The Tanzania Meteorological Agency (TMA) says an incoming storm may impact the Dar es Salaam region.
A heavy rainfall warning has been issued for Lindi, Mtwara, Ruvuma, Njombe, Iringa, Mbeya and Rukwa regions on January 19 and 20.
The TMA says the rainfall may spread to Morogoro, Pwani and Dar es Salaam regions.
Over 50mm of rain are expected to fall in 24 hours.
Seventy homes in Dodoma were reportedly washed away by floodwaters on Sunday night, leaving hundreds homeless, ITV reports.
Residents are advised to take necessary precautions.
Read more: Rainy season ‘fury & destruction’ likely
Editor’s Note: updated on January 19 at 12:25 to correct the date.