The storm, which is the result of a low pressure system moving west to east, is forecast to generate force 6 to 7 winds throughout the weekend and into early next week, with the gales set to reach their strongest at a force 8 tomorrow morning.
For comparison, at its apex, Storm Ciara registered force 10.
Smaller tides and fewer gusty spells should see fewer waves crashing onto the coast roads, although a near-constant deluge of heavy rain is forecast from Saturday lunchtime through Sunday.
There is also a risk of hail, thunder and lightning on Monday morning.
Despite being milder than Ciara, Dennis is still causing travel disruption.
Condor has cancelled all sailings for the Liberation and the Rapide this weekend and has advised travellers to rebook to a later date.
Yesterday’s Clipper sailing was cancelled, but the ship did go to Jersey.
Flybe has offered customers extra rebooking options should they not want to travel this weekend.
‘Please be assured that we will be doing our best to operate our services as normal, taking into consideration any adverse weather conditions,’ said a spokesman.
‘You can rebook your flight on the same route for any future date, providing that seats are still available at the same price as that originally paid.
‘If you would like to choose an alternate flight, please note that we will waive any change fee for your booking, however you will have to pay any change in fare.
‘You can rebook on a different flight for travel within the next seven days at no charge to the same or a similar destination, providing there are available seats.’
Aurigny is also offering a flight change option.
Passengers can change to another flight (same route/name) within the next three days for no extra charge. If you change to a flight more than three days in advance, the airline will still waive the change fees but passengers may need to pay any fare difference.
The airline also warned it could experience some disruption later today and tomorrow morning.
In particular, the Dornier aircraft that ply the Alderney route are expected to struggle with crosswinds.