There’s always the possibility of rain, anywhere on any day.
Absolutely this! MN is often really weird about weather as though "abroad" guarantees sunshine - but obviously not too much sunshine or they will have to cower indoors all day.
It's not that long ago that there were numerous threads along the lines of "we booked a holiday abroad but it's forecast to rain all week, shall we cancel?"
More recently, people have been considering cancelling because (e.g.) the South of France is going to be too hot in August (no shit Sherlock)
"Weather" - whichever type floats your boat - is not guaranteed, and long range forecasts change on a daily basis.
Some posters are now wishing that they had stayed in the UK this year to take advantage of the high temperatures. I'm pretty sure that if those posters decide to book a UK holiday for August 2026 then they will be moaning about the fact that it's going to be raining (not unlikely!).
We went on a long-haul holiday earlier this year and the forecast right up until the day we left said solid rain for 2 weeks. Bit of a shame, but them's the breaks. We actually had two weeks of glorious sunshine. Very glad we didn't cancel (not that we were considering doing that).
OP, you could change the date, but what if the forecast then changes? How many times would it be feasible to do this?
Try not to stress, the weather on the day will be what the weather on the day is. I hope you have a lovely day.