Environment Canada has placed a rainfall warning over Cochrane and the surrounding area. 

"Thunderstorms currently developing on the foothills near Calgary will push northeast this evening, and merge into a large area of heavy rain tonight." 

"Total rainfall amounts of 40 to 60 mm are likely to fall in a 12-18 hour period. This rain event will come to an end by late Sunday morning." 

The heavy rain could cause flash floods and water pooling on roads. There is also a chance of localized flooding in low laying areas.