(The opinions expressed here are those of the author, a columnist for Reuters.)

LITTLETON, Colorado - Europe's wind turbines are set to take over from solar panels as the main driver of clean electricity supply growth for the rest of 2025, as the end of the Northern Hemisphere summer brings less sunlight but windier conditions at turbine level.

So far this year, Europe's wind generation levels have come in well below normal due to lengthy wind droughts, which have led to a rare year-over-year drop in Europe's total clean electricity supplies.

Total European wind-powered electricity supplies from January through August were down 6% from the same months in 2024, data from think tank Ember shows, while total clean electricity supplies were down 2%.

The forecast for European wind power output, however, is positive, with LSEG models calling for a sharp rise in regional wind power output over the second half of September.

If those higher wind generation levels are sustained through the winter - historically an active period for wind output in Europe - Europe's total clean electricity output could still climb to a new record this year.

SEASONAL PEAKS AND TROUGHS

Solar has been the star of Europe's electricity generation system so far in 2025, with solar-powered electricity output up by more than 20% from a year ago to all-time highs.

Solar electricity output in Europe scaled successive record highs in May and June this year, data from Ember shows, as expanded capacity resulted in steadily-higher generation across the continent.

However, solar generation levels have now peaked for the year, with output in July and August both posting declines from the prior month as cloudier skies and less daylight trimmed generation from solar farms.

Thankfully for the clean power advocates, electricity generation from wind farms tends to climb steadily after the summer as the change of seasons ushers in breezier conditions.

The complementary nature of solar and wind generation patterns normally means that Europe's total clean electricity production is quite stable throughout the year, even with the large swings in solar and wind production from summer to winter.

This year, however, the stretch of below-normal wind generation during the opening half of 2025 has raised concerns that output from wind farms will remain stunted for the rest of the year as well, and deal a blow to clean power growth efforts.

WIND'S LETDOWN

Wind speeds across continental and northern Europe during the first half of 2025 averaged around 4% to 8% below long-term averages, according to risk consultancy DNV.

Those below-average wind speeds were especially evident during the opening four months of 2025, when Europe's wind-powered electricity supplies were consistently below the year-before levels.

Wind electricity generation from January through April averaged around 10 terawatt hours (TWh) or 16% lower compared to the same months in 2024, Ember data shows.

Some countries in Europe recorded even steeper falls in wind generation this year, including Germany and the United Kingdom, which are Europe's largest wind power producers by capacity.

Germany's wind electricity output during January to April averaged 30% below the year-before totals, while output in the UK averaged 20% lower.

ON THE RISE?

Wind watchers are closely tracking wind output forecasts for the coming autumn and winter, as any sustained below-par wind generation will likely require regional utilities to boost use of fossil fuels for power and heat generation.

However, the latest forecast models suggest a notable upturn in regional wind generation can be expected over the coming weeks.

Collective wind generation across continental Europe looks set to rise from around 40,000 MWh to 60,000 MWh per day so far in September to roughly 60,000 MWh to 110,000 MWh per day during the second half of the month, LSEG data shows.

Longer-term forecasts also call for sharply higher supply compared to recent levels.

In Germany, wind power output averaged around 10,700 MWh per day in August, but is expected to average around 15,200 MWh in September, nearly 19,000 MWh a day in October, and climb to more than 24,000 MWh a day by December.

In the UK, average output was around 5,100 MWh a day in August, and is set to average around 7,000 MWh in September, 8,500 MWh in October, and rise to around 10,500 MWh per day in December.

If those forecasts hold true, those output levels would be roughly on a par with the long-term average in Germany and roughly 10% above the long-term average in the UK, LSEG data shows.

Those output forecasts would also likely be enough to ensure that Europe's total supplies of clean electricity scale new highs in 2025, despite the early-year dip in wind production.

Any underperformance by wind farms over the coming months, however, would lead to lower overall clean electricity supplies and likely trigger higher fossil fuel generation by utilities during Europe's peak power demand and heating seasons.

The opinions expressed here are those of the author, a columnist for Reuters.

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(Reporting by Gavin Maguire; Editing by Jamie Freed)