FOCA offers numerous resources on all subjects related to living on the water including:
Winter safety
Boating and Cold Water Immersion

Ice Safety   
Many factors affect ice thickness.  For information on Ice Safety click on this Red Cross link.

Cold Temperatures
From Health Canada:
Extreme Cold 

From the Red Cross website:
Hypothermia and Cold Water from the Red Cross website
Cold Related Emergencies 

Off-Road Vehicles and Snowmobile Safety  
Off-Road Vehicles and Snowmobiles by the Ministry of Transportation (MTO)
Snowmobile Safety by the MTO
Rules of the Road for Safe Snowmobiling by the Ontario Federation of Snowmobile Cubs (OFSC)
Snowmobile Permits by the OFSC