The MCA says rescue workers will not be affected by the strike
Coastguard staff around the UK have begun a 48-hour walkout in a long-running dispute over pay.
The rescue co-ordinators, part of the Public and Commercial Services Union (PCS), are angry they are paid less than other emergency services.
As many as 700 Maritime and Coastguard Agency (MCA) staff could take part in the stoppage.
The MCA said rescue workers would be unaffected but urged people to take extra care on the sea, beach or cliffs.
The Bank Holiday weekend strike follows five days of industrial action earlier this year at the UK's rescue co-ordination centres.
The PCS claims staff have experienced real-terms pay cuts, with pay rises averaging 2.5% for most staff, and less than 1% for senior personnel.
Staff want a rise of £3,000 on their current base salary of about £12,500 a year.
Paul Smith of the Public and Commercial Services Union (PCS) told BBC News that staff in the operations rooms were earning just above the national minimum wage.
"The salaries our members earn in the Coastguard Agency are significantly behind those within the other emergency services," he said.
"The jobs our members do is highly responsible, highly trained and frankly they've had enough because they see the writing on the wall unless this issue is properly addressed."
The Public and Commercial Services Union's Paul Smith
The PCS said strike action could have been avoided if the government and MCA had negotiated "a satisfactory outcome".
On what is expected to be one of the busiest weekends at sea, the MCA said contingency arrangements had been put in place to ensure that it continued to provide an emergency service.
MCA chief executive Peter Cardy said "normal service" would be unaffected.
Rescue helicopters, Royal National Lifeboat Institute (RNLI) boats would continue to operate and volunteer coastguard rescue officers would be ready, the agency added.