Have a quick nose on the local BBC weather page but then make my own decision. If I'm playing a social round I might take a chance and just pack a waterproof top but if I'm in a competition and the forecast is for heavy showers or longer periods of rain I'll pack my waterproofs, a couple of spare gloves and several small towels.

I tend to trust the BBC weather but will make a decision normally once I get to the club and can see the prevailing weather coming in