Hundreds of homes in Cambridgeshire are without power after torrential rain and strong winds battered the region and caused road closures, public transport disruption and flood warnings.
UK Power Networks said high winds had blown trees and debris on to overhead power lines overnight, causing extensive damage.
Greater Anglia is running a limited service, with delays and cancellations.
First Capital Connect has started running services, but with continued disruption between Kings Cross and Cambridge.
In Cambridgeshire 1,590 homes lost power, 1,807 in Essex, 400 in Hertfordshire and 1,900 in Suffolk.
And the Environment Agency has issued flood warnings for Bury Brook from Kings Ripton to Ramsey.