Much-need rain has begun to fall over Southern California, bringing relief to the drought-stricken region but also the threat of toxic runoff.

Southern California’s first full rainy day of the winter has arrived. The day, months in the making, has brought steady storms across the region while the Southland experiences drought conditions. The mostly welcome rain began Saturday night and is expected to sustain until Monday evening.

Rain brought much needed aid to the Los Angeles firefight, moving the fires surrounding the city closer to containment.