Windy weather towing

We got our first caravan this year and it's been a very wet but not very windy year so far.  Coming towards the autumn and with stormy weather forcast, I'm wondering at what point you say No, it's too windy, we are not going.  I've seen a few caravans on their side on the M62 close to where I live so wondering if you experts have a rule of thumb about this.