Snowmobile clubs and volunteers are under no legal obligation to place any signs on snowmobile trails, but do so as a courtesy and convenience, to provide visual assistance for riders who take the personal responsibility to operate their sleds within the law and with care and control. Any signage provided by the OFSC for the convenience of prudent snowmobilers is never a substitute for rider knowledge, choice or vigilance. OFSC signage continues to remind riders that snowmobiling is an inherently risky activity that each individual chooses to participate in of their own free will and at their sole risk.
RED - Significant Warning. Failure to obey may result in personal injury or death.
The following are some of the signs riders may see on trails and their meaning:
USE TRAIL AT YOUR OWN RISK
YOU must know and obey the Motorized Snow Vehicles Act (Ont.)
YOU must use caution at all times
Emergency and cell phone service may not be available
The law says that snowmobiles must stop at all road crossings, regardless of whether a STOP sign is present or not.
YELLOW - Back off the throttle and prepare to take corrective action.
Directional Arrow
Stop Ahead
Slow down
Railroad Crossing
Bridge Hazard Markers
Ice Crossing - Use at your own risk
Informational:
The maximum legal trail speed limit in Ontario unless otherwise posted.
No Trespassing Sign. Snowmobilers are permitted to use the trail with a trail permit.
Prescribed Trail Sign: This sign tells riders that they are on an OFSC prescribed trail. Trail permits are required to ride on OFSC prescribed trails.
The law says that snowmobiles must stop at all road crossings, regardless of whether a STOP sign is present or not. 
Directional Arrow
Stop Ahead
Slow down
Railroad Crossing
Bridge Hazard Markers
Ice Crossing - Use at your own risk
The maximum legal trail speed limit in Ontario unless otherwise posted.
No Trespassing Sign. Snowmobilers are permitted to use the trail with a trail permit. 
Prescribed Trail Sign: This sign tells riders that they are on an OFSC prescribed trail. Trail permits are required to ride on OFSC prescribed trails. 