Canadian forest fires bring grey skies and red sunsets to Switzerland

If you look to the skies and see that the azure blue has gone a paler shade of grey, you may assume that Saharan dust has once again arrived in Switzerland. However, this week the murky weather has not been caused by a vast desert across the Mediterranean, but by forest fires more than 7.000 kilometres away.

Blue skies turn light grey across Switzerland

As Switzerland begins to be gripped by a short and sharp heatwave, MeteoSwiss has confirmed that recent days have seen the rise of grey conditions and pale skies both in cities and the mountains. Heightened levels of particulate matter and air pollution have also been detected in the Alps.

This phenomenon has defied forecasts, which originally assumed that Whit Monday would see bright blue skies across Switzerland. However, instead of the traditional culprit - particles from the Saharan desert - meteorologists noted the cause is actually fires from across the Atlantic Ocean.

What's causing the murky conditions across the cantons?

According to SRF Meteo, since the end of May, Europe has experienced a wave of smoke particles from forest fires in Canada. Starting in mid-May, overly dry conditions have caused severe forest fires in the provinces of Manitoba, Ontario and Saskatchewan. 

The Canadian Interagency Forest Fire Centre estimates that 1.896 forest fires have occurred between May 2025 and June 11, torching 8,4 million acres of forest. Now, thanks to the jet stream, smoke has been sent high into the atmosphere and up to 7.000 kilometres across the Atlantic to Europe. This smoke has now blanketed the continent, blocking out the sun in the Azores and reaching Greece at the end of May.

What impact does the Canadian forest fire smoke have?

The first waves of smoke arrived in Switzerland last week, but went unnoticed due to the heavy rainfall at the time. Now, with the weather improving and the clouds parting, you’ll notice that the skies will still look a little grey, and the nights may include reddish sunsets, which on June 11 will be made all the more spectacular by the Strawberry Full Moon.

Although the smoke has no direct impact on health, it will reduce air quality across Switzerland. This may affect those with asthma or hay fever. With the Canadian forest fires still ongoing, this phenomenon could remain for some time, at least until it rains.