Flu clinic pay for RN`s

Just wondering if a 21$ hourly rate in southern California is a ok compensation for this type of job. It would be a 3.5h clinic about 45 min drive each way. Is it worth it? is that what they usually pay for this type of job? I make much more working on a acute care floor and I figured a short contract would pay more than my current job. Please advice if this is a ok rate .