.4°F (5.8°C). With the onset of March, Portsmouth observes a minor temperature ascent, with the average high-temperature adjusting from February's chilly 49.1°F (9.5°C) to a fresh 54.5°F (12.5°C). Weather in March »Weather in April
The blossoming month of April unfolds full tilt spring weather in Portsmouth. April is considerably warmer, enabling the flora around the city to bloom after a winter dormancy. However, April remains the cloudiest month with a cloud cover of 36%. Weather in April »Weather in May
The bright and bountiful month of May welcomes more consistent warmer temperatures in Portsmouth. Being the month with the highest humidity, May marks the commencement of the humid period which is characteristic to this coastal city. Weather in May »Weather in June
With the arrival of June, summer takes center stage in Portsmouth. This is the month where you can find an abundance of sunshine, longest daylight hours, and the temperature rise brings warmth to the city. Sea temperature climbs up, allowing residents and tourists to relish the beach to the fullest. Weather in June »Weather in July
July's illustrious zenith of the sunny season in Portsmouth brings forth the year's highest temperatures, averaging 86.4°F (30.2°C) as the high. A notable UV index of 7 indicates the health-aware populace about the intense sun. Picnics, barbecues, and outdoor activities dominate this part of the year. Weather in July »Weather in August
Portsmouth's coastal summer rolls into August with all its glory and warmth. Despite a slight drop in peak temperatures, August sustains July's dynamic summer weather pattern. The slight decrease in humidity, coupled with cooling sea breeze, subtly reveals the imminent approach of fall. Weather in August »Weather in September
In Portsmouth, September serves as a portal from the scorching summer to the mild fall season. A considerable decline in temperature from August's norm, the highest rainfall of the year at 2.28" (58mm), and longer nights resurrect the calmness and tranquillity of the city. Weather in September »Weather in October
October's arrival paints Portsmouth with hues of fall and brings pleasant weather for outdoor explorations. These weather attributes include less rainfall, moderate daytime temperatures, and crisp evenings reminiscent of a classic fall season. Weather in October »Weather in November
November adds a crisp chill in the air, initiating the arrival of winter in Portsmouth. The city welcomes an onset of cooler days with average temperatures starting to mimic the year’s lowest. It exemplifies the classic late autumn climate, with cooler nights demanding heavier jackets. Weather in November »Weather in December
Concluding the year in Portsmouth, December transforms the city into a winter wonderland. Winter's full onset is characterized by a general shift to shorter days and cold nights, with average temperatures dropping to their lowest: 51.4°F (10.8°C) and 40.5°F (4.7°C) respectively. Weather in December »Updated: Aug 26, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
With average temperatures fluctuating between a high of 45.9°F (7.7°C) and a low of 34.7°F (1.5°C), January stands out as the coldest month.
In Portsmouth, during the entire year, the rain falls for 151.9 days and collects up to 20.35" (517mm) of precipitation.
January through March, November and December are months with snowfall.
January is the month with the most snowfall. Snow falls for 2.2 days and accumulates 0.47" (12mm) of snow.
In Portsmouth, during the entire year, snow falls for 5.3 days and aggregates up to 1.18" (30mm) of snow.
With an average maximum UV index of 2, January is the month with the lowest UV index.
February is the month with the coldest seawater, with an average ocean temperature of 44.6°F (7°C).
With an average of 5.4h of sunshine, February has the least sunshine of the year in Portsmouth.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from EST to EDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from EDT to EST.
April through October are months without snowfall.
The most humid month in Portsmouth is May, with an average relative humidity of 78%.
The month with the longest days in Portsmouth is June, with an average of 14h and 36min of daylight.
July is the warmest month, with an average high-temperature of 86.4°F (30.2°C) and an average low-temperature of 73.6°F (23.1°C).
July and November, with an average relative humidity of 74%, are the least humid months.
July has the most sunshine of the year, with an average of 10.9h of sunshine.
July and August, with an average maximum UV index of 7, are months with the highest UV index in Portsmouth.
August is the month with the most rainfall. Rain falls for 16.9 days and accumulates 2.52" (64mm) of precipitation.
The month with the warmest seawater is August, with an average ocean temperature of 80.1°F (26.7°C).
November is the month with the least rainfall. Rain falls for 8.3 days and accumulates 1.1" (28mm) of precipitation.
With an average of 9h and 42min of daylight, December has the shortest days of the year.
Average temperature
Portsmouth, VA
The warmest month (with the highest average high temperature) is July (86.4°F).
The month with the lowest average high temperature is January (45.9°F).
The month with the highest average low temperature is July (73.6°F).
The coldest month (with the lowest average low temperature) is January (34.7°F).
Average pressure
Portsmouth, VA
- Average pressure in January:
30.11"Hg - Average pressure in February:
30.09"Hg - Average pressure in March:
30.08"Hg - Average pressure in April:
30.01"Hg - Average pressure in May:
30.03"Hg - Average pressure in June:
29.96"Hg
- Average pressure in July:
29.98"Hg - Average pressure in August:
29.99"Hg - Average pressure in September:
30.03"Hg - Average pressure in October:
30.03"Hg - Average pressure in November:
30.13"Hg - Average pressure in December:
30.12"Hg
The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.96"Hg).
