Chatham-Kent had some thundersnow on Wednesday during the latest snow storm.
Environment Canada Warning Preparedness Meteorologist Geoff Coulson told CK News Today thundersnow is not rare, but it doesn't happen very often.
If you heard it but didn't see it, you weren't alone.
Coulson said thundersnow is caused by the same conditions that cause thunderstorms in the summer. He said moisture in an unstable atmosphere causes thundersnow, but the thundersnow in the Chatham area on Wednesday didn't come with a lot of lightning.
"We need a lot of moisture in the low levels of the atmosphere, a fairly unstable atmosphere, meaning the air is going to really want to rise quickly and then a lifting mechanism, something to get the whole process going and move those air masses upwards in the atmosphere. We certainly have all of those ingredients coming together with this low pressure system, especially near the low pressure system," said Coulson. "Chatham-Kent finds itself right on that battle line between those two air masses. Lots of moisture in the atmosphere, lots of instability, and certainly huge amounts of lift with this cold front that is going through."
Coulson said people can hear the thunder but can't necessarily see the lightning because the lightning is going from cloud to cloud or even occurring in-cloud and not striking the ground.
He noted the same risk applies to thundersnow that applies with thunderstorms and people should seek shelter when they hear thundersnow because some lightning strikes could come down.
"What's kind of interesting is that it doesn't often produce a lot of lightning. We know we need the lightning to hear the thunder because we need one before we get the other. Looking at the lightning detection systems of a couple of places, there really isn't a lot of lightning showing up," he said.
Coulson noted southwestern Ontario is favourable for thundersnow because of the cold front coming from northern Ontario clashing with warmer air from the U.S.
There were also several reports of thundersnow in many places across southern Ontario.
He also said the winter temperature is set to return to seasonal levels or even colder in late January and early February.