You had your Christmas break from the rain, but it arrives back in the city later today, with a not-insignificant three-quarters of an inch set to fall tonight.

While it's been a gloomy day overall in San Francisco, with clouds threatening to produce rain, we haven't seen any of it yet. As the Chronicle meteorology team tells us, though, that should change by 5 pm Thursday, with rain spreading down from the North Bay in our direction.

The weather system, the team says, is "relatively disorganized," so it's not clear when the heaviest bouts of rain will hit the city. But expect periods of heavy rain Thursday night, with the downpours not really tapering off until early Friday.

San Francisco and Oakland may even experience some urban flooding, as the heaviest rains might accumulate quickly.

This is also going to make for a terrible day to be driving up to the Sierra, if that was part of your plans. Light snow is expected to get heavier this afternoon, which could create some hazardous driving conditions into the Tahoe area, and some high wind gusts up to 45 miles per hour as well.

Friday will be dry again, though the chance of preciptation rises again Friday evening and Saturday is expected to be wet once more, possibly confied to just the morning hours.

Forecasters seem to be split about whether Sunday will be rainy or just cloudy, but the sun appears to be returning by Monday and into the new year.

Photo: Nadia Ploshchenko