Scotland is finally on course for the hottest day of the year at last, with temperatures in the high 20 centigrade due to arrive over the next two days.

The high will make up for the disappointment of recent weeks, when the occasional warm, sunny day has been interspersed with chilly and wet conditions.

In southern Britain, temperatures are likely to soar to 35C on Wednesday, but severe thunderstorms are predicted to strike western and northern parts of the country by Wednesday afternoon cooling temperatures on Thursday.

But temperatures are likely to be on the rise again before the weekend.

Paul Knightley, the forecast manager at MeteoGroup forecasters, said the tropical continental air mass moving from North Africa, Spain and Portugal to Britain could make Wednesday the hottest day for several years.

He also warned that the sun was "about as strong as it can be" and UV levels will be quite high.

He added: "One issue will be the temperatures won't be dropping as low as perhaps we might normally expect overnight. The cumulative effect from day and night will actually be really hot."

In England, a health warning has been issued amid concerns that lives could be at risk.

Vulnerable groups including the elderly, young children and people with breathing difficulties have been urged to stay cool as the hot weather pushes across the UK from Europe.

The Met Office may issue a level 3 heatwave alert, which requires community support for at-risk groups, for south of the Border.

The Government is not doing enough to protect people from the increasing risk of heatwaves and flooding due to climate change, it has been warned.

Despite efforts to prepare the UK for the impacts of a warming world, government advisers the Committee on Climate Change warn more needs to be done to conserve scarce water supplies and fertile soils and protect against floods and high temperatures.

Building regulations needed to include measures such as the orientation of houses, shading and ventilation to prevent overheating, while efforts to halt the loss of front gardens and city green areas would keep down temperatures and reduce flash flooding.

Ministers also need to extend emissions-cutting schemes to meet targets to tackle climate change in the most cost-effective way, including the subsidy programme for low carbon power such as wind farms and nuclear.

The scheme currently runs to 2020, at a price tag capped at £7.6 billion on consumer bills in 2020/2021.

Investors urgently needed certainty into the 2020s, when the costs could need to rise to £9 billion a year in 2025 before falling, the committee said in a progress report to Parliament on tackling climate change.

Meanwhile, retreating Arctic sea ice could alter the climate of Europe and bring a chill to the UK, research has shown.

There is evidence that the transfer of heat to the atmosphere off Iceland and Greenland is lessening.

This in turn is likely to have knock-on effects on the Gulf Stream, according to Professor Kent Moore, from the University of Toronto Mississauga.