Dundalk Weather in September
During September, Dundalk experiences moderate daytime temperatures of 18°C (64°F) and cooler nights around 10°C (50°F). Expect quite a bit of rainfall. Around 76 mm (3 in) is typical.
Rainfall in Dundalk in September
On average, there are about 17 days with rain during this month, averaging 76 mm (3 in). Rain is frequent but mostly light this month, with brief showers more common than heavy downpours.
Temperature in Dundalk in September
September in Dundalk sees highs of 18°C (64°F) and lows of 10°C (50°F) overnight. Conditions are often most pleasant around the middle of the day. Nights drop to around 10°C (50°F), which is noticeably cooler than the daytime. A light jacket for the evening is a sensible addition, and the cool nights tend to make sleeping comfortable.
Sunshine in Dundalk in September
The city usually sees around 128 hours of sunlight, indicating a moderately sunny period.For Dundalk itself, July generally stands out with the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.
Dundalk Temperature in September
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Dundalk Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Dundalk - and find the best time to visit.
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Dundalk typically stay consistent throughout September, with daily highs averaging around 18°C (64°F). Nights are cool, with lows typically ranging from 9°C (48°F) to 11°C (52°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather records for Dundalk in September
Browse day-by-day weather records for Dundalk spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Dundalk historical weather extremes in September
Based on 49 years of weather observations in Dundalk between 1976 and 2025, these are the recorded extremes.
- Dundalk recorded its highest September temperature of 25°C (77°F) on September 5, 2023.
- On September 24, 2012, Dundalk saw its coldest September day with temperatures maxing out at 10°C (50°F).
- The lowest overnight temperature recorded in September was 2°C (36°F) (September 30, 1991).
- Peak precipitation in September occurred on September 6, 2010, when 51 mm (2 in) of precipitation was measured.
Best Places in Ireland in September
Find out more about the weather in Ireland and which places have the best travel conditions in this month. See all of Ireland in September →
Perfect weather is subjective. On this map perfect weather has been defined with temperatures between 20°C (68°F) and 29°C (84°F) and not too much precipitation (less than 90 mm (3.5 in) a month).
What to Wear in Dundalk in September
For Dundalk in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. Rain is likely on several days, so bring a good rain jacket. It won't hurt to bring your sunglasses along, as you'll see some sunny periods.
What To Do in Dundalk in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
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Swimming6/10 -
Cycling6/10 -
Walking6/10 -
Camping8/10 -
Outdoor sports9/10
Dundalk 3-Day Forecast
Temperature Rainfall Sunshine Humidity
See the full Dundalk climate overview or explore weather in Ireland.
Popular in September
Where to go in September - average daytime high across popular destinations.
Westport
17°C (63°F) Doolin17°C (63°F) Kilkenny
18°C (64°F) Cork18°C (64°F) Kenmare18°C (64°F) Killarney17°C (63°F) Galway18°C (64°F) Dublin18°C (64°F) 
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