Union Island weather in September 2025

Q: How hot is it in Union Island in September?

Daytime temperatures usually reach 30°C in Union Island in September with very high heat and humidity, falling to 23°C at night.

Q: How sunny is it in Union Island in September?

There are normally 7 hours of bright sunshine each day in Union Island in September - that's 60% of daylight hours.

Q: How warm is the sea around Union Island in September?

The average sea temperature around Union Island in September is 29°C.

Q: Does it rain in Union Island in September?

There are usually 21 days with some rain in Union Island in September and the average monthly rainfall is 186mm.

Q: What is the chance of a cyclone in Union Island in September?

On average less than 1 day in September in Union Island is likely to be affected by the passage of one or more tropical storms.

Expect 30°C daytime maximum temperatures in the shade with on average 7 hours of sunshine per day in Union Island in September. Check more long-term weather averages for Union Island in September before you book your next holiday to St Vincent & the Grenadines in 2025/2026.

30
30°C max day temperature
7
7 hours of sunshine per day
21
21 days with some rainfall
23
23°C min night temperature
12
12 hours of daylight per day
VH
Very High heat & humidity
186
186 mm of monthly rainfall
11
11+ (Extreme) UV index
29
29°C sea temperature

More about Union Island

Union Island by month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Recommended for St Vincent & the Grenadines

Travel Up: up to £20 off flight & hotel bookings

Discount Code

Save up to £20 on flights & hotels with Travel Up
Offer only valid on bookings of £500 or more
Use discount code at check out for offer to apply

Show discount code

******M20

Redeem Travel Up discount code >>

Expires at 23:59 on Saturday 30th Nov 2024 · View all Travel Up offers

The September weather guide for St Vincent & the Grenadines (Union Island) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm) | Imperial (°F / inches)

More about St Vincent & the Grenadines

How hot is it in Union Island in September?

Daytime temperatures usually reach 30°C in Union Island in September with very high heat and humidity, falling to 23°C at night.

How sunny is it in Union Island in September?

There are normally 7 hours of bright sunshine each day in Union Island in September - that's 60% of daylight hours.

How warm is the sea around Union Island in September?

The average sea temperature around Union Island in September is 29°C.

Does it rain in Union Island in September?

There are usually 21 days with some rain in Union Island in September and the average monthly rainfall is 186mm.

What is the chance of a hurricane in Union Island in September?

On average less than 1 day in September in Union Island is likely to be affected by the passage of one or more tropical storms.

Union Island September sunrise & sunset times

Browse the sunrise and sunset times for Union Island in September 2025. Select a month to view Union Island sunrise and sunset times for the next 12 months.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Date	Sunrise times	Sunset times
Monday, 1st September 2025	05:55	18:16
Monday, 15th September 2025	05:55	18:06
Tuesday, 30th September 2025	05:55	17:56

Be inspired

Get your weekly fix of holiday inspiration from some of the world's best travel writers plus save on your next trip with the latest exclusive offers

We promise not to share your details

Popular travel offers

St Vincent and the Grenadines - quick facts
Flight time^✝	11 hours
Time difference	UK -4 hours
Language(s)	English
Currency	Eastern Caribbean Dollar
Electricity	A + B + G plug (110V)
Driving side	Left
Why visit?	Beaches Nature
Tourist info	St. Vincent & the Grenadines Tourism Authority