A woman has died after a two-vehicle crash west of London and provincial police say heavy fog in the area was likely a factor.

Middlesex OPP and emergency crews were called to the intersection of Calvert Drive and Thames Road in Middlesex County around 7:30 a.m. on Tuesday.

Investigators say a grey Volkswagen Jetta was northbound on Thames Road when it collided with a van that was eastbound on Calvert Drive.

It appears the woman driving the Jetta, believed to be in her 50s, either didn't see the stop sign or didn't see the van.

OPP Const. Laurie Houghton says "As a result of the collision the female driver was pronounced dead at the scene and the [male] driver of the van was transported to Strathroy General Hospital with non-life-threatening injuries."

Officers arriving at the scene of the crash, which happened just as the sun was coming up, say the fog was so thick they couldn't see anything beyond about 10 metres down the road.

"It was extremely foggy, visibility was poor. We were asking drivers from early on this morning to be careful with your driving, slow down and keep your lighting on," Houghton says.

In fact, the fog was so dense on Tuesday morning it didn't lift until around 9:30 a.m. in some areas, leading to numerous school bus cancellations.

Fog is expected to be heavy in the area again during Wednesday's commute, if not even worse, and drivers are urged to be cautious as similar conditions persist through the week.

The OPP Technical Traffic Collision Investigation team are assisting with the investigation and Calvert Drive between Winter Drive and Burdon Road remained closed for about seven hours.