People have been warned to avoid beauty spots this bank holiday weekend, as temperatures are predicted to soar across England.
Emergency services and other authorities said travel to beaches and national parks would "cost lives".
The country will be bathed in sunshine over the VE Day bank holiday on Friday, with warm weather also forecast for central and southern areas on Saturday.
Boris Johnson is expected to announce plans to ease restrictions on Sunday.
The prime minister was reviewing the coronavirus lockdown in England with his cabinet on Thursday.
Dorset Police also said the county was "closed".
Devon and Cornwall Police's Assistant Chief Constable Glen Mayhew said: "To those thinking about travelling to the South West for holiday or social purposes, please come back later.
"Now is not the time for complacency and we must all continue to adhere to the advice which includes social distancing and only making essential journeys outside of our homes."
Cumbria Police also tweeted to urge people to avoid the scenic Lake District and said the county had "high infection rates and people are still suffering and dying in our hospitals".
The county's tourism industry leaders added to the plea, with a Lake District National Park Authority spokesperson claiming flouting the rules "will cost lives".
Gill Haigh, managing director of Cumbria Tourism, said: "When it is once again safe to travel our businesses look forward to welcoming you back - but that time is not now."
More than 100,000 key workers were put at the centre of a social media campaign, along with council leaders in the South West, thanking tourists who keep away until government guidelines change.
Key workers across the South West are saying thank you to everyone who keeps away from tourist hot spots in Devon & Cornwall this #VEDay bank holiday.— @cornwallcouncil (@CornwallCouncil) May 7, 2020
Do you really need to make that journey? @GOVUK says only travel if it's essential.#TeamCornwall 💚 #ComeBackLater #VEDay75 pic.twitter.com/HUcYqyI5X4
Lockdown rule breaches:
A spokesperson for Forestry England urged people not to visit the New Forest National Park in Hampshire after "a range of emergencies" in recent weeks, including "forest fires, anti-social behaviour, off-roading drink-driving, medical emergencies, vandalised gates and wild camping".
Elsewhere, North Yorkshire's Police, Fire and Crime Commissioner Julia Mulligan wrote an open letter saying those who were tempted to travel would put emergency service staff at risk of contracting coronavirus.
"Over the past few weeks, a minority have concluded the rules do not apply to them and have travelled substantial distances to North Yorkshire," she said.
"This weekend, the prime minister will set out the roadmap to easing the restrictions we face. We do not know what he will say, but we do know that until then the current instructions remain. And they do not include taking a daytrip to North Yorkshire."