Dorchester, United States — Weather in September 2026

Monthly climate averages for Dorchester, United States. Based on 10-year ERA5 reanalysis data.

Cfa Humid Subtropical
8.6 /10
Excellent

September is an excellent month in Dorchester

Climate Overview

Dorchester, United States in September has warm conditions, with highs averaging 22.7°C (73°F). Sea temperature stays cool at 19.1°C (66°F).

This month falls at the beginning of Autumn.

Daily highs in September gradually drop from around 24°C (76°F) at the start to 21°C (69°F) by month's end.

Rainfall is heaviest during the first third of the month, while the middle tends to be drier.

Expect around 9.7h of sunshine at the start of September, decreasing to 7.8h by the end.

The warmest days tend to fall around the 5th, averaging 24.9°C (77°F).

Compared to August, this month is about 4°C cooler with 1 fewer rainy days. Temperatures begin dropping heading into October.

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Monthly September Averages

Temperature
23°C / 16°C
Feels Like
23°C / 15°C
Rain
9 days · 91 mm
Sunshine
8.5h / day
Humidity
77% — Humid
Wind
18 km/h
Wind Direction
WNW (283°)
Gusts
36 km/h
Daylight
12.5 h
Cloud Cover
57%
Clear Sky Days
6.1
UV Index
5.1 — High
Sea Temperature
19°C
Dew Point
15°C — Comfortable
Moon Phase
Waxing Crescent · 11%

Climate Charts

Daily averages based on historical data (2016–2025)

Daily Temperature

32°C 28°C 24°C 20°C 16°C 12°C 8°C 151015202530
High Low

Daily Precipitation

0 mm 2 mm 4 mm 6 mm 8 mm 151015202530
Rainfall

Daily Sunshine

0h 3h 6h 9h 12h 151015202530
Sunshine

Daily Wind Speed

0 6 12 18 24 30 151015202530
Wind Speed
Sun Position
Sunrise 06:24
Daylight 12.5h
Sunset 18:54

What to Expect

Daytime temperatures around 23°C (73°F) are ideal for full-day outdoor exploration.

Rain usually comes in shorter passing showers rather than all-day rain.

Recent yearly records for September have stayed close to the long-run average.

