Portstewart Temperature by Month

Portstewart in Londonderry County, United Kingdom sees moderate seasonal temperature shifts, with daytime highs between 9°C (48°F) in February and 17°C (63°F) in August, averaging 13°C (55°F) annually. Explore the full monthly breakdown below.

The moderate changes in the climate in Portstewart ensure gradual weather shifts through each season. At night, temperatures drop to between 13°C (55°F) and 5°C (41°F) depending on the time of year.

The chart below illustrates the average maximum day and minimum night temperatures in Portstewart by month:

Temperatures tend to bottom out between 4 AM and 6 AM, then climb to their daily peak around 3 PM. August, the warmest month, sees 140 hours of sunshine.

The chart below shows the average temperature throughout the year:

Portstewart's average annual maximum temperature is 13°C (55°F). To put that in context, here's how it compares to a few well-known destinations:

Rome, Italy averages 20°C (68°F) annually, with reliably warm summers and comfortable winters.

Toronto, Canada averages 13°C (55°F) annually, with cold snowy winters balanced by genuinely warm summers.

Seoul, South Korea averages 18°C (64°F) a year, with four clear seasons, cold winters, and hot humid summers.

Adelaide, Australia averages 21°C (70°F) a year, with warm summers, mild winters, and relatively low rainfall year-round.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Whether a city sits on the coast or deep inland makes a significant difference to its climate. Coastal areas tend to have more stable temperatures year-round, large bodies of water absorb heat slowly in summer and release it gradually in winter, keeping extremes in check. Cities far from the sea don't benefit from that buffer, which is why continental climates tend to have hotter summers and colder winters than their coastal counterparts at the same latitude.

For more on Portstewart's weather, including monthly rainfall, sunshine hours, and humidity, visit our Portstewart climate page.