The Department of Infrastructure says a section of the TT course will close for two weeks from Monday.
Drainage and resurfacing works means Creg Willey's Hill will shut between Ballig Bridge and Cronk Y Voddy from 9.30am on Monday, March 17.
The DOI says TT organiser ACU Events described the work as essential for this year's racing - because water could seep onto the road and create a race hazard.
Traffic will be diverted via Poortown Road.
More than 270 get Duke of Ed awards
Plans for Lord Street development to be reconsidered
Coastguard teams mount search after beacon activated
Government working with fuel suppliers as demand spikes over war
Film company wants your help during TT
Lieutenant Governor to host special event for charity founder
Two sailings delayed by bad weather
Just weeks to raise £5k to join Dolly Parton's initiative