Bands and their supporters making their way to Stevenage for the London & Southern Counties Regional Championships are being advised to ensure that they check traffic updates over the weekend.
A five-mile stretch between junctions 10 and 11 of the M25 in Surrey will be closed from 9.00pm on Friday until 6.00am on Monday.
Heavy congestion
Although this may not have a direct effect on many making their way to the contest, National Highways have told drivers to "avoid the area entirely"as there could be "heavy congestion and delays"and to plan their journeys well in advance.
Jonathan Wade of National Highways told the BBC website that drivers should only use the M25 "if their journey is absolutely necessary"and should follow road signs and not rely on sat-navs to try and find a shorter or quicker route.
There are also a number of engineering works facing South West Railways on the weekend.