Foggy start to the week across parts of Southern Ontario
Monday, May 28, 2025 — Ottawa, Ontario – A weather advisory is currently in effect across portions of Southern Ontario, where dense fog is creating dangerous travel conditions, especially north and west of the Greater Toronto Area (GTA).
Although the rainfall has ceased and skies are beginning to clear, residual moisture and overnight cooling have contributed to the formation of thick fog banks early this morning. According to Environment and Climate Change Canada, significant fog development has been observed in areas surrounding London and extending into Cottage Country.
Visibility concerns and travel risks
The advisory highlights that visibility may suddenly drop to near-zero in affected areas. These fog patches are particularly treacherous for morning commuters, and drivers are being warned that travel may be hazardous due to the drastically reduced visibility in specific locations.
Environment Canada urges anyone on the roads this morning to be prepared for unpredictable and rapidly changing visibility conditions. Areas under the fog advisory were shaded grey on meteorological maps released early Monday.
The fog is expected to lift later this morning as temperatures rise and winds pick up, helping to dissipate the trapped low-level moisture. However, until then, extreme caution is urged, particularly on rural highways, open fields, and low-lying areas where fog tends to linger longer.
Geographic focus and visibility risks
Primary zones impacted include the region around London, western periphery of the GTA, and cottage-heavy districts across Southern Ontario. These areas are prone to rapid fog formation, especially following wet weather and calm overnight conditions—a classic setup for morning fog events.
The advisory remains in effect throughout the early morning hours, with conditions improving by midday as the fog burns off.
Stay tuned to local forecasts and environmental bulletins for updated information as the situation evolves across Southern Ontario.
