Portstewart Strand — Sea temperature now
Northern Ireland family beach.
Fresh water with a light chop and a light breeze — fresh conditions — a wetsuit is recommended.
Location
Portstewart Strand on the map, with nearby beaches and live sea temperatures.
7-day forecast
Water, air, waves, wind and UV outlook for the week ahead.
Monthly sea temperature averages
Typical year-round water temperature, based on regional climatology.
Best time to swim in Portstewart Strand
The sea in Portstewart Strand peaks in August, when the water averages around 17°C.
On average, 0 months a year sit above 20°C — the threshold most swimmers describe as pleasant without a wetsuit.
Outside peak season the water drops toward 9°C, so a 3/2mm shorty or full wetsuit makes long swims much more comfortable.
The coldest month is typically February at around 8°C, when cold-water swimmers dominate the coast.
Portstewart Strand sea temperature history
Long-term climatology for Portstewart Strand shows an annual mean sea temperature of 12°C, ranging from 8°C in winter to 17°C at the summer peak.
The seasonal swing is roughly 9°C between the coldest and warmest month — a useful yardstick when comparing years or checking whether the current sea is running above or below average.
Recent decades have trended slightly warmer at Portstewart Strand, in line with regional sea-surface temperature records for the wider basin.
Monthly averages below are drawn from multi-decadal climatology and are updated as new observations arrive.
Portstewart Strand sea temperature: frequently asked questions
What is the warmest month to swim in Portstewart Strand?
August is the warmest month in Portstewart Strand, when the sea averages about 17°C. Late-season warmth often persists a few weeks after peak.
When is the sea coldest in Portstewart Strand?
The coldest month in Portstewart Strand is typically February, when the water averages around 8°C. Cold-water swimmers and surfers dominate this period.
When can you swim in Portstewart Strand without a wetsuit?
The sea in Portstewart Strand rarely climbs above 20°C, so a wetsuit is recommended year-round for anything longer than a quick dip.
Do I need a wetsuit in Portstewart Strand?
Outside peak summer the water in Portstewart Strand drops toward 9°C, so a 3/2mm shorty or full wetsuit makes long swims much more comfortable. In peak months most swimmers go without.
What is the average sea temperature in Portstewart Strand?
The long-term annual mean sea temperature in Portstewart Strand is about 12°C, based on multi-decadal climatology of the surrounding waters.
How do I check the current sea temperature in Portstewart Strand?
The live reading at the top of this page shows the current sea temperature in Portstewart Strand, updated hourly from marine buoy and satellite data. The 7-day forecast covers water, air, waves, wind and UV for the week ahead.
Year-round sea temperature
| Month | Sea | Comfort |
|---|---|---|
| Jan | 9°C | Cold |
| Feb | 8°C | Cold |
| Mar | 8°C | Cold |
| Apr | 9°C | Cold |
| May | 11°C | Cold |
| Jun | 14°C | Bracing |
| Jul | 16°C | Bracing |
| Aug ⭐ | 17°C | Bracing |
| Sep | 16°C | Bracing |
| Oct | 14°C | Bracing |
| Nov | 12°C | Cold |
| Dec | 10°C | Cold |