A flood watch has been issued for areas along the Nith River in New Hamburg and Ayr, and conservation officials say other local rivers will also see increased water levels.
The Grand River Conservation Authority says heavy rain combined by high temperatures causing snow to melt are leading to significant jumps in water levels across the Grand River watershed.
Along the Nith river, water levels could reach flood thresholds.
In New Hamburg, the GRCA says residents in the Milton Street and Jacob Street areas could be affected by rising water levels, which are expected to peak early Thursday morning.
In Ayr, residents along Piper Street and Tanner Street may be affected by flooding, with the Nith peaking there around noon on Thursday.
Residents in both areas are advised not to park cars in low-lying areas overnight.
Flooding is also anticipated in low-lying areas around the Grand, Speed and Conestogo rivers, the GRCA says, with runoff from the northern portions of the Grand River watershed flowing downstream.
Water levels along those rivers are expected to remain high through the weekend.
