How much hotter does it get during the summer in Rolling Hills Estates vs. Palos Verdes Estates?

There are several weather systems on the Palos Verdes Peninsula. A great book written by weatherman Don Gales years ago, went into great detail about all of the different weather systems peculiar to the Palos Verdes Peninsula. He examined at least 50 years of records. Here is the information about it: Gales, Donald Moore. Handbook of Wildflowers, Weeds, Wildlife, and Weather of the South Bay and Palos Verdes Peninsula. 3rd Ed., Palos Verdes Peninsula: It explains the Catalina Eddy and other phenomenon. Primarily what you should know is this:
Any areas facing the ocean are colder than those facing the areas to the north. Of course, that is because there are ocean breezes that keep things cool most of the time. Also, in June, the June gloom makes the ocean side foggy while the non-ocean side can be clear as a bell. I suppose if you could draw a line differentiating the two sides, it would start at Malaga Cove and continue south as the crow flies onto Granvia Altamira and continuing to Crest Road. However, the east side of the Peninsula is noted to be the warmest side of the "Hill". It can be as much as 15 degrees warmer than the "cold side". The Valmonte area in Palos Verdes Estates is on the warmer side of the hill as is most of Rolling Hills Estates.
Dr. Melanie Patton Renfrew has a blog that addresses the weather very helpfully. Here is her link: http://drmrenfrew.wordpress.com/2010/04/23/palos-verdes-meteorologist-donald-gales-says-p-v-and-the-south-bay-get-afternoon-sea-breezes-virtually-every-day/
I hope that helps!

Kathy did a great job of explaining the weather on the Hill. When my sons were in little league, one day in the summer, the temparature on Palos Verdes Drive North at the Rolling Hills Little League field was 95 and the temperature at my home in Lunada Bay was 65, a 30 degree difference!!! There are numerous micro climates on the hill. One of the most interesting to me is that when the entire Santa Monica Bay as well as most of the ocean side of Palos Verdes is socked in with fog, the fog typically does not move up into Valmonte. Another weather pattern is that when PV Estates is socked in by fog, the fog typically stops right at the Terranea Resort in Rancho Palos Verdes, and Portuguese Bend is sitting in the sun. It seems that the ocean side of the Peninsula has had less fog in recent years than many before.

I've generally found the Rolling Hills Estates side to be about 10 degrees warmer than Manhattan Beach, for example, and about 15 degrees warmer than Palos Verdes Estates. The fog tends to hit PVE first, then Manhattan Beach, and rarely comes to the "far side" of the hill. It is common in the summer for RHE to be in the mid-80's to 90 and not unknown to go into the high 90's or even the century mark. This also means it is generally more mild in the winter, frequently sunny on this side while PVE is gloomy and overcast.