Surprised in this day and age the FA allow matches to be called off for waterlogged pitch still. You can't help bad snow for the old "surounding areas" arguement or what happened in Carlisle. But general bad rain it would be more conveinient to travelling fans, programme printers, catering, both teams etc to use a Wimbleon centre court or cricket ground style cover to cover the whole playing area. Work out much cheaper than calling it off on the day and wouldn't be expensive compared to using undersoil heating to put the bill up.
I can give it now: heavy rain. As the crow flies I'm about 5 miles from Gigg Lane, my garden is waterlogged. Luckily I haven't got a game scheduled on there tomorrow.