Portmarnock Weather in September

September in Portmarnock brings moderate temperatures, with highs of 17°C (63°F) and nights dropping to 12°C (54°F). Rainfall is on the higher side this month, averaging around 78 mm (3.1 in), so keep a rain jacket handy.

Rainfall in Portmarnock in September

The climate data from previous years indicates about 15 days of rain, averaging 78 mm (3.1 in) for the month. The rainfall pattern this month is fairly balanced. Showers tend to be moderate rather than extreme.

Temperature in Portmarnock in September

If you're visiting Portmarnock in September, expect highs of 17°C (63°F) and overnight lows around 12°C (54°F). During September, you'll experience the summer season. Even when the weather is stable, mornings and evenings can still feel distinctly cool. At 12°C (54°F) overnight, it can feel quite a bit cooler after dark. Worth packing something warmer for evenings, but the cooler temperatures are ideal for sleeping.

Sunshine in Portmarnock in September

The month experiences a moderate amount of sunlight, with 128 hours of sunshine. This provides a nice balance between sunshine and clouds.

Wind Speed in Portmarnock in September

Wind speeds average 4 m/s (8 knots) during September. At this speed, expect moderate winds that can raise dust and move small branches. Since this is an average, some days have gentle light winds while others experience stronger breezes that are quite noticeable.

Average water temperature in September

With water at 15°C (59°F), it's on the cooler side. Keen swimmers won't be put off, but those who prefer warm water may find it less enjoyable.

Our weather planner can help you find worldwide destinations with pleasant weather during this period. July and August typically offer the best weather for Portmarnock.

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For a detailed overview over the year and the best time to visit Ireland, check out our Portmarnock's climate page.

Portmarnock Temperature in September

Min Temperature 12°C (54°F)  

Max Temperature 17°C (63°F)  

Water Temperature 15°C (59°F) *  

Chance of Rain 50%  

Precipitation 78 mm (3.1 in)  

Rainy days 15 days  

Humidity 71% *  

Windspeed 4 m/s (8 knots) *  

Sunshine 128 hours *  

Percentage Sunshine 33% *  

* Data from: Dublin, Ireland (7 KM, 4 Miles).

What to Wear in Portmarnock in September

Comfortable temperatures call for an easy wardrobe in September. Pack summer basics like t-shirts and shorts, but include a light jacket for cooler moments. A pair of comfortable walking shoes is essential. Wet weather is likely, so pack waterproof gear for multiple rainy days. With water temperatures around 15°C (59°F), the water is quite cold for swimming. You can skip the swimwear unless you're particularly tough. It won't hurt to bring your sunglasses along, as you'll see some sunny periods.

What To Do in Portmarnock in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

6/10

Cycling

6/10

Walking

6/10

Camping

8/10

Outdoor sports

9/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Ireland, check out our Portmarnock's climate page.

More climate data for Portmarnock

Temperature Rainfall Sunshine Humidity Wind Speed Water Temp

See the full Portmarnock climate overview or explore weather in Ireland.