The system will allow Canadians to better prepare their day-to-day lives, Environment Minister Leona Aglukkaq told a news conference in Montreal on Tuesday.
"The weather affects how we travel, conduct our business, build our homes and (plan) our recreational activities," she said.
"And, most importantly, our weather forecasts warn Canadians about potentially life-threatening hazards such as tornadoes, thunderstorms and extreme cold."
Steve Ladurantaye, Twitter Canada's head of news and government partnerships, called it the first system of its kind in the world.
The service is available for some 830 communities across the country.
Environment Canada estimates a total of about 25,000 tweets will be sent out every year — whenever an alert is issued or lifted.
Asked whether the government had conducted any studies to assess the usefulness of the new service, Conservative MP Jacques Gourde replied: "If I just take the example of my own children, Facebook, Twitter, that's their kind of reality."