The weather is set to be warmer this week as the government battles to keep people indoors to curb coronavirus.
Prime Minister Boris Johnson announced strict social distancing measures last Monday, banning anyone who is vulnerable or elderly to stay at home and self-isolate for 12 weeks.
After Britons repeatedly flouted the advice to stop socialising and stay away from crowded areas, the PM ordered restaurants, bars, pubs and clubs to close on Friday to combat the spread of COVID-19, a strand of coronavirus.
Over the weekend, political leaders criticised those who flocked to public parks, such as Snowdonia in Wales and Richmond Park in west London, and did not abide by the two metres apart rule.
Representatives for the parks are now threatening to close the public spaces, and Mr Johnson has warned further measures could be taken to prevent people from socialising.
The weather is due to improve in southern parts of the UK this week, with temperatures reaching 18C (64.4F).
According to the Met Office, Monday and Tuesday will be largely dry and bright, with the sunniest days in particular for the southeast.
The northeast will see some rain on Wednesday, which will move southeastwards across the north through Thursday, with colder, showery weather following.
The rest of UK will be dry and mostly sunny with some mild days and frosty nights.
Northern and northwestern Scotland meanwhile will see some clouds, wind and rain on Monday and Tuesday, however this will improve later on in the week.
Sky News weather presenter Jo Edwards said: "Whilst much of the UK mainland will see some lovely sunshine today, the rain over the far north-west will stall and become slow moving.
"The rain may be heavy at times, and there'll be some coastal gales. But it's the fact that the rain belt is not going to move very far until Wednesday that means that the Hebrides and Highlands may see up to 150mm of accumulated rainfall."
She added a chilly east wind will swing round to the south, making temperatures a lot milder.
"They will reach 17C or 18C in some parts - that's a very springlike 64F. In sheltered spots that will feel very pleasant indeed," she said.
"But don't rush to switch the heating off - there'll be patchy overnight frosts throughout the week, and as the rain belt clears south and dies away on Friday it'll become cold again, with wintry showers even to low levels."
At a press conference in St Andrew's House in Edinburgh on Sunday, Scotland's First Minister Nicola Sturgeon criticised people who ventured out to pubs and bars over the weekend.
She said: "Let me be clear, the advice should not be considered optional, it should be seen instead as a set of rules to be followed."
After a spike in visitors to Snowdonia - which chief executive Emyr Williams said was the "busiest day in history - First Minister of Wales Mark Drakeford hit back on tourists flocking to the national park.
He said in a statement: "Self-isolation for those who have symptoms and social distancing by everyone is absolutely essential at this stage if we are to delay the spread of this virus and save lives.
"We all need to follow this advice now to protect each other and our families and to help ensure our NHS is not overwhelmed.
"Social distancing includes avoiding all but essential travel and if people don't follow this advice we will have no choice but to use powers to enforce it."
In the capital, west London borough Hammersmith and Fulham announced it had closed all of its parks.
Meanwhile Royal Parks, the charity which looks after London's major parks including Hyde Park and Richmond Park, temporarily banned cars from entering Richmond, Bushy and Greenwich Parks after dozens of people flocked to the open spaces over the weekend.
The playgrounds, cafes and kiosks have also been closed until further notice.
Cyclists are still welcome but must not travel in groups and should stay two metres apart.
A statement from the charity said the measures were taken after people "ignored" the government's advice on social distancing - and threatened to close all parks in the future if people did not comply with the rules.
"We hope that by closing these parks to cars we will help mitigate this situation," it said.
"We understand the important of being able to continue cycling in our parks for both physical and mental wellbeing, but if cyclists do not adhere to these guidelines, we will have no choice but to close the parks."