Compare Months

January
Poor
Temp
3°C / -4°C
Feels Like
-2°C / -9°C
Rain
10days (103 mm) Wet
Sun
5.9h Fair
Humidity
68% Muggy
UV
2.3 Moderate
Snow Days
8days
View Details
February
Poor
Temp
5°C / -3°C
Feels Like
0°C / -9°C
Rain
10days (90 mm) Wet
Sun
6.6h Fair
Humidity
70% Muggy
UV
3.3 Moderate
Snow Days
8days
View Details
March
Poor
Temp
8°C / 0°C
Feels Like
4°C / -5°C
Rain
11days (108 mm) Wet
Sun
7.8h Good
Humidity
67% Muggy
UV
4.3 Moderate
Snow Days
4days
View Details
April
Fair
Temp
13°C / 5°C
Feels Like
11°C / 1°C
Rain
11days (109 mm) Wet
Sun
8.4h Good
Humidity
70% Muggy
UV
5.2 High
Snow Days
2days
View Details
May
Good
Temp
19°C / 10°C
Feels Like
18°C / 8°C
Rain
11days (86 mm) Wet
Sun
9.7h Good
Humidity
73% Muggy
UV
6.3 High
View Details
June best
Excellent
Temp
24°C / 16°C
Feels Like
25°C / 15°C
Rain
10days (71 mm) Wet
Sun
11h Excellent
Humidity
73% Muggy
UV
6.8 High
View Details
July best
Excellent
Temp
28°C / 20°C
Feels Like
30°C / 21°C
Rain
10days (94 mm) Wet
Sun
11.1h Excellent
Humidity
75% Muggy
UV
7 High
View Details
August best
Excellent
Temp
27°C / 19°C
Feels Like
29°C / 20°C
Rain
10days (70 mm) Wet
Sun
10.7h Excellent
Humidity
74% Muggy
UV
6.5 High
View Details
September best
Excellent
Temp
23°C / 16°C
Feels Like
23°C / 15°C
Rain
9days (91 mm) Wet
Sun
8.5h Good
Humidity
77% Humid
UV
5.1 High
View Details
October best
Good
Temp
17°C / 10°C
Feels Like
15°C / 8°C
Rain
9days (113 mm) Wet
Sun
7h Good
Humidity
76% Humid
UV
3.8 Moderate
View Details
November
Poor
Temp
11°C / 3°C
Feels Like
7°C / -1°C
Rain
9days (78 mm) Wet
Sun
6.5h Fair
Humidity
71% Muggy
UV
2.6 Moderate
Snow Days
1days
View Details
December
Poor
Temp
5°C / -2°C
Feels Like
1°C / -7°C
Rain
11days (121 mm) Wet
Sun
5.5h Fair
Humidity
71% Muggy
UV
1.9 Low
Snow Days
6days
View Details
Month Temp Feels Like Rain Sun Humidity UV Status
January 3°C / -4°C -2°C / -9°C 10days (103 mm) Wet 5.9h Fair 68% Muggy 2.3 Moderate Poor View Details
February 5°C / -3°C 0°C / -9°C 10days (90 mm) Wet 6.6h Fair 70% Muggy 3.3 Moderate Poor View Details
March 8°C / 0°C 4°C / -5°C 11days (108 mm) Wet 7.8h Good 67% Muggy 4.3 Moderate Poor View Details
April 13°C / 5°C 11°C / 1°C 11days (109 mm) Wet 8.4h Good 70% Muggy 5.2 High Fair View Details
May 19°C / 10°C 18°C / 8°C 11days (86 mm) Wet 9.7h Good 73% Muggy 6.3 High Good View Details
June best 24°C / 16°C 25°C / 15°C 10days (71 mm) Wet 11h Excellent 73% Muggy 6.8 High Excellent View Details
July best 28°C / 20°C 30°C / 21°C 10days (94 mm) Wet 11.1h Excellent 75% Muggy 7 High Excellent View Details
August best 27°C / 19°C 29°C / 20°C 10days (70 mm) Wet 10.7h Excellent 74% Muggy 6.5 High Excellent View Details
September best 23°C / 16°C 23°C / 15°C 9days (91 mm) Wet 8.5h Good 77% Humid 5.1 High Excellent View Details
October best 17°C / 10°C 15°C / 8°C 9days (113 mm) Wet 7h Good 76% Humid 3.8 Moderate Good View Details
November 11°C / 3°C 7°C / -1°C 9days (78 mm) Wet 6.5h Fair 71% Muggy 2.6 Moderate Poor View Details
December 5°C / -2°C 1°C / -7°C 11days (121 mm) Wet 5.5h Fair 71% Muggy 1.9 Low Poor View Details

What to Wear

Dress in layers — a mix of long sleeves, light sweaters, and a versatile jacket works best for changeable conditions.

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

Packing List

UmbrellaSunscreen (SPF 30+)SunglassesComfortable walking shoes

Frequently Asked Questions

September is typically excellent for visiting Dorchester, with average highs of 23°C (73°F) and around 9 rainy days. Dorchester, United States in September has warm conditions, with highs averaging 22.7°C (73°F). Sea temperature stays co
Dorchester typically sees around 9 rainy days in September with 91 mm (3.6 in) of total rainfall. An umbrella should suffice.
Evenings in Dorchester during September are mild at 16°C (60°F). A light cardigan is usually enough.
With highs of 23°C (73°F) and lows of 16°C (60°F) in September, we recommend: Umbrella, Sunscreen (SPF 30+), Sunglasses, Comfortable walking shoes. Comfortable walking shoes are essential.
Yes, September offers some of the best weather conditions in Dorchester with comfortable temperatures and lower chances of rain.
The average UV index in Dorchester during September is 5 (moderate). Sunscreen and sunglasses are recommended during midday hours.
Dorchester gets approximately 13 hours of daylight per day in September, with around 9 hours of sunshine.
Snow is uncommon in Dorchester during September based on 10-year climate averages.

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