I live in the eastern part of the UK and our weather generally comes from the west so by the time it reaches us there really isnt much weather left. The forecasts say rain this and gales that but I get wet a handfull of times each year.
If your weather is unpredictable you just have to carry kit for the worst conditions of the day. In winter my bag usually includes waterproof pants and sock, a neck-warmer tube, a wooly hat and a insulated gillet sleeveless jacket.

I can understand that people in deserts don't want to spend loads on expensive waterproofs. Buy the cheaper breathable ones instead; they are not as tough and durable but then you dont wear them as much.
A water-resistant windproof is a good investment for cold conditions.