UK weather: Finally there's sun-thing to smile about: Forecasters say Sunday's temperature may rise to 20C making it the hottest day of 2013 End of the cold spell finally here, although weather remains unsettled Outbreaks of rain in south west expected to drift across the UK Rare birds dying as they struggle to find food when they arrive in the UK The end of the cold spell finally arrived today as the sun started to shine, and forecasters have said temperatures could be about to rise even further. Sunday is expected to be the warmest day of 2013 so far, with temperatures reaching as high as 20C in parts, although they will fall again by the start of next week to what would be expected for this time of year. But while many took advantage of the warmer temperatures and enjoyed some sunshine today, forecasters have warned rain will spread across the UK as the weather remains 'mild but a bit unsettled' over the next few days. People were able to enjoy the spring sunshine on the River Cam, in Cambridge, today, but forecasters have said the weather will remain 'unsettled' until the weekend A couple (left) and a group of friends (right) enjoy a spot of punting on the River Cam today underneath trees that are finally beginning to blossom People enjoy the spring sunshine as they punt past the cherry blossom trees at Magdalen College, in Cambridge, today Charlie Powell, forecaster for the Met Office, said: 'It hasn't been too bad today for a lot of places, particularly western Scotland and north west England - temperatures have got up to double figures. Rare birds have been found dead in the latest sign of wildlife struggling to cope with the cold spring, conservationists have said. The bodies of eight stone curlews, a threatened species which migrates from wintering grounds in Africa and Spain in the spring, have been found in fields in Wiltshire, Norfolk and Suffolk in the past few days. Conservation charity the RSPB said the birds are believed to have struggled to find food on their arrival to the UK and were just two-thirds the weight they should have been if they were healthy. Only around 400 stone curlew pairs are in the UK, and the last two years have been poor for breeding. The discovery of eight dead birds, with the actual number that have died likely to be higher, is a stark reminder of how fragile the species is, RSPB conservation director Martin Harper said. Hundreds of puffins and other seabirds were found dead two weeks ago off the coast of Scotland and north-east England, as a result of freezing conditions and stormy weather making it hard to find food. Nature enthusiasts are reporting little evidence of the annual influx of summer migrants which normally arrive at this time of year to build nests and breed. Reports of chiffchaffs, willow warblers and black caps have been scarce. That kind of marks the change to a fairly significant change of weather type as we head into the next few weeks. 'Admittedly, for the next couple of days, particularly in the north, it's going to be on the chilly side in terms of the temperatures. We are still looking at single figure maximums, there is still cold air sitting over there, the same cold air that we have seen over the last couple of weeks, but it has been modified as we start to see rain and wind pushing in from the south and south west over the next couple of days. Mr Powell said the weather will be 'a bit unsettled' but mild through the rest of the week. Temperatures across much of the north tomorrow will still be below average, at about 7C to 8C, although it will be warmer further south, where temperatures could reach 11C or 12C. He said: 'So we are beginning to get where we should be.' But he did warn outbreaks of rain in parts of the south west of England will drift across the rest of the UK. High pressure meanwhile is expected to build on Friday with some sunshine in most places and temperatures getting into double figures. By the weekend temperatures are generally expected to be between 11C and 13C, although it will still be wet, fairly windy and unsettled in parts. On Sunday however, the weather is expected to be slightly more settled and much of the country is expected to see temperatures rise to the mid-teens. The south and east will see the best of the weather, with the possibility of temperatures in some spots, such as East Anglia, hitting 20C, along with drier and brighter conditions. Mr Powell said: 'Then things will settle back down to average for the start of the working week.' The weather is expected to remain unsettled over the next three days, with rain spreading across the UK from the south west, but temperatures will hit highs of 20C by Sunday Today marked the end of the recent cold snap, and temperatures are expected to rise to as high as 20C in parts of the country by Sunday A man mows the lawns at Shobnall Park in Burton-on-Trent, Staffordshire There was even a chance for a spot of cricket at Trent Bridge, Nottinghamshire, today Blue skies can be seen in the North East. Warmer weather is on its way from this weekend A car drives through the thawing snow as temperatures remain around freezing in Teesdale, County Durham, yesterday Icy conditions: The temperatures remained low yesterday but are expected to have vastly improved by Sunday