Rain has a terminal velocity of maybe 20 MPH falling straight down. But, it turns out, raindrops in 40 MPH wind are moving 40 MPH horizonally, in addition. I know, because I did the measurement this last weekend. And so did my tent. The 40 MPH winds blew my tent around until it started to collapse and tear. I discovered a lot of things, not just raindrops, have impressive force when moving at 40 MPH. Like hawthorn blossoms.
But my tent protected me through the night, and part of the next day. Only when the rain started pooling in the place beside the lake where I had set up camp did I have to break camp and head out of the mountains. Which afforded me the opportunity to have a short beach holiday in Wales, in Barmouth.