If you’re looking forward to exploring Sonoma, CA, by bike, springtime is the perfect time for a visit. When to Visit: Sonoma, CA is blessed with good weather year-round. If you’re looking forward to exploring Sonoma, CA, by bike, springtime is the perfect time for a visit. The mornings and evenings are cool and daytime temperatures typically stay in the 70s and 80s. If you time your visit right, you’ll enjoy fields full of vibrant yellow mustard flowers and spring blooms aro