Castletown, United Kingdom — Weather in September 2026

Climate Overview

Castletown, United Kingdom in September has mild conditions, with highs averaging 14.4°C (58°F) and noticeably cooler mornings. Rain falls on about 17 days this month, totalling around 91 mm. Winds are noticeable. Sea temperature stays cool at 13.8°C (57°F).

This month falls at the beginning of Autumn.

Daily highs in September gradually drop from around 16°C (60°F) at the start to 13°C (56°F) by month's end.

September sees fairly even rainfall, totalling about 91 mm across the month.

Expect around 8.8h of sunshine at the start of September, decreasing to 7.1h by the end.

Wind speeds pick up through the month, from 24 km/h (15 mph) to 29 km/h (18 mph).

The warmest days tend to fall around the 1th, averaging 15.8°C (60°F).

Compared to August, this month is about 1°C cooler with 2 more rainy days. Temperatures begin dropping heading into October.

Monthly September Averages

Temperature

14°C / 11°C

Feels Like

12°C / 8°C

Rain

17 days · 91 mm

Sunshine

7.8h / day

Humidity

81% — Very Humid

Wind

26 km/h

Wind Direction

SSW (210°)

Gusts

48 km/h

Daylight

12.8 h

Cloud Cover

72%

Clear Sky Days

0.6

UV Index

3.1 — Moderate

Sea Temperature

14°C

Dew Point

9°C — Dry

Moon Phase

Waxing Crescent · 11%

Climate Charts

Daily averages based on historical data (2016–2025)

Daily Temperature

High Low

Daily Precipitation

Rainfall

Daily Sunshine

Sunshine

Daily Wind Speed

Wind Speed

Sun Position

Sunrise 06:43

Daylight 12.8h

Sunset 19:34

What to Expect

Keep afternoons flexible as tropical showers are common — they typically clear within an hour.

Wet weather can spread across much of the day, so it is best to keep outdoor plans flexible.

1 of the last 5 yearly records were warmer than this month's long-run average.

Compare Months

Month	Temp	Feels Like	Rain	Sun	Humidity	UV	Status	Details
January	7°C / 4°C	2°C / -2°C	15days (69 mm) Wet	2.9h Poor	79% Humid	0.6 Low	Poor	View Details
February	7°C / 3°C	2°C / -2°C	14days (59 mm) Wet	5.3h Fair	78% Humid	1.2 Low	Poor	View Details
March	8°C / 4°C	3°C / -1°C	15days (58 mm) Wet	7.2h Good	78% Humid	2.6 Moderate	Poor	View Details
April	9°C / 5°C	5°C / 1°C	13days (53 mm) Wet	9.8h Good	77% Humid	3.9 Moderate	Poor	View Details
May best	12°C / 7°C	9°C / 4°C	14days (59 mm) Wet	10.7h Excellent	80% Humid	5 Moderate	Fair	View Details
June best	14°C / 10°C	12°C / 7°C	14days (66 mm) Wet	11.2h Excellent	81% Humid	5.2 High	Fair	View Details
July best	16°C / 12°C	14°C / 9°C	17days (83 mm) Wet	10h Excellent	83% Humid	4.8 Moderate	Good	View Details
August best	16°C / 12°C	14°C / 10°C	15days (75 mm) Wet	9.8h Good	82% Humid	4.4 Moderate	Good	View Details
September	14°C / 11°C	12°C / 8°C	17days (91 mm) Wet	7.8h Good	81% Humid	3.1 Moderate	Fair	View Details
October	12°C / 9°C	8°C / 5°C	17days (95 mm) Wet	5.2h Fair	80% Humid	1.5 Low	Poor	View Details
November	9°C / 6°C	5°C / 1°C	16days (77 mm) Wet	3.4h Poor	80% Humid	0.7 Low	Poor	View Details
December	8°C / 5°C	3°C / 0°C	16days (83 mm) Wet	2.1h Poor	82% Humid	0.4 Low	Poor	View Details

What to Wear

Bundle up with a warm coat, scarf, and closed-toe shoes. Thermal layers underneath give flexibility between indoors and outdoors.

A waterproof jacket or compact umbrella is recommended for occasional showers.

Packing List

Layered clothingLight jacketUmbrellaWaterproof jacketWaterproof shoes

Frequently Asked Questions

Expand all

Is September a good time to visit Castletown?

September is typically fair for visiting Castletown, with average highs of 14°C (58°F) and around 17 rainy days. Castletown, United Kingdom in September has mild conditions, with highs averaging 14.4°C (58°F) and noticeably cooler mo

Does it rain a lot in Castletown in September?

Castletown typically sees around 17 rainy days in September with 91 mm (3.6 in) of total rainfall. Pack a waterproof jacket.

Does it get cold at night in Castletown in September?

Nights in Castletown during September are cool at around 11°C (51°F). Bring a jacket or sweater for evenings.

What should I pack for Castletown in September?

With highs of 14°C (58°F) and lows of 11°C (51°F) in September, we recommend: Layered clothing, Light jacket, Umbrella, Waterproof jacket, Waterproof shoes. Comfortable walking shoes are essential.

Is September among the best months weather-wise in Castletown?

September is not the most favourable month weather-wise in Castletown. Consider visiting during months with milder temperatures or less rainfall for a better experience.

What is the UV index in Castletown in September?

The average UV index in Castletown during September is 3 (moderate). Sunscreen and sunglasses are recommended during midday hours.

How many hours of daylight are there in Castletown in September?

Castletown gets approximately 13 hours of daylight per day in September, with around 8 hours of sunshine.

Does it snow in Castletown in September?

Snow is uncommon in Castletown during September based on 10-year climate averages.

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