CANWARN – Environment Canada

CANWARN is a volunteer organization of ham radio operators who report severe weather when they see it to Environment Canada. What they do is called ground-truthing. They confirm on the ground what satellites and radars see in the atmosphere. When Environment Canada’s weather centres issue severe weather watches or warnings, they alert the CANWARN volunteers at the organization’s regional stations in the affected areas. The volunteers contact other members on the ham radio, tell them a watch or warning has been issued and ask them to report signs of approaching severe weather. These include lightning, hail, cumulonimbus clouds or as they are known in the trade CBs, and funnel clouds, which if they touch down are then called tornadoes.


CANWARN is organised in local networks. When members spot severe weather, they send their reports to the network controller who forwards them to Environment Canada’s severe weather office in Toronto using either a special telephone line or the web page. At the weather office, the severe weather meteorologist combines the data from the satellites and radar with the information from the ground to refine the forecast or prepare a severe weather watch or warning. In Ontario, stations are equipped with computers, printers, and ham radio equipment, and are located in community centres such as airports, police stations and senior citizens complexes.


Ham or amateur radio operators have long played important roles in their communities, particularly during emergencies. These men and women run very high frequency, VHF, or ultra high frequency, UHF, radios from their homes, offices, cars or trucks and so are in a good position to help when normal lines of communication have been knocked out by a tornado, fire or explosion.

Their roles expanded after the Edmonton tornado on July 31, 1987. The tornado which had winds of more than 400 kilometres an hour ploughed through the Alberta city in the mid afternoon killing 27 people, injuring 253 others and causing more than $250 million in damage. The report on the Edmonton tornado and the weather warning system, known informally as the Hage report, said Environment Canada should solicit the help of amateur radio operators in the severe weather watch and warning program.

Within a week of the report’s publication, Environment Canada had trained more than 120 ham radio operators in the Windsor area to detect severe weather. At first CANWARN, operated primarily in southwestern Ontario. Today, there are CANWARN stations in towns and cities from Windsor through to eastern Ontario and Parry Sound on Georgian Bay. There are also CANWARN stations in Northwestern Ontario, including places like Thunder Bay, Fort Frances, Dryden, and Kenora. Volunteers cover most of the areas of Ontario that are likely to have severe weather. CANWARN is active (to varying degrees) in Manitoba, Saskatchewan and Alberta.

Environment Canada

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 volunteer. Men and women who are studying for their licences or are listeners of short wave radios may join as associate volunteers.

For information about CANWARN  please send an email to: or visit

2017 Training Dates and Locations

April 5 – Owen Sound – 6:30 PM Quality Inn, 950 6th St E, Owen Sound, RSVP to
April 18 – Windsor – 7 PM Caboto Club, 2175 Parent Ave
April 19 – Sarnia – 7 PM Sarnia Yacht Club, 1220 Fort St RSVP to Bill Hoad
April 20 – London – 7 PM Fanshawe College, 1001 Fanshawe College Blvd, Building T Room T1003
April 24 – Central Huron/Blyth – 7 PM Emergency Services Training Centre, 40193 Blyth Road, Central Huron/Blyth
April 25 – Stratford – 7 PM – Perth County Paramedic HQ, 480 Douro St, Stratford RSVP to
April 29 – Barrie – 9 AM Innisfil IdeaLab and Library, Community Room, 967 Innisfil Beach Road
May 3 – Brantford – 7 PM 3rd Floor Atrium Room, Brantford Public Library, 173 Colborne St.
May 6 – Toronto – 9 AM Environment and Climate Change Canada HQ, 4905 Dufferin St.
May 8 – Niagara Region – 7 PM Niagara Region HQ, Council Chambers, 1815 Sir Isaac Brock Way, Thorold
May 9 – Dufferin County – 7 PM Dufferin County Courthouse, 55 Zina St., Orangeville
May 10 – Waterloo – 7 PM RIM Park 2001 University Ave East, Waterloo
May 13 – Hamilton – 9:30 AM Stoney Creek City Hall, 777 Highway 8, Stoney Creek
May 15 – Peterborough – 7 PM Peterborough Lawn Bowling Club, 577 McDonnel St.
May 16 – Ottawa – 6:30 PM – Greenboro Community Centre, 363 Lorry Greenberg Dr., Ottawa
May 16 – Toronto – 7 PM – Environment and Climate Change Canada HQ, 4905 Dufferin St
May 17 – Cornwall – 6:30 PM – Cornwall Public Library, 45 Second St. E, Cornwall
May 18 – Tiverton – 7 PM Bruce Power Visitor Centre
May 24 – Markham – 7 PM Canada Room Markham Civic Centre, 101 Town Centre Blvd, Markham
May 25 – Oakville – 7 PM Glenorchy-Dakota Room, Halton Region HQ, 1151 Bronte Rd, Oakville
May 27 – Belleville – 9:30 AM Belleville Public Library Conference Room, 254 Pinnacle St.
May 29 – Sudbury – 6:30 PM Lionel E. Lalonde Centre, Azilda
May 30 – Espanola – 7 PM Pinewood Inn Espanola May 31 – Sault Ste Marie TBA
June 5 – North Bay – 6:30 PM OPP Regional HQ Cahty Burns Training Room, 911A Gormanville Road
June 6 – Temiskaming Shores – 6:30 PM – College Boreal, New Liskeard
June 7 – Timmins – 6:30 PM – Timmins Firehall, 133 Cedar St. June 12 – Thunder Bay – TBA
June 13 – Fort Frances/Emo – TBA
June 13 – Renfrew – 6:30 PM Days Inn, 760 Gibbons Rd, Renfrew
June 14 – Kenora – TBA
June 15 – Dryden – Dryden Fire Services Training Room 189 Colonization Ave S