This is Lake Miramar, just to the east of La Jolla near San Diego.
I went out for a run today. When I left the hotel, it was overcast and dull. By the time I reached the lake it was a little warmer, but not too bad. But by the time I got about three miles into the run, the clouds had gone and the temperature had soared. I had to walk for about a mile. Luckily, the weather calmed down a little and I eventually managed to complete two laps – around ten miles – but it was still warm, as you can see from the picture!