Summer returns to Switzerland: Temperatures up to 28°C at the end of September

GlobalTalent24 Team

Autumn has officially arrived, but summer in Switzerland has not yet said its last word. According to the SRF Meteo forecast, from Sunday through Wednesday the Swiss Plateau is expected to see daytime highs of 26°C to locally 28°C. That is around ten degrees above what is usual for this time of year.

For people living in Switzerland, this means several almost summery days right at the end of September. Sunshine and high temperatures will offer an excellent opportunity to spend time outdoors, but behind the pleasant weather picture lies another side of the story: large parts of the country have been feeling the effects of pronounced drought and a lack of rainfall for months.

Switzerland weather forecast: Up to 28°C at the end of September

According to the SRF Meteo meteorological analysis published on 24 September, temperatures on Sunday should reach around 26°C on the Swiss Plateau, while local values of 28°C are possible at the beginning of the following week.

For late September, these are unusually high values. SRF Meteo says temperatures will be roughly ten degrees above the climatic norm.

This, of course, does not mean that all of Switzerland will experience identical temperatures. Weather in Switzerland depends strongly on elevation, position relative to the Alps, fog, wind and local cloud cover. Conditions can therefore differ considerably from one region to another.

Why is it so warm in Switzerland again?

A stable high-pressure weather pattern lies behind the unusually warm end to September.

According to SRF Meteo, very dry soil also plays an important role. When the soil contains enough moisture, part of the Sun’s energy is used to evaporate water. When the ground is dry, a larger share of that energy directly heats the surface and the air above it.

The combination of sunny weather, high pressure and dry soil can therefore push daytime temperatures even higher.

The nights do not necessarily have to be equally warm. Clear skies allow the ground to lose heat more quickly overnight, so the difference between daytime highs and nighttime temperatures can be quite pronounced.

September temperatures in Switzerland well above average

The warm end to the month is not an isolated event. September 2026 has so far been exceptionally sunny, dry and warm.

On 22 September, citing meteorological data, SRF reported that the month up to that point had been approximately three to five degrees warmer than usual. Across large parts of the country, only around 10 to 20 percent of the usual September rainfall had fallen.

Another spell of exceptionally high temperatures had already occurred at the beginning of September, when values of up to 30°C were expected in some parts of the country.

As a result, this September in Switzerland has repeatedly felt more like an extension of summer than the beginning of a typical autumn.

Regional weather differences in Switzerland

When discussing weather in Switzerland, the national average often does not tell the whole story.

The Alps strongly influence the country’s climate, so temperature, rainfall and cloud cover can differ significantly between the northern and southern sides of the Alps, higher mountain areas and the Swiss Plateau.

MeteoSwiss states that Switzerland’s climate is strongly shaped by the Alps and the influence of the Atlantic. Because of the terrain, substantial regional climate differences exist within a relatively small area.

The forecast of 26 to 28°C should therefore be understood primarily in the context of lower elevations and the Swiss Plateau, rather than as a temperature that will apply to every location in the country.

Behind the sunshine, drought remains a serious problem

For excursions, walks and outdoor activities, the warm weather can be very pleasant. For nature, however, the continuation of the dry period is not equally good news.

The Federal Office for the Environment, BAFU, states in a report published on 23 September that pronounced drought, particularly on the Swiss Plateau, has persisted since spring 2026. Rainfall was significantly below the long-term average, while temperatures were often above usual seasonal values.

The consequences can be seen in dry soils, low river levels, low groundwater levels and reduced discharge from some springs.

Short periods of rain can quickly change conditions in the surface layer of the soil or in smaller streams. However, BAFU stresses that deeper soil layers, groundwater and springs need much more time to recover. A more lasting improvement requires longer-lasting and more widespread rainfall.

Nearly 40 percent of monitoring stations recorded new lows

The scale of the drought is best seen in data from Swiss rivers.

According to BAFU, between 1 June and the end of August 2026, nearly 40 percent of Swiss monitoring stations recorded a new record-low flow for that period of the year.

The situation was particularly pronounced in the central and eastern Swiss Plateau, the Pre-Alpine regions and Graubünden.

On the northern side of the Alps, many rivers continue to have low water levels. BAFU also states that occasional rainfall and storms during recent weeks have not been sufficient for a lasting recovery.

High temperatures also affected Swiss rivers

The amount of water is not the only problem.

During summer 2026, temperatures in numerous rivers reached very high levels. BAFU states that between the beginning of June and the end of August, almost 60 percent of the monitored stations recorded new maximum water temperatures for that period.

At some locations, previous records were also broken. The Aare near Bern reached 24.8°C on 14 July, while the Reuss near Lucerne reached 26.36°C on 27 June.

High water temperatures can place additional stress on fish and other aquatic organisms, particularly when combined with low flows.

Climate change in Switzerland: What does the long-term trend show?

One warm weekend or several days at 28°C are not, by themselves, proof of long-term climate change. Weather and climate are not the same thing.

Climate trends are assessed using long measurement series. It is there that official data show the broader picture.

BAFU states that climate scenarios for Switzerland indicate an increase in periods of heat and that longer drought episodes, as a consequence of climate warming, are expected to become more frequent in the future.

Changes are also visible in the water. According to BAFU, the temperature of the Rhine near Basel has risen by more than two degrees Celsius since the 1960s, and a similar trend has been observed in other waterways on the Swiss Plateau.

The current 26 to 28°C at the end of September should therefore be viewed as a weather event, while the question of climate change is assessed over a much longer period.

Weather phenomena in Switzerland are becoming an increasingly important topic

Because of its geographical position and the Alps, Switzerland has always had large regional differences and interesting weather phenomena. Föhn winds, fog on the Swiss Plateau, heavy precipitation on the southern side of the Alps and large temperature differences between lowlands and mountains are part of the country’s characteristic weather pattern.

Nevertheless, extreme heat and prolonged drought have increasingly become a focus for meteorological and environmental services in recent years.

Summer 2026 was particularly striking because of the combination of high temperatures and a lack of rainfall. Several additional summer-like days at the end of September therefore arrive at a time when nature, especially in parts of the Swiss Plateau, needs a longer period of steady rainfall.

What can we expect in the coming days?

The short-term weather forecast for Switzerland brings several more very warm days.

On the Swiss Plateau, around 26°C is expected from Sunday through Wednesday, with local values of 28°C possible. For the end of September, this means weather that will feel much more like summer than autumn.

However, local forecasts can change, and temperatures will depend on the region and elevation. When planning travel, excursions or outdoor activities, it is advisable to check the latest local forecast immediately before setting out.

Switzerland is therefore ending September in an unusual contrast: almost summer on the thermometer, autumn on the calendar, while the effects of an exceptionally dry period remain visible in soils and waterways.

Sources

The information in this article is based on data available at the time of publication. Weather forecasts are subject to change. For the latest local weather conditions, forecasts and any warnings, current information from the relevant meteorological services should be checked.

Note on illustrations

Visual materials used with this article may have been generated using artificial intelligence and are provided solely for illustrative purposes. They do not represent authentic photographs of the specific weather event, place or moment described in the text.