Warmer air helps water evaporate more quickly. But warmer air also holds more moisture, so rainstorms drop more rain. In general, these effects will happen in different places. Wetter places will be wetter still; drier places will become more dry. The map shows the amount of rain that has fallen in California over the past few days.
This despite a series of heavy storms at the end of December. One reservoir was at or over historic levels in December; five are now. But 12 are not, and reservoirs are being replenished rapidly.