Saturday - take your sunscreen if you are outside all day
The sun rose over the capital this morning bringing hope of a sunny day. Cloud will not bother us through this afternoon, and with just a gentle breeze it will feel pleasantly warm with highs of 14C.
We'll have a fine end to Saturday, leading into a chilly and clear night. Temperatures could dip as low as 2C, but most places will remain frost free, apart from one or two usual prone spots.
If you are heading out first thing tomorrow, remember extra layers. It will be bright but chilly. By 9am temperatures will have recovered to a respectable 7 to 9C and winds will remain fairly gentle. The sun will be strong until about midday when the first of the high cloud will spead in from the northwest, which will herald a downturn in our weather through the afternoon. However all runners and spectators should remain safe under dry skies through the latter part of the race, albeit rather cloudy. By mid afternoon temperatures will reach 15C, but the southwest breeze will pick up a little strength by then.
The first of the rain will arrive through late afternoon, although any bursts will be light and patchy.
Expect the parks and gardens to be damp by morning as nighttime rain falls over London. Temperatures will hold up higher than the last few nights.
Monday and Tuesday
The first part of the week will stay dry by day, with a fair amount of cloud, but Monday night will again be damp or wet in places, as another weakening weather front sheds its load over the southeast.
Tuesday will be warmer than Monday with highs of 17C. More cloud generally on Wednesday but the air will pick up some heat, so temperatures will peak even higher at 18C.
Good luck to all of Sunday's runners.