Last updated: August 23, 2025
In December, the average temperature in St Johnston, Ireland hovers around 6°C (43°F). Expect cool days where the temperature can dip to a minimum of -3°C (28°F), while occasionally reaching a high of 13°C (55°F). Be prepared for 103 mm (4.1 in) of precipitation spread over 19 days, coupled with a notable average humidity of 84%. Stay cozy and embrace the changing weather!
In December in St Johnston, the average temperature is 6°C (43°F), with maximums reaching 13°C (55°F) and minimums dropping as low as -3°C (28°F). Travelers should pack accordingly for chilly days and cold nights while exploring the area.
In St Johnston in December, the precipitation amount reaches 103 mm (4.1 in) over a period of 19 days.
In St Johnston in December, humidity is 84%. With an average temperature of 6°C (43°F), this humidity feels like a damp chill that penetrates your clothing, making outdoor excursions uncomfortable and prompting travelers to seek refuge indoors or find warm, sheltered spots to enjoy their surroundings.
In St Johnston in December, the maximum UV index is 1, which corresponds to a low Exposure Category. This means you have a time to burn of 45 minutes. For more details, you can check the Hourly UV Index in St Johnston.
UV Risk Categories
Weather in St Johnston varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in St Johnston, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 5°C (42°F) | 72 mm (2.8 inches) | 84% | low |
| February Weather | 6°C (42°F) | 113 mm (4.4 inches) | 84% | low |
| March Weather | 6°C (44°F) | 106 mm (4.2 inches) | 83% | moderate |
| April Weather | 8°C (47°F) | 64 mm (2.5 inches) | 84% | moderate |
| May Weather | 11°C (52°F) | 93 mm (3.7 inches) | 83% | high |
| June Weather | 13°C (56°F) | 107 mm (4.2 inches) | 83% | very high |
| July Weather | 15°C (59°F) | 99 mm (3.9 inches) | 86% | very high |
| August Weather | 15°C (58°F) | 157 mm (6.2 inches) | 86% | high |
| September Weather | 13°C (55°F) | 97 mm (3.8 inches) | 87% | moderate |
| October Weather | 10°C (50°F) | 112 mm (4.4 inches) | 87% | moderate |
| November Weather | 7°C (46°F) | 94 mm (3.7 inches) | 88% | low |
| December Weather | 6°C (43°F) | 103 mm (4.1 inches) | 84% | low |