The 33-year-old Woakes is unavailable for June's first Test against New Zealand at Lord's with a longstanding knee injury, and an ankle issue, which have kept him out of action for club and country since March.
Woakes is part of a long tally of England bowlers on the injury list. Jofra Archer, Saqib Mahmood and Matt Fisher have suffered stress fractures in their backs, while Mark Wood and Sam Curran were also ruled out of contention to face the Black Caps.
"Woakes has been struggling with a knee injury and has also had a little ailment with his ankle," Warwickshire head coach Mark Robinson told the club's website.
"But it's the knee injury that is holding him back. At the moment there is no timescale on when he will be back."
Olly Stone has already discounted the prospect of appearing for England's Test side this summer after suffering a stress fracture in his back last June.
A knock to his hip has set him back in his recovery but Robinson is optimistic about Stone returning in the next week or two in the Vitality Blast, which gets under way on Wednesday.
"Stoney has had a niggle around his hip cartilage which he picked up in a Second XI match," Robinson added.
"We thought we had got him back but then he aggravated it in a club game, but he is progressing and is probably about 10 to 14 days away from ready, depending how quickly it heals.
"We are definitely hoping he will play some part in the Blast, though whether he will have the overs under his belt to play a four-day game in that interim period, we don't know."