3am:The San Luis Obispo, CA forecast for Apr 14 is 49 degrees and Clear. There is 70 percentage chance of rain and 8 mph winds from the North. 6am:The San Luis Obispo, CA forecast for Apr 14 is 49 degrees and Clear. There is 64 percentage chance of rain and 9 mph winds from the North. 9am:The San Luis Obispo, CA forecast for Apr 14 is 55 degrees and Partly cloudy. There is 55 percentage chance of rain and 10 mph winds from the North-Northeast.