Tony Frost and Jon Trott resumed from their overnight scores. The pair put on 47 runs before Frost was caught just six short of a century.
Tim Ambrose and Rikki Clarke were out for ducks with Ant Botha only making two.
Trott had taken his score on to 79, hitting 13 fours but he fell to a catch by Trescothwick.
The tail end was soon mopped up and Warwicks were all out for 261.
Marcus Trescothwick hit 108 in the first innings and made 107 not out in Somerset's second innings as the visitors ended on 156-4 and the match was declared a draw.
Tomorrow, Warwickshire take on Leicestershire in a Pro40 game at Edgbaston. Play is due to start at 1.45pm.
In the Ashes match, Australia made 445 in their first innings. England in their second innings closed on 82/5.
Ian Bell made only three runs.