Since yesterday Sicily and most of Southern Italy have been experiencing very high temperatures due to hot air coming straight from the Sahara desert. This is the first heatwave of the season in most of the central Mediterranean.
Yesterday Palermo observed 39.4°C, breaking the all time record of May (+38,6°C) reached in 1994. Today, the weather conditions will be similar, with very high temperatures across the island (and most of the central/southern Italian peninsula) with risk of other breaking records.
Indeed, this morning, due to the combination between hot air advection and descending wind from the hills surrounding Palermo, temperatures in some areas have already reached 38/40°C in the W part of the city (thus breaking yesterday’s record).
In Figure1 we can see that the highest temperatures today are observed in the area of Palermo and Messina (E Sicily), whilst elsewhere temperatures are not too high (between 25/30°C).
The very high temperatures observed in these areas are mainly caused by the descending wind from the hills/mountains crossing E-W the Island, which are causing a foehn effect along the N coast. Indeed, the wind is causing a drop in the relative humidity (close or below 20% in some areas) which enhances the heating effect on the downwind side. In fact in these areas the wind is quite sustained (30/45km/h), whilst in the other sides of the island winds are weaker or come from the relatively cold sea, thus reducing the increase in temperature.
In summary, it’s a record heatwave for the island, but with still significant temperature differences within the same region.