Castlebar Weather in December
December in Castlebar averages 9°C (48°F) during the day and 4°C (39°F) at night. It is the wettest month of the year, with 122 mm (4.8 in) of rainfall on average, so waterproof gear is a must.
Rainfall in Castlebar in December
With this being the wettest month, keeping an umbrella on hand might save you from getting wet from a sudden shower. Typically, about 23 days will experience rainfall, with an average of 122 mm (4.8 in) for the month. This is a wet month with frequent and often heavy showers. Both the number of rain days and the total rainfall are high.
Temperature in Castlebar in December
Daytime temperatures in Castlebar reach 9°C (48°F) in December, dropping to 4°C (39°F) at night. December is typically considered a winter month. The days stay cool from start to finish. Layering up well will make outdoor time much more comfortable. At 4°C (39°F) overnight, it gets properly cold after dark. On the bright side, cold nights tend to make for excellent sleeping conditions.
Sunshine in Castlebar in December
The area experiences limited sunny days, amounting to roughly 35 hours of sunshine. This makes it perfect for those who lean towards cooler, cloudier settings rather than intense sunlit days.If you prefer dry days with pleasant temperatures, December may not be the ideal month to visit Castlebar. Our weather planner can help you explore destinations with more pleasant weather conditions.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Ireland, check out our Castlebar's climate page.
Castlebar Temperature in December
Min Temperature
4°C (39°F)
Max Temperature
9°C (48°F)
Chance of Rain
77%
Precipitation
122 mm (4.8 in)
Rainy days
23 days
Humidity
90% *
Sunshine
35 hours *
Percentage Sunshine
17% *
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Castlebar typically stay consistent throughout December, with daily highs averaging around 9°C (48°F). Nights are cold, with lows around 3°C (37°F).
Average temperatures in December
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 December
Historical weather for Castlebar in December
Browse day-by-day weather records for Castlebar spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Castlebar historical weather extremes in December
Based on weather observations in Castlebar between 1976 and 2025, these are the recorded extremes during December.
- The hottest December day on record in Castlebar reached 14°C (57°F) (December 9, 2025).
- Castlebar experienced its chilliest December day on December 20, 2010, reaching only -4°C (25°F).
- The lowest overnight temperature recorded in December was -13°C (9°F) (December 24, 2010).
- The wettest December day on record brought 68 mm (2.7 in) of precipitation to Castlebar (December 5, 2015).
Best Places in Ireland in December
Find out more about the weather in Ireland and which places have the best travel conditions in this month. See all of Ireland in December →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in Castlebar in December
We recommend to layer up for chilly conditions in Castlebar in December. You could start with thermal underwear or a good base layer to keep your core warm on the cooler days this month. Maybe also add a sweater or fleece, and top it off with a windproof jacket. High rain levels are expected, so pack waterproof gear and an umbrella or poncho. You can probably leave your sunglasses at home, because sunny days are pretty rare this month.What To Do in Castlebar in December
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Ireland, check out our Castlebar's climate page.
Temperature Rainfall Sunshine Humidity
See the full Castlebar climate overview or explore weather in Ireland.
