Melbourne is bracing for flooding as a huge storm moves across the state, with falls of 50 milimetres in the city's north-east suburbs likely on Saturday morning.

Hundreds of homes have been evacuated in southern California as heavy rains and wind lash the drought-stricken area.

Santa looks set to bring Melburnians a mild and mostly sunny Christmas Day.

Slow-moving Typhoon Hagupit has weakened as it churns across the central Philippines islands, easing fears of widespread mass destruction, but officials warn the storm could still bring severe flooding to the low-lying capital Manila.

"Mate, I lost about 100 heartbeats I reckon in that split second, and got a few more grey hairs."