Last updated: August 27, 2025
In September, the average temperature in Castletown, United Kingdom hovers around 13°C (55°F). Expect a cool minimum of 3°C (37°F) and a pleasant max of 23°C (74°F). Be prepared for some rain, as 109 mm (4.3 in) of precipitation typically falls over 17 days. With an average humidity of 88%, you might want to pack an umbrella and dress in layers!
In September, in Castletown, the average temperature is 13°C (55°F). The maximum can reach 23°C (74°F) and the minimum can be as low as 3°C (37°F). It's advisable to pack layers to accommodate fluctuating temperatures during your travels.
In Castletown in September, the precipitation amount is 109 mm (4.3 in), occurring over the course of 17 days.
In Castletown in September humidity is 88%. With an average temperature of 13°C (55°F), this humidity feels like a damp chill that clings to your skin, making it essential to dress in layers while exploring, as the moisture in the air can lead to a rather uncomfortable experience for traveling.
In Castletown in September, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Castletown for better planning.
UV Risk Categories
Weather in Castletown varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Castletown, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 5°C (42°F) | 57 mm (2.2 inches) | 82% | low |
| February Weather | 5°C (42°F) | 62 mm (2.5 inches) | 81% | low |
| March Weather | 6°C (43°F) | 72 mm (2.8 inches) | 81% | moderate |
| April Weather | 7°C (45°F) | 55 mm (2.2 inches) | 81% | moderate |
| May Weather | 10°C (50°F) | 67 mm (2.6 inches) | 83% | moderate |
| June Weather | 13°C (55°F) | 70 mm (2.8 inches) | 84% | high |
| July Weather | 14°C (58°F) | 74 mm (2.9 inches) | 87% | high |
| August Weather | 14°C (58°F) | 79 mm (3.1 inches) | 86% | high |
| September Weather | 13°C (55°F) | 109 mm (4.3 inches) | 88% | moderate |
| October Weather | 10°C (51°F) | 112 mm (4.4 inches) | 87% | moderate |
| November Weather | 8°C (46°F) | 92 mm (3.6 inches) | 87% | low |
| December Weather | 6°C (43°F) | 71 mm (2.8 inches) | 80% | low |