<p><br /> High temperatures and humidity are likely to make Sunday's Virgin London Marathon one of the hottest ever.<br /> </p><p><br /> Forecasters are predicting the warmest temperatures of the year this weekend with the mercury set to hit 21C in the South East and London over the weekend.<br /> </p><p><br /> That would make Sunday's race the third hottest after the 1996 and 2007 marathons.<br /> </p><p><br /> But light showers could provide some relief from the warm temperatures.<br /> </p><p><br /> The sunshine will return to the South East on Monday with forecasters predicting a warm start to next week.<br /> </p>
