W/o looking at any actual research on Jan-Feb temps in So Cal, as a 42 year resident I'd guess Jan is actually a bit warmer and less rainy than Feb, on average, and with either one you have a pretty decent chance of good weather. In the last 6 weeks, my sons have played in the sprinklers in swim trunks and t-shirts several times; plenty of days have been high 60's to mid-70's, with some even warmer (those were in Jan). I love Jan here!