Be aware that the forecast can and will be amended if significant changes in the meteorological situation occur to justify changing the forecast.
The amended forecast is immediately transmitted to the media ... but you may never be informed of it because...
The radio or TV station is not "scheduled" to broadcast the weather forecast information when the amended forecast reaches them!
You are either away at work or otherwise busy and not listening to the radio or watching TV!
Really the surest way of being informed of any changes in the forecast is to listen to WeatheRadio Canada which broadcasts (continuously) the very latest:
weather observations,
weather forecasts,
advisories, weather watches or warnings.
Of course, being constantly listening to your Weather Radio receiver may not be practical either! At least, you now know how weather forecasts are made available to you!
Just remember that future weather predictions or forecasts do not exist. There is only the latest valid forecast. The others are obsolete!