Some forces have warned they may have to crack down on those deemed to be flouting the rules, with the power to remove someone using “reasonable force, if necessary” and issue fines of up to £960 in Scotland and England.
Temperatures could reach up to 24C on Good Friday, particularly in London and the south east, where it is expected to remain mild well into Saturday evening, despite the likely arrival of showers midway through the afternoon.
As a result of high spring tides, four flood warnings are currently in place along the Severn Estuary, and another at Hornsea in the northeast, where large waves could overtop sea defences and some coastal properties are at risk.
Flooding is possible at another 47 locations, mainly in the south of England, where the prospect of heavy rain has led to the Environment Agency to warn that groundwater could rise to disruptive levels.
While Scotland’s showers are forecast to abate by Saturday morning, the rest of the country will likely experience intermittent showers throughout the weekend, which have the potential to turn stormy.
“As the weekend continues there is an increasing risk of showers, some of which could be heavy or thundery,” said Met Office meteorologist Frank Saunders.
While conditions appear set to dry up by early next week, the Met Office warns Easter will mark the start of a changing pattern to cooler weather for many parts of the UK.
“By the start of next week, although it will be drier and sunnier again it will definitely feel cooler with temperatures reaching the mid-teens at best.”
As nights become chiller, there will be a return to a risk of frosts overnight, especially in central and northern areas.
Although confidence is low for the following weekend, the most probable scenario is that dry weather will dominate, the Met Office said.
However, sunnier climes and steadily rising temperatures in London, starting on Wednesday, will resurrect hopes for another warm weekend in the south.
Additional reporting by PA