I just googled water rating charts...hmmm
Rating Resistance Weather Conditions 0 – 1,500mm Water resistant / snowproof Dry conditions or very light rain 1,500mm – 5,000mm Waterproof Light to average rain 5,000mm – 10,000mm Very Waterproof Moderate to heavy rain 10,000mm- 20,000mm Highly Waterproof Heavy rain