A spokesman for the centre has told BBC Sinhala Service that this is due to more downpours being forecast tonight and tomorrow.
Floodwaters are receding in most areas, but even scattered showers could trigger landslides, he said.
Meanwhile, the Met Department forecasts rains tonight too, due to the effect of the ‘Mora’ cyclone.
According to the Irrigation Department, water levels of rivers could change as well if more rains occur.
Its directress Prema Hettiarachchi said people living in low-lying areas near rivers should remain vigilant about rising water levels.
RDA hotlines to report damaged roads
Meanwhile, the Road Development Authority has introduced 1968 and 1969 telephone numbers to report about roads damaged by the inclement weather.
Military spokesman Brig. Roshan Seneviratne says that members of the three armed forces continue the rescue and relief operations.
The Navy will begin cleaning drinking wells after the floodwaters recede, said Commander Janaka Samaranayake.
Death toll is 177
Meanwhile, the Disaster Mangement Centre reports that the death toll from inclement-weather related incidents has risen to 177, while 102 are remain missing.
It said 471,542 are affected and 75,236 remain in 336 safe shelters.