Balkan temperatures swing sharply as heavy rain heads for Greece

Last week the Balkans recorded unusually large gaps between daytime highs and overnight lows, a measure meteorologists call the diurnal range. Forecasts now point to heavy rain and strong winds in Greece this week, while an intense hurricane approaches the Pacific coast of Mexico.

Large swings in the Balkans

An area of high pressure sat over the region. By day it brought prolonged sunshine, and at night clear skies let heat escape rapidly into the atmosphere because there was no cloud cover to slow the cooling.

In Kosanica, Montenegro, October's average maximum temperature is 15C and the average minimum is 4C. On 4 and 5 October, however, the difference between the daytime high and the overnight low reached 30C, more than double the October average.

Rain for Greece

Over the coming week, high pressure will build across northern and western Europe and push a low-pressure system south towards the Mediterranean. The system will deepen as it crosses the Adriatic and Ionian seas, then move east into the Aegean Sea by the middle of the week.

Heavy rain and strong winds are expected across Greece as a result. Forecast models suggest widespread rainfall of 50–150mm, with the highest totals around the island of Skiathos. Towards the end of the week the system will continue east and bring showers to parts of Crete, which suffered severe flooding a week earlier. Those storms swept some cars and trees into the sea.

Hurricane Simon off Mexico

Meanwhile, Hurricane Simon, a category 4 storm, is moving close to Mexico's Pacific coast near the state of Jalisco. It is the latest of 21 named storms in the Pacific this season, 11 of which have reached hurricane strength.

At the time of writing, Simon has a central pressure of 933mb and maximum sustained winds of nearly 150mph (241km/h). The hurricane is expected to weaken rapidly if its core moves onshore, cutting it off from the warm ocean waters that fuel it.

Heavy rainfall is affecting south-western Mexico, where totals could reach 300–400mm across a wide area and 400–500mm in the wettest locations.