The fan park at the TT Grandstand will be closed this morning.
Heavy rainfall overnight means ground conditions are in a very poor state.
Organisers say contractors are assessing the situation and trying to improve access.
They add they're hoping to reopen the attraction later.
50-acre remote sanctuary up for sale
Northern tip's re-use area to open again next month
Mountain Road closed for TT sign removal
Decision on Summerland campaigners' appeal this week
More works on Old Castletown Road this week
Airport says flights may be affected by morning's fog
Could the Grandstand be getting a new entrance plaza?
Caine to defend seat in general election