May Weather in Belfast, United States

Last updated: June 24, 2025

In May, the average temperature in Belfast, United States is a mild 11°C (53°F). However, temperatures can vary significantly, with a minimum of 1°C (34°F) and a maximum soaring to 30°C (87°F). Expect 90 mm (3.6 in) of precipitation spread over 10 days, and enjoy a relatively high average humidity of 76%.

May Temperature in Belfast

In May in Belfast, the average temperature is 11°C (53°F). Maximum temperatures can reach 30°C (87°F), while minimum temperatures can drop as low as 1°C (34°F). This range makes it a great time to plan for outdoor adventures, so be sure to pack both light and warm clothing for your travels.

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

The chart illustrates May temperature patterns in Belfast, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Belfast, May typically has an average temperature of 11°C (53°F), with highs reaching up to 30°C (87°F) and lows dropping to around 1°C (34°F).

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

May Precipitation in Belfast

In Belfast in May, the precipitation amount is 90 mm (3.6 in) spread over the course of 10 days.

May Precipitation Trends in Belfast

The chart displays monthly precipitation patterns in Belfast, 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 Belfast, May typically receives around 90 mm (3.6 inches) of precipitation spread over approximately 10 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

May Humidity in Belfast

In Belfast in May, humidity is 76%. With an average temperature of 11°C (53°F), this humidity feels like a brisk chill that can make outdoor excursions slightly uncomfortable, as the dampness in the air clings to your skin, making layered clothing essential for any travelers venturing out.

May Average Humidity in Belfast

This chart illustrates the average monthly humidity levels in Belfast, 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 Belfast is approximately 76%, 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 Belfast

In Belfast in May, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Belfast.

Maximum UV Index Levels in Belfast for May

The chart shows the monthly maximum UV Index (UVI) for Belfast 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 Belfast typically reaches 9, which falls under the very high exposure category.

Data source: Belfast 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 Belfast Compares to Other Months

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

This table compares monthly weather conditions in Belfast, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-4°C (24°F)	93 mm (3.7 inches)	88%	low
February Weather	-4°C (26°F)	88 mm (3.5 inches)	88%	moderate
March Weather	0°C (32°F)	72 mm (2.9 inches)	85%	moderate
April Weather	6°C (43°F)	131 mm (5.2 inches)	81%	high
May Weather	11°C (53°F)	90 mm (3.6 inches)	76%	very high
June Weather	17°C (63°F)	76 mm (3.0 inches)	74%	very high
July Weather	20°C (68°F)	91 mm (3.6 inches)	74%	very high
August Weather	20°C (68°F)	75 mm (3.0 inches)	74%	very high
September Weather	16°C (61°F)	77 mm (3.0 inches)	77%	high
October Weather	11°C (51°F)	130 mm (5.1 inches)	82%	moderate
November Weather	3°C (38°F)	121 mm (4.8 inches)	85%	moderate
December Weather	-2°C (28°F)	129 mm (5.1 inches)	84%	low