Average wind speed
Portsmouth, VA
- Average wind speed in January:
10.1mph - Average wind speed in February:
10.2mph - Average wind speed in March:
10.5mph - Average wind speed in April:
10.5mph - Average wind speed in May:
9.1mph - Average wind speed in June:
8.4mph
- Average wind speed in July:
8mph - Average wind speed in August:
7.5mph - Average wind speed in September:
8.7mph - Average wind speed in October:
9.3mph - Average wind speed in November:
9.6mph - Average wind speed in December:
9.1mph
The windiest months (with the highest average wind speed) are March and April (10.5mph).
The calmest month (with the lowest average wind speed) is August (7.5mph).
Average humidity
Portsmouth, VA
The month with the highest relative humidity is May (78%).
The months with the lowest relative humidity are July and November (74%).
Average rainfall
Portsmouth, VA
- Average rainfall in January:
1.3" - Average rainfall in February:
1.42" - Average rainfall in March:
1.34" - Average rainfall in April:
1.46" - Average rainfall in May:
1.89" - Average rainfall in June:
1.81"
The wettest month (with the highest rainfall) is August (2.52").
The driest month (with the least rainfall) is November (1.1").
Average rainfall days
Portsmouth, VA
- Average rainfall days in January:
8.4 days - Average rainfall days in February:
10.3 days - Average rainfall days in March:
13.9 days - Average rainfall days in April:
13 days - Average rainfall days in May:
15.5 days - Average rainfall days in June:
14.5 days
- Average rainfall days in July:
17.4 days - Average rainfall days in August:
16.9 days - Average rainfall days in September:
13 days - Average rainfall days in October:
9.9 days - Average rainfall days in November:
8.3 days - Average rainfall days in December:
10.8 days
The month with the highest number of rainy days is July (17.4 days).
The month with the least rainy days is November (8.3 days).
Average snowfall
Portsmouth, VA
The month with the highest snowfall is January (0.47").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days
Portsmouth, VA
- Average snowfall days in January:
2.2 days - Average snowfall days in February:
1.5 days - Average snowfall days in March:
0.4 days - Average snowfall days in April:
0 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0 days - Average snowfall days in November:
0.3 days - Average snowfall days in December:
0.9 days
The month with the highest number of snowfall days is January (2.2 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average sea temperature
Portsmouth, VA
The best month for swimming (with the highest average sea temperature) is August (80°F).
The coldest month (with the lowest average sea temperature) is February (44.5°F).
Average daylight / Average sunshine
Portsmouth, VA
- Average daylight in January:
10h and 0min - Average daylight in February:
10h and 54min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 12min - Average daylight in May:
14h and 12min - Average daylight in June:
14h and 36min
- Average daylight in July:
14h and 24min - Average daylight in August:
13h and 30min - Average daylight in September:
12h and 24min - Average daylight in October:
11h and 12min - Average daylight in November:
10h and 12min - Average daylight in December:
9h and 42min
The month with the longest days is June (Average daylight: 14h and 36min).
The month with the shortest days is December (Average daylight: 9h and 42min).
- Average sunshine in January:
5h and 30min - Average sunshine in February:
5h and 24min - Average sunshine in March:
6h and 54min - Average sunshine in April:
9h and 36min - Average sunshine in May:
9h and 42min - Average sunshine in June:
10h and 48min
- Average sunshine in July:
10h and 54min - Average sunshine in August:
10h and 36min - Average sunshine in September:
9h and 24min - Average sunshine in October:
5h and 54min - Average sunshine in November:
5h and 42min - Average sunshine in December:
5h and 30min
The month with the most sunshine is July (Average sunshine: 10h and 54min).
The month with the least sunshine is February (Average sunshine: 5h and 24min).
Average sunshine days
Portsmouth, VA
- Average sunshine days in January:
19 days - Average sunshine days in February:
15.5 days - Average sunshine days in March:
15.3 days - Average sunshine days in April:
14.3 days - Average sunshine days in May:
12 days - Average sunshine days in June:
11 days
- Average sunshine days in July:
11.2 days - Average sunshine days in August:
10.8 days - Average sunshine days in September:
13.9 days - Average sunshine days in October:
19.5 days - Average sunshine days in November:
19.4 days - Average sunshine days in December:
19.1 days
The month with the most sunshine days is October (19.5 days).
The month with the least sunshine days is August (10.8 days).
Average UV index
Portsmouth, VA
The months with the highest UV index are July and August (UV index 7).
The month with the lowest UV index is January (UV index 2).
Average cloud cover
Portsmouth, VA
The month with the most cloud cover is March (Cloud cover 44).
The month with the least cloud cover is July (Cloud cover 26).
Average visibility
Portsmouth, VA
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
