Met Office say the arrival of a plume currently causing heatwave conditions on the continent will see the mercury jump up to 34C by the end of the week.But they also warned that the scorching summertime weather will likely lead to some uncomfortable evenings — and may even be dangerous during the day.A level 2 heat-health alert has been issued from Friday (June 17) to Sunday (June 19) for the East Midlands, the southeast and the southwest, with a level 1 alert in place for northern England.Met Office Deputy Chief Meteorologist, Dan Rudman, said; “Temperatures will continue to rise as we go through the week, becoming well above-average by Friday when many parts of the southern half of the UK are likely to exceed 30C and may even reach 34C in some places.” “This is the first spell of hot weather this year and it is unusual for temperature to exceed these values in June. "Many areas will also see some warm nights with minimum temperatures expected to be in the high teens or even low 20Cs for some overnight.” He added that the warm spell was down to a "mix of home-grown warming in the day due to high pressure" as well as a "southerly airflow introducing some of the warm air from the continent to UK shores.” Health officials meanwhile want people to ensure that they are looking after the old and seriously ill amid the heat.Agostinho Sousa, Head of Extreme Events and Health Protection at the UK Health Security Agency, said: “Temperatures are forecast to reach 30C in some parts of the south on Friday and we want everyone to enjoy the hot weather safely when it arrives and be aware of good health advice for coping with warmer conditions.“During periods of hot weather it is especially important to keep checking on those who are.