Weather officials have warned Londoners to prepare for high levels of air pollution as a cloud of Saharan dust makes its way towards Britain.
Temperatures are set to reach highs of a cooler 13 degrees on Thursday (April 7) after a weekend which saw the city get hotter than Madrid .
But it comes with a sweeping southerly wind which will see Saharan dust blown across the country, which could cause health risks to vulnerable groups.
The Department of Environment, Food and Rural Affairs (DEFRA) said those at risk, including people with lung and heart problems, should "reduce strenuous physical exertion".
Director of Asthma UK Advice Andrew Proctor told getwestlondon ahead of a toxic smog forecast in December said two thirds of people with asthma find air pollution makes their asthma worse - and even more tell them that changes in the winter weather can trigger asthma attacks.
Tips for managing respiratory problems during the spell include making sure there is enough medication available, carrying it at all times and checking air pollution levels before leaving the house.
Sophie Yeomans, from the Met Office, said average temperatures for early April were normally around 11C or 12C, matching the forecast for London this week.
Unsettled bouts of rain, cloud and cooler weather is expected for Monday (April 4) and Tuesday, dropping down to 11 degrees on Wednesday, according to the Met Office .