think of it like this, for a lot on here they made the decision to go over to wfp, now that takes guts and is a worry in itself, now all you need to do is train the mind that working in the rain is ok as well, and if you are trad just train the mind and carry more scrims, I did two large bungalows this morning trad in the rain and was thanked and told I was doing a smashing job, then for the rest of the day I was wfp mostly in the rain and no one batted an eyelid, I was absolutely soaked when I got home, but with an extra customer on my books. sure you may get the odd one that doesn't like it but that is true about going wfp.
also year or so ago I was late to a job due to weather and a customer told me you should have just came and don't try to guess what I am thinking