May Weather in Portsmouth, United States

Last updated: June 24, 2025

In Portsmouth, United States, the average temperature in May hovers around 19°C (66°F), creating a pleasant atmosphere for outdoor activities. However, temperatures can vary significantly, with minimums dropping to 1°C (34°F) and maximums soaring up to 32°C (90°F). Expect about 128 mm (5.0 in) of precipitation spread across 14 days, contributing to an average humidity of 81%—perfect for those who enjoy a lush, green environment!

May Temperature in Portsmouth

In May in Portsmouth, the average temperature is 19°C (66°F). Maximums can reach 32°C (90°F) and minimums can be as low as 1°C (34°F). This variation means that travelers should pack a range of clothing to accommodate both warm days and cooler nights.

May Weather in Portsmouth: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Portsmouth, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Portsmouth, May typically has an average temperature of 19°C (66°F), with highs reaching up to 32°C (90°F) and lows dropping to around 1°C (34°F).

Data source: Temperature data for Portsmouth generated using information from the Copernicus Climate Change Service.

May Precipitation in Portsmouth

In Portsmouth in May, the precipitation amount is 128 mm (5.0 in) over a span of 14 days.

May Precipitation Trends in Portsmouth

The chart displays monthly precipitation patterns in Portsmouth, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Portsmouth, May typically receives around 128 mm (5.0 inches) of precipitation spread over approximately 14 days.

Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

May Humidity in Portsmouth

In Portsmouth in May, humidity is 81%. With an average temperature of 19°C (66°F), this humidity feels like a warm, heavy blanket enveloping you, making travel feel both muggy and slightly stifling, often leading to a need for frequent breaks in the shade.

May Average Humidity in Portsmouth

This chart illustrates the average monthly humidity levels in Portsmouth, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Portsmouth is approximately 81%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Portsmouth

In Portsmouth in May, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Portsmouth.

Maximum UV Index Levels in Portsmouth for May

The chart shows the monthly maximum UV Index (UVI) for Portsmouth in May, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In May, the maximum UV index in Portsmouth typically reaches 10, which falls under the very high exposure category.

Data source: Portsmouth May UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How May Weather in Portsmouth Compares to Other Months

Weather in Portsmouth varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Portsmouth, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Portsmouth, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	2°C (35°F)	85 mm (3.3 inches)	88%	moderate
February Weather	4°C (39°F)	124 mm (4.9 inches)	88%	moderate
March Weather	8°C (47°F)	106 mm (4.2 inches)	87%	high
April Weather	13°C (55°F)	128 mm (5.0 inches)	85%	very high
May Weather	19°C (66°F)	128 mm (5.0 inches)	81%	very high
June Weather	23°C (73°F)	157 mm (6.2 inches)	82%	very high
July Weather	25°C (78°F)	107 mm (4.2 inches)	81%	very high
August Weather	24°C (75°F)	120 mm (4.7 inches)	73%	very high
September Weather	21°C (71°F)	109 mm (4.3 inches)	73%	very high
October Weather	15°C (60°F)	116 mm (4.5 inches)	78%	high
November Weather	7°C (45°F)	77 mm (3.0 inches)	89%	moderate
December Weather	4°C (40°F)	112 mm (4.4 inches)	87%	moderate