Weather Ontario Canada: the official Ontario Canada local forecasts are issued by Environment Canada. The forecasts are "boiled down" to a simple graphic representation for a quick glance (below) at what's most significant to mention in the forecast.
This link gives you access to the very latest version of the complete and official forecast for every region of Ontario.
These forecasts - both short-term and longer term - are constantly monitored by meteorologists and updated or amended when required.
All official forecasts issued by Environment Canada in Ontario reflect the constant flow of incoming weather observations from...
When an observation from any one of the above sources indicates to the meteorologists that the forecast, as issued, needs to be amended...
Meteorologists observe a number of very strict and significant criteria and thresholds to decide whether to amend a forecast before the next scheduled issue. (Forecasts are normally scheduled to be issued every six hours).
There are many reasons that explain why the amendment criteria and thresholds must be significant.
One reason is that most people will not be aware that the forecast has been amended! Why? Because most people are at work or busy doing something else. They are likely not listening to the commercial radio and TV broadcast stations. Even when the commercial broadcasting stations receive the amended forecast, they do not or would not interrupt they regular programming to air the new forecast . . . unless of course there is immediate danger to life and property (such as a tornado alert, for example!).
The best way to be immediately alerted of a significant change in the forecast for your area is to monitor your local Weather Radio Canada station.
NOTE: The local forecasts in graphical form above may be misleading. They only only depict what is most significant in the forecast. They do not give the complete "picture" (pun intended! ;-).
For the detailed forecast for any area in Ontario, click here.