FERC has directed utilities to fine-tune line ratings in order to boost transmission system efficiency. They are ordering all transmission owners to account for ambient conditions when determining how much power can flow through their lines. FERC’s new ratings will require transmission owners to update their transmission line ratings at least hourly, rather than using the more typical seasonal or static ratings that are usually updated when equipment is changed or weather assumptions are revised. Utilities have three years to use these new line ratings after they file compliance plans at FERC.