"The Eyes & Ears of Environment Canada"

CANWARN is a volunteer organization of ham radio operators who report severe weather to Environment Canada. They confirm on the ground what satellites and radar see in the atmosphere.

When Environment Canada's weather centres issue severe weather watches or warnings, they alert the CANWARN volunteers at the organizations regional stations in the affected areas. The volunteers contact other CANWARN members on amateur radio, tell them a watch or warning has been issued and are asked to report signs of approaching severe weather. These include lightning, hail, cumulonimbus clouds and funnel clouds, which if they touch down are then called tornadoes.
For information about CANWARN  please send an email to:
Warning Preparedness Meteorologist, Ontario Region Client Services
Environment Canada, Government of Canada
4905 Dufferin St., Toronto, ON M3H 5T4


Environment Canadas severe weather meteorologists have a variety of tools at their disposal to detect and track thunderstorm activity. These tools include Doppler weather radar, satellite imagery and a lightning detection network. These tools can provide the meteorologists with a good sense of which storms may produce damaging weather like large hail, violent winds, flooding rains or tornadoes. However, these tools do not necessarily provide the meteorologist with a sense of what may be happening right at ground level. Therefore, real-time, on-the-ground information from trained spotters continues to be an integral part of Environment Canadas Severe Weather Watch and Warning Program.

CANWARN volunteers are trained to look for clues in the sky as to which storms may produce damaging weather. They can also report important information on hail size and any damage that has resulted from the passage of a storm. They can send in their reports directly to the Ontario Storm Prediction Centre through an unlisted, toll-free phone number or by a special email address. Both the phone number and email address are monitored 24/7 by meteorologists. Reports received by CANWARN volunteers are often key in the decision to issue or update a warning bulletin for a given area and specific mention is often made of the type of information received by a storm spotter within the text of the warning bulletin.

CANWARN volunteers come from all walks of life; amateur radio operators, the Canadian Red Cross, first responders, municipal/provincial/federal government employees, teachers and many others. Environment Canada holds a series of training sessions across the province each spring to refresh the knowledge of existing volunteers and to welcome new
volunteers to the program. The training normally lasts about 21/2 hours and there is no cost to attend. The training covers the basics of thunderstorm formation, what differentiates a severe from a non-severe thunderstorm, the types of damage severe thunderstorms can produce, what to watch for in the sky, what to report to the Storm Prediction Centre and a series of safety tips.

Environment Canada trains ham radio operators to spot and report severe weather. They learn about the structure of storms, the types of clouds to watch for and what the department's severe weather watches and warnings mean. All CANWARN volunteers are encouraged to sign up for the refresher courses which the department offers each year. Any licenced ham radio operator may become a CANWARN volunteer. Men and women who are studying for their licences or are listeners of short wave radios may join CANWARN as associate volunteers.

Reporting Tip Sheet

How to Report
Amateur radio network (if applicable) 

Amateur Radio Condition Codes:
Green - Severe Thunderstorm Watch
Yellow - Severe Thunderstorm Warning or Tornado Watch
Red - Tornado Warning

Email at



Twitter with hashtag #ONstorm
By phone at 1-800-444-WARN (9276)

What Your Report Should Contain
Who - your name, CANWARN ID, contact number
Where - your location and approx. location of what you are reporting
What - describe what are witnessing/what you witnessed
When - time of occurrence of event and duration
Movement - where phenomenon came from and where it is going
Confidence level

What to Report - Spring/Summer
Large Hail (use coins to describe size ie: nickel, quarter, loonie for larger hail, golf ball etc..)
Heavy rain that has resulted in local flooding
Damaging winds (damage from tree branches down to more significant tree or structural damage)
Funnel Cloud
Dense fog - visibility less than 1 km

What to Report - Fall/Winter
Dense fog - visibility less than 1 km
Any occurrence of freezing rain or freezing drizzle
Heavily accumulating snow (2 or more cm/hr)
Whiteout conditions in snow/blowing snow (visibility near zero)
Rapid freezing of water on road surfaces


The Georgian Bay Amateur Radio Club