The Durham Thunderstorm Forecast calls for a wet and potentially stormy start to Wednesday as a cold front moves across southern Ontario, bringing showers, thunderstorms and locally heavy rainfall.
Environment Canada’s outlook places all of southern Ontario, including Durham Region, within an area that could experience thunderstorms overnight and through Wednesday morning.
The main concerns for Durham are rainfall and scattered lightning, with local rainfall totals potentially reaching 35 millimetres in areas that receive heavier showers or thunderstorms.
The outlook becomes more varied Wednesday afternoon, when the greatest risk of severe storms shifts farther east toward areas such as Prince Edward County, Kingston and Ottawa.
Durham Region, however, could still experience isolated thunderstorms and additional rainfall later in the day.
Storms Possible Overnight and Wednesday Morning
The first round of unsettled weather is expected ahead of an approaching cold front.
Environment Canada says showers accompanied by a risk of thunderstorms could develop overnight and continue into Wednesday morning across southern Ontario.
Durham Region is included in that broad risk area.
Rainfall amounts will vary considerably depending on where individual thunderstorms develop, but localized totals could reach 35 mm.
Scattered lightning is also possible.
This means some communities could receive only moderate rainfall while others experience significantly heavier downpours over a shorter period.
Durham Could Avoid Strongest Afternoon Storms
The strongest storm risk Wednesday afternoon is currently focused farther east.
Environment Canada identified an area including Prince Edward County and Kingston north toward Ottawa where isolated to scattered thunderstorms could become strong or severe.
Those storms may produce wind gusts reaching 90 km/h, hail up to 2 centimetres in diameter and locally heavy rainfall.
Durham Region is outside the main severe-weather zone described in the supplied outlook.
However, that does not mean the region will remain completely dry after the morning storms.
The broader southern Ontario area could still see isolated or scattered thunderstorms Wednesday afternoon.
Local rainfall amounts outside the strongest storm zone could reach approximately 15 mm.
Up to 35 mm of Rain Could Fall Locally
The biggest concern in the Durham Thunderstorm Forecast is rainfall during the overnight and morning period.
Environment Canada says some locations could receive as much as 35 mm.
Thunderstorms can produce very uneven rainfall totals because heavier rain may fall over a small geographic area.
Residents in one part of Durham could therefore see considerably more precipitation than neighbouring communities.
Drivers should be prepared for reduced visibility and water collecting on roads during heavier downpours.
Areas with poor drainage may also experience temporary ponding if rain falls quickly.
Lightning Also a Concern
Scattered lightning strikes are possible during the morning thunderstorm activity.
Residents should move indoors if thunder is heard nearby and avoid exposed outdoor areas until storms have moved away.
Outdoor workers, commuters and anyone planning morning activities should monitor changing conditions.
Thunderstorms can develop or strengthen quickly, making updated forecasts important even when severe weather is not initially expected.
Severe Storm Risk Focused East of Durham
For Wednesday afternoon, the more significant severe-weather threat is expected from Prince Edward County and Kingston north toward Ottawa.
Storms in that area could potentially bring damaging wind gusts, hail and heavier rainfall.
Environment Canada cautioned that confidence remains low regarding how strong any afternoon thunderstorms will become.
That uncertainty is common with convective weather because small changes in temperature, humidity and atmospheric instability can significantly affect storm development.
Durham residents should therefore continue monitoring forecasts even though the highest afternoon risk is currently east of the region.
Weather Could Improve Behind Cold Front
The unsettled weather is associated with a cold front moving through southern Ontario.
Once that front passes, conditions could become cooler and less humid.
However, the timing of individual showers and thunderstorms may vary across Durham Region.
Residents should check the latest weather information before commuting, travelling or planning outdoor activities Wednesday.
Durham Residents Should Prepare for Wet Roads
The Durham Thunderstorm Forecast does not currently indicate that severe storms are the primary threat locally, but heavy rainfall and lightning could still affect the region.
Motorists should slow down during downpours, leave additional stopping distance and avoid driving through water covering a roadway.
Residents should also secure lightweight outdoor items if stronger winds develop with any thunderstorm.
The most significant period for Durham appears to be overnight through Wednesday morning, when showers and thunderstorms could produce locally up to 35 mm of rain.
Additional isolated thunderstorms remain possible Wednesday afternoon.
