WASHINGTON--(BUSINESS WIRE)--Washington Gas today announced that customers in the Washington, D.C.-area may experience a decrease of up to 6 percent in heating bills during the 2019-2020 winter season compared to last year as gas costs are forecasted to be slightly lower than last winter. If colder-than-projected temperatures drive added demand to keep homes warm, natural gas prices may vary and bills may be higher. Washington Gas also urges customers to follow several simple but important ener