Swiss Hydro Faces Prolonged Alpine Drought With Only Brief August Relief Ahead
Montel reports temporary rainfall may ease Swiss output through late August, but a 26% generation deficit and record-low Italian reservoirs keep Central European supply stretched.
ICE Endex TTF front-month gas shed 2.65% to €66.50/MWh by the August 25 close, even as Alpine hydropower conditions offered no material improvement to justify the move lower. THE M+1 tracked in the same direction, closing at €67.31/MWh that session. The hydro picture across Switzerland, Austria and Italy remains acutely strained.4
Montel reported on August 21 (2026-08-21) that Swiss hydro is set to receive some drought relief — but explicitly flagged it as temporary. That framing matters for anyone pricing autumn positions on the assumption that late-August rainfall marks a turning point rather than a brief interruption in an ongoing supply deficit.4
The scale of the shortfall is not minor. Run-of-river hydropower generation in Austria and Switzerland has fallen 46% and 26%, respectively, from last summer's levels, while Italian reservoirs have reached a record low, according to Montel analysis published August 13 (2026-08-13). Three countries simultaneously depleted.3
Switzerland's National Drought Platform said late on Thursday (2026-08-06) that extreme drought conditions were likely to persist well into August, with relief only visible in the second half of the month. The language stopped well short of a recovery call. No improvement was visible in the first half of August, the platform said.1
Italy's situation had already forced an earlier intervention. Switzerland released water reserves to address what Montel described on August 12 (2026-08-12) as an "unprecedented Italy hydro crisis," partly drawing down Swiss storage before the forecast rainfall window even opened. That draw-down is not easily replenished by a brief rainfall spell.2
Italy is a net power importer under normal conditions. When its own reservoir storage hits record lows simultaneously with run-of-river output across Austria and Switzerland running nearly half below year-ago levels, the import demand radiating out across the wider European grid compounds pressure on systems that are themselves stretched.3
The gas switching arithmetic runs in one direction under these conditions. Lower Alpine hydro availability forces Italy and other Central European consumers to burn more gas to cover the generation gap. That dynamic sustains TTF demand even when the ICE Endex TTF front-month headline price slides. The August 25 drop came against a backdrop of hydro stress, not because of any easing in it.3,4
Brief rainfall replenishes run-of-river flows faster than it restores large reservoir storage. That distinction is consequential for how durable any August hydro recovery proves. Switzerland's 26% output deficit against last summer, and Austria's 46% deficit, represent a substantial hole in Central European generation capacity that days of rainfall cannot close.3
The Montel reporting from August 21 (2026-08-21) describes the incoming rainfall window as real but limited in duration — enough to ease the most acute pressure, insufficient to reset the underlying deficit that has accumulated since early summer. Swiss reservoir levels after the rainfall window closes, and whether Italian storage recovers meaningfully before autumn demand picks up, are the two variables that will matter most for how the region enters the September demand season.4,3
Italian reservoir levels are the data point carrying the most weight into September. If they remain near record lows after the temporary Swiss relief passes, the Alpine hydro system enters autumn with less cushion than gas and power forward curves have typically priced for this time of year.3,4