Festival of Motorcycling organisers say there'll be a one-hour delay to today's programme.
It's the final day of racing at the festival, with the Senior Manx Grand Prix due to get underway.
Clerk of the Course Gary Thompson says after advice from Ronaldsway Met Office the race will be held back because of mist and low cloud over Snaefell.
Roads will now close at 10.30am, with racing set to start at 11.15am.
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