The MGP Newcomers race has been postponed until tomorrow, following delays of more than three hours today.
Roads were due to close at 9.30am this morning, but the latest announcement has pushed the closure back until 1.30pm.
A helicopter is currently inspecting the course to see where mist remains – with conditions preventing the racing go ahead so far.
Currently, the Junior Classic TT race is due to get underway at 1.30pm, followed by the Superbike Classic TT at 4.15pm.
The Clerk of the Course is also appealing for more volunteers to come forward to marshal tomorrow.
Roads are expected to open by 7.30pm