From cold and gusty (in the winter during clearing winds) to downright hot and steady in the summer. This location is at it's best when the coast is fogged in and the Central Valley is nice and toasty. People wear shorties in the spring, but by summer it's board shorts and rash guards. You can ride here year-round but April to September is prime time. Temp of water is mid 60's°F. The air reaches mid 90's°F in the summer.
Wind can vary from very light to very strong. It will often be windiest in the early morning and then again in the late afternoon during the primary season. Days that average in the low 20mph range are frequent all summer long. Typically there will be periods of very high temperatures and low winds, followed by several days of cooling and high winds. The first day of the cool-down is frequently the optimal set-up for high winds which average in the high 20 to low 30mph for several hours each day. The wind is typically sideonshore with a predominant SW direction. From gusty (in the winter during clearing winds) to steady in the summer. SW is best direction, but also works on West and South. North wind is not good.
On the San Francisco Bay delta, also known as Rio Vista. From San Francisco/Oakland: Take Hwy 680 to Walnut Creek take Hwy 242 going towards Concord. Continue past Concord on Hwy 242 Merge east towards Antioch on Hwy 4. Go past Antioch. Merges with Hwy. 160 and cross the toll-bridge. Take the first left turn after the bridge, Hwy. 160, and get onto W. Sherman Island Rd and access the water when it makes a little s-bend.