Greece faces heavy-rain forecast as Montenegro records sharp day-to-night temperature swings

Greece faces a forecast of heavy rain on 13–14 October, particularly around the Sporades islands, as a low-pressure system moves toward the Aegean Sea. Reports published on 12 October warn that some places could receive more than 100mm over 48 hours. The forecast matters for communities where intense rain could overwhelm streams or drainage.

The expected rain follows a separate spell of unusually wide day-to-night temperature swings in the Balkans. In Montenegro, warm days and cold nights occurred under high pressure and clear skies, according to the Guardian. The reports do not establish a common cause for the temperature swings and the system approaching Greece.

Where heavy rain is forecast in Greece

Greek news outlet Proto Thema reported a forecast by meteorologist George Tsatrafyllias for severe weather on Tuesday 13 and Wednesday 14 October. It identified Magnesia, the Sporades and northern and central Evia as areas where rainfall could locally exceed 100mm over 48 hours. Some scenarios put totals at 130–150mm. The report said the most intense conditions were expected from Tuesday afternoon into Wednesday morning.

A separate report by SkiathosVoice described an increased chance of rain and local thunderstorms in the Northern Sporades from 13 to 15 October, particularly on Skiathos, Skopelos and Alonnisos. Its forecast window extends a day beyond the period highlighted by Proto Thema.

SkiathosVoice described one scenario showing locally up to 150mm in a few hours over the sea between Skiathos, Skopelos and Alonnisos. The outlet cautioned that the amount was a scenario for the sea between the islands, not a confirmed total for the islands themselves. It said the intensity, duration and geographic distribution remained uncertain.

Why the forecast totals matter

The forecast amounts are large relative to average October rainfall cited by Proto Thema: about 65mm in Volos, 75mm in Skiathos and 60mm in Chalkida. Those monthly averages put the possible 48-hour totals in context. They do not show how much rain will fall in any one place during this system.

Proto Thema identified overflowing streams, local flooding and landslides as possible concerns where heavy rain persists. It said the risk depends on rainfall intensity and duration, as well as ground and drainage conditions. The timing of the heaviest rain, from Tuesday afternoon into Wednesday morning in Tsatrafyllias's forecast, is therefore relevant alongside the total amount.

SkiathosVoice reported recent stormwater drainage problems on Skiathos. It warned that intense rain falling over inhabited areas could cause local drainage and flooding problems, and recommended preparedness measures including clearing drains. Whether the heaviest rain falls over inhabited areas remains an open part of the forecast.

What happened to temperatures in Montenegro

The Greek forecast comes after unusually large differences between daytime highs and overnight lows across the Balkans during the previous week, according to the Guardian. It attributed the pattern to high pressure bringing prolonged daytime sunshine, followed by clear nights that allowed heat to escape rapidly without cloud cover slowing the cooling.

In Kosanica, Montenegro, the difference between daytime and overnight temperatures reached 30C on 4 and 5 October, the Guardian reported. That was more than twice the usual October range there. The report gave average October maximum and minimum temperatures for Kosanica as 15C and 4C respectively, illustrating how unusual those two days were.

The Guardian also forecast showers for parts of Crete toward the end of the week. It reported that severe flooding on the island a week earlier had swept cars and trees into the sea. That damage preceded the approaching weather system and illustrates why new heavy-rain forecasts may be watched closely there.

What remains uncertain about the rain

For residents of the forecast areas, the key questions are where the heaviest rain will fall and how long it will last. SkiathosVoice said later forecast runs would show whether its heavy-rain signal persisted or weakened. Proto Thema's forecast identifies areas at risk on 13–14 October, while the Guardian expects the system to move into the Aegean by midweek.