In Northern California, Summers are relatively mild in that it can get hot during the day but morning are normally cool and humidity is low. Here is typical running, race attire for long slow summer weekend runs:
Shoes : Montrail Rogue Racer About 9 oz shoes, sort of a neutral shoe with a little mid foot support and lugs on the bottom for traction.
Socks : Asics low-cut three for $12 at National Running Center (NRC)!
Shorts : I like the Frank Shorter's Marathon split running shorts when they are on sale for $16. Or, the regular non-split when they are on sale for $10. Can't get a better, lighter pair of shorts for $10!
Singlet Tops : Frank Shorter's Accent Tank Top when on sale for $16 or less. Comes in four different colors either on white or solid. Excellent tops. I like the high-visibility especially at night with the reflectors that are iron-on the back of the shirt.
Hat : Basic 'head sweats' hat with front liner to help control sweat. Normally $10 and if I'm doing an order at NRC I'll add a head-band for winter.
iPhone arm band : I've tried a bunch of them and my favorite is the iFitness arm band because it had a half zip side to allow easy access to the phone while you are running to take pictures, made out of neoprene so it doesn't pinch, will accommodate iPhone with case and comes in different colors.
Accessory Belt : Can't beat the classic SPIbelt for comfort and flexibility. I normally keep a packet of GU, car keys and $20 just in case. Put money or anything you don't want to get sweater in a baggy first just in case.
22-oz hand held : I have many, many hydration systems, but the one I always have with me and count on is the CamelBak Quick Grip because the grip is comfortable, secure and has a strap to sinch down for a tight ... well ... grip. There is also a small zipper pocket on the side for a car key, some money and a GU - but not much else.
As soon as the early morning weather drops below 60, I'll transition to CW-X pro racing tights not only for the bit of insulation but integrated band puts that little extra spring into your step. Very comfortable. However, there is a seam around the crotch so I'd recommend also wearing technical underwear with it.