Union Island weather live forecast

Today's maximum temperature in Union Island is expected to be 29°C. Select a day from the live weather forecast for Union Island, St Vincent & the Grenadines for more weather parameters.

• Thursday
  18th Sep
  29
  28
  
  6
  10
• Friday
  19th Sep
  28
  28
  
  5
  9
• Saturday
  20th Sep
  28
  28
  
  5
  11
• Sunday
  21st Sep
  28
  28
  
  6
  11
• Monday
  22nd Sep
  28
  28
  
  6
  11

5-day weather forecast updated at 04:01 on Thursday 18th September 2025 GMT

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The 5-day weather forecast for St Vincent & the Grenadines (Union Island) is provided by the Swiss meteorological agency, meteoblue. Find out more about our data sources.

Union Island weather forecast by day

Below are the detailed weather forecasts for Union Island for the next 5 days.

Union Island weather for Thursday 18th September 2025

Expect isolated thunderstorms in Union Island, St Vincent & the Grenadines with a maximum temperature of 29°C, moderate levels of heat & humidity, maximum UV of 10 (Very High) and 6 hours of bright sunshine. There are 0-2 mm of rainfall expected with 44% chance of some rain and a gentle breeze of 16 kph from the east.

• 29
  °C maximum temperature
• 28
  °C minimum temperature
• 
  isolated thunderstorms
• 6
  hours of sunshine
• 10
  UV index (Very High)
• 44
  % chance of some rain
• <2
  mm of rainfall expected
• M
  moderate heat & humidity
• 16
  kph wind from E

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Union Island weather for Friday 19th September 2025

Expect broken clouds in Union Island, St Vincent & the Grenadines with a maximum temperature of 28°C, moderate levels of heat & humidity, maximum UV of 9 (Very High) and 5 hours of bright sunshine. There are 0 mm of rainfall expected and a gentle breeze of 13 kph from the east.

• 28
  °C maximum temperature
• 28
  °C minimum temperature
• 
  broken clouds
• 5
  hours of sunshine
• 9
  UV index (Very High)
• 0
  mm of rainfall expected
• M
  moderate heat & humidity
• 13
  kph wind from E

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Union Island weather for Saturday 20th September 2025

Expect isolated thunderstorms in Union Island, St Vincent & the Grenadines with a maximum temperature of 28°C, moderate levels of heat & humidity, maximum UV of 11+ (Extreme) and 5 hours of bright sunshine. There are 5-10 mm of rainfall expected with 36% chance of some rain and a light breeze of 12 kph from the east.

• 28
  °C maximum temperature
• 28
  °C minimum temperature
• 
  isolated thunderstorms
• 5
  hours of sunshine
• 11
  UV index (Extreme)
• 36
  % chance of some rain
• <10
  mm of rainfall expected
• M
  moderate heat & humidity
• 12
  kph wind from E

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Union Island weather for Sunday 21st September 2025

Expect isolated thunderstorms in Union Island, St Vincent & the Grenadines with a maximum temperature of 28°C, moderate levels of heat & humidity, maximum UV of 11+ (Extreme) and 6 hours of bright sunshine. There are 2-5 mm of rainfall expected with 50% chance of some rain and a gentle breeze of 15 kph from the east.

• 28
  °C maximum temperature
• 28
  °C minimum temperature
• 
  isolated thunderstorms
• 6
  hours of sunshine
• 11
  UV index (Extreme)
• 50
  % chance of some rain
• <5
  mm of rainfall expected
• M
  moderate heat & humidity
• 15
  kph wind from E

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Union Island weather for Monday 22nd September 2025

Expect isolated thunderstorms in Union Island, St Vincent & the Grenadines with a maximum temperature of 28°C, moderate levels of heat & humidity, maximum UV of 11+ (Extreme) and 6 hours of bright sunshine. There are 5-10 mm of rainfall expected with 58% chance of some rain and a gentle breeze of 15 kph from the east.

• 28
  °C maximum temperature
• 28
  °C minimum temperature
• 
  isolated thunderstorms
• 6
  hours of sunshine
• 11
  UV index (Extreme)
• 58
  % chance of some rain
• <10
  mm of rainfall expected
• M
  moderate heat & humidity
• 15
  kph wind from E

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Sandals sale: up to £300 off Caribbean holidays

Discount Code

• Save up to £300 on all inclusive holidays to the Caribbean
• Discount varies by total spend. 7 night minimum stay
• Travel before 31st December 2027 (inclusive)

Show discount code ******ALE

Redeem Sandals discount code >>

Expires at 23:59 on Tuesday 30th Sep 2025 · View all Sandals offers

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

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