Greece’s weather turns autumnal from Sunday as rain and storms spread across several regions

Greece’s weather is forecast to turn more autumnal from Sunday, October 11, as a slow-moving pressure system between Italy and Greece brings rain and storms to several regions. The strongest effects are expected in western and northwestern Greece, with unsettled conditions forecast to continue into the start of the following week, according to the forecast.

The recent stretch of relatively summer-like conditions is expected to give way to a more autumnal pattern, with increased cloud cover, rainfall and localized storms. The shift is linked to an atmospheric disturbance lingering over the wider Ionian Sea area, which is moving slowly. Its gradual eastward shift is expected to spread rainfall over a larger part of the country.

Conditions are forecast to remain unsettled through the following week as well, though this does not mean continuous rainfall in all areas. The intensity, extent and duration of the rain will depend on how the atmospheric disturbances evolve, the forecast says.

Sunday rain and storms — where the strongest effects are expected

Sunday, October 11, is expected to be the day when the change in weather becomes most noticeable. Rain and localized storms are forecast for the Ionian islands, several regions of mainland Greece, and the northern and northeastern Aegean.

Particular attention is being drawn to western and northwestern Greece, where conditions could become more intense. Areas with an increased likelihood of heavy rainfall include the northern Ionian, Epirus and western Sterea Ellada.

In northeastern mainland areas and on islands of the eastern and northeastern Aegean, the most significant activity is expected from Sunday night into Monday. Rain in these areas is estimated to continue until around midday on Monday, October 12, before gradually easing.

The role of the pressure system

The behavior of the pressure system located over the Ionian area plays a decisive role in how the weather develops. Its limited speed of movement affects both the timing of the rainfall and its geographic distribution.

Forecasting the exact path of such a system is a complex process, as even small variations in atmospheric circulation can affect the intensity and extent of the phenomena. Modern numerical models allow for an estimate of the most likely outcome, but forecasts remain subject to revision as newer data become available. For this reason, the exact timing of a storm in a specific area, as well as the eventual rainfall total, cannot be determined with absolute precision several days in advance.

Three factors shaping the coming days

Three main atmospheric characteristics are expected to determine weather conditions in the coming days. The first involves thermal instability, which, although more commonly associated with summer months, can also occur in October under the right atmospheric conditions, favoring localized showers and isolated storms over the mainland.

The second factor relates to the disturbance affecting the country on Sunday, which is expected to bring more widespread rain and storms, with activity stronger in the west and northwest before spreading to areas farther east. A further disturbance that follows may maintain limited instability, mainly where other favorable atmospheric factors coincide.

Cold air masses move toward Europe

Also of interest is the broader atmospheric circulation taking shape from Monday, October 12. Jet stream activity over the northeastern Atlantic is expected to contribute to the transport of colder air masses toward central and eastern Europe.

This development is linked to the formation of atmospheric waves affecting air mass circulation on a large geographic scale. In a later phase, the cold air transport may extend toward the Balkan Peninsula, creating conditions for further weather changes. For now, the exact impact of this development on Greece remains under review and will become clearer as newer forecast data emerge.

The main feature of the coming days is expected to be the return of rain to several parts of the country, with Sunday drawing the greatest attention in terms of the intensity and extent of the phenomena. The forecast follows a period in which Crete’s storms have eased but saturated ground has kept flood risk elevated, and comes after Crete recorded some of the country’s lowest temperatures earlier in October.