Somerset will start the Bob Willis Trophy with a home match against Glamorgan on August 1.
All 18 first-class counties will take part in the new red-ball competition, which replaces the County Championship in 2020, after being split into three regional groups.
Somerset – runners-up to Essex in 2019 – are in the Central Group and after hosting Glamorgan will visit Northamptonshire on August 8.
They travel to Edgbaston to take on Warwickshire on August 15, then return to home soil to entertain Gloucestershire at the Cooper Associates County Ground in Taunton on August 22.
Their final group game is against Worcestershire at their Blackfinch New Road base on September 6.
The two group winners with the most points are set to progress to a five-day final.
Somerset are waiting to hear from the ECB Cricket Disciplinary Committee whether a 12-point penalty imposed last September, due to come into force at the start of this summer’s County Championshpi, will apply for the new competition.
Western Storm are also returning to action in a special edition of the women’s domestic 50-over competition that includes two groups of four teams, with the winners contesting the final.
Fixtures for the women’s competition are set to be announced, along with confirmation of the full schedule for the men’s Vitality Blast, which is due to begin on August 27, next month.
Somerset Director of Cricket Andy Hurry said: “There is enormous excitement about playing competitive cricket again.
“Some of the teams in our group we last met in four-day cricket back in 2007 when we were in the Second Division of the Championship.
“We would have been playing Gloucestershire anyway this season following their promotion and we are delighted to be welcoming them to Taunton for a match that will create enormous interest.
“That applies to the competition as a whole and we will go all out to win it. People will be talking cricket again once it gets underway and that is fantastic for the game as a whole.”
The domestic competitions will be staged under strict health and safety protocols with the Bob Willis Trophy also set to feature ECB Board-approved changes to playing conditions to help ensure the wellbeing of players, most significantly fast bowlers, following the long lay-off due to the coronavirus pandemic.
Playing conditions have been put in place after extensive medical research and in collaboration with the first-class counties and Professional Cricketers’ Association.
These include each day’s play being reduced from a minimum of 96 overs to 90 overs; each first innings lasting no longer than 120 overs; the follow-on increasing from 150 to 200 runs and the new ball being available after 90 overs rather than 80 overs.