Don't be fooled by the sunny pictures from last year's Games. Aromas in the mornings and evenings can be cold. Even on the hottest days, the temperature drops dramatically with the sun.
Layers are key in Central CA. Pack them. Also, sunscreen. Change of clothes. A source of shade if you can. There will be food and drink on hand, but it's a good idea to bring a cooler with some necessities. There are no stores or markets close by, so be prepared.