Smoke is a downwind problem, and downwind can be a long way. On mistral or tramontane days (the dominant NW winds of the Med arc), plumes stream south-east — so a fire in the Corbières hills hazes Narbonne's beaches, and an inland Provence fire can smoke out the coast 30–50 km away while the town next to the flames stays clear. When the wind flips, so does the problem.
Long-range drift is real. On 25 July, people across the Aude reported a burnt smell with no local fire — the smoke had carried from the Gironde and Landes fires, roughly 300 km away. Don't use your nose to judge distance from danger; use the live fire map.
Nights are worse than days. Smoke settles into valley floors and basins after dark — the Étang de Berre bowl, the Argens valley behind Fréjus, and river gorges generally. If a fire is anywhere in your region, sleep on the coast or on high ground, not in a valley bottom.
Practical rule for van life: if you can see or smell smoke, close vents and windows, skip outdoor cooking, and check the air-quality map before deciding whether to move — driving into a plume on a motorway is worse than sitting tight in light haze.