We've scanned every flight from Southampton to St Lucia to find the best deals. If you want a cheap flight, it's best to be as flexible as you can on dates. If that day's no good for you, try searching by month to see some alternative dates.
St Lucia Hewanorra International Airport is just one of the airports in St Lucia. If you're not set on a specific airport, try changing your search from St Lucia Hewanorra International Airport to St Lucia to see a broader range of flights – they might be cheaper.
If you're planning on going to St Lucia during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.