Most Jersey Heritage sites will now stay open year round.
Extra government funding means the trust that looks after them can open them daily - even off-season.
Some of the visitor attractions had closed between October and March.
The exception will be Elizabeth Castle, which will still close in the winter months because it is hard to reach in bad weather.
Chief Executive Jon Carter says year-round opening marks 'an exciting new chapter for Jersey Heritage' and the 2019 States decision to commit 1% of its annual budget to supporting arts, heritage and culture has 'emboldened' the trust to take the decision.
"The incredible local support we have received over the past few years has also played its part; visits by Islanders to our sites have tripled and now account for about 30% of overall visits.
We have also seen a significant increase in the number of people becoming Jersey Heritage Members and expressing their support for our work."
From 1 March, all Jersey Heritage visitor sites will open daily. That includes Hamptonne Country Life Museum, La Hougue Bie and Elizabeth Castle, which have been closed since 1 November.
Mont Orgueil Castle and the Maritime Museum have been open on reduced hours through the winter.
JH is recruiting Site Guardians and Visitor Service Assistants and says staff new and old will be offered longer hours to cover the increased opening times.
Economic Development Minister Deputy Kirsten Morel has welcomed the announcement:
“This is great news and ties in perfectly with the new Heritage Strategy launched last year and will be welcomed by Islanders and by visitors to the Island, who now have even more opportunities to learn about and benefit from Jersey’s rich history.”