He may not have noticed the rain, but it’s not really clear that he could have done anything different even if he had.

They have a time window in which to send the photo back and he was right by the station (revealing to the audience where he was, by showing a name sign). The rain clouds on the radar didn’t look that big, and the UK is very often a changeable “don’t like the weather? Wait five minutes” country, so waiting a few minutes may have made it less obvious.

Maybe there was no hiding spot good enough, but now we’ll probably never know.