@Irene531 You should always inform guests of unexpected weather events that may affect their stay, especially when safety warnings have been issued. In this case, the weather may make your listing unsuitable to stay, so I would be quick as you can to highlight this to them. Say you understand if they wish to cancel...weather is something you can’t control... be up front and understanding etc.
If they decide to come anyway, you will need to have a clear backup plan to accommodate them, in case your RV becomes unsuitable. If that’s not practical for you, then I suggest getting in touch with Airbnb. If it’s a published weather event, they will probably offer to cancel the reservation for you, consequence free.