Hampshire, Nottinghamshire, Northamptonshire and Warwickshire will prepare for the coming campaign with a pre-season tour to Barbados.
The four counties will play one another in a limited-overs competition during mid-March, around the same time that England face West Indies in three Twenty20 internationals on the island.
For Hampshire, it will be a fourth consecutive pre-season trip to Barbados. Their director of cricket Giles White said: "Barbados has been a huge part of our preparations for the last few seasons and it's hugely popular amongst the players so it's great for us to go back.
“Being able to enjoy conditions similar to that of the English summer as early as March gives us the best possible preparation for the season and will hopefully help us to hit the ground running.”