We use the layering method of keeping warm. For the outside we use Gear or Holloway wind shirts and warm up pants like the runners wear. To make them rain resistance we simply buy pure silicon lubricating spray and then lightly spray the clothing we wear as an outer layer. This makes them water resistant without stopping them from breathiing. We find that it makes the clothing able to keep us from getting wet. When you wash the clothing you just re-apply the silicon again. It also works to protect high quality leather from cold and dampness. I put it on all out smooth finished leather jackets. I learned this trick from the Carhart rep who came to our local suburban farm and home store to treat Carhart coats and bibs to renew their waterproofing.
Hope this helps.