The Italian island Sardinia recorded, according to ISTAT data for 2026, up to 53 consecutive days without rain, the highest figure in the whole of Italy. Sicily follows with 41 days. From 1 January to 15 September 2026, Italy also recorded 75 days with heatwave conditions, surpassing the previous record of 59 days set in 2003.
Heatwave duration index 2026: highest level since 1991
According to the ISTAT annual report , the duration index measures the number of days with heatwave conditions within this observation window. In 2026, it rose 38 days above the 2025 comparison figure, marking the highest level since records began in 1991. On the two Italian islands, the average dry period had remained considerably lower in previous years: 23 days without rain in 2024 and 18 days in 2025. At 53 days, Sardinia's 2026 figure is more than two and a half times the two-year average for both islands. Italy had already been gripped by the summer heatwaves of 2026 in several waves; in early August, 25 of 27 monitored cities were on the highest warning level, bollino rosso.
Reservoirs at 61 per cent, critical sub-systems below 25
According to L'Unione Sarda , Sardinia's reservoirs held approximately 1.13 billion cubic metres of water as of 30 September 2026, equivalent to 61.08 per cent of approved capacity. Compared with August 2026 (66.55 per cent), the level fell by just over five percentage points; the regional indicator of 0.46 triggers a pre-alert . Three sub-systems are at particularly low levels: Posada at 9.43 per cent, Cedrino at 17.68 per cent, and Alto Cixerri at 24.80 per cent. Ogliastra also falls into this range at 38.17 per cent. In the north-west, the level stands at 47.61 per cent, placing it in the alert zone. In year-on-year comparison, the overall situation nevertheless remains considerably better than in 2025, when the fill level at the end of September stood at 38.76 per cent and the total volume amounted to only 716 million cubic metres.
High pressure persists, no improvement expected before month's end
According to Meteo.it , high pressure over Italy will persist until the end of the month, with little to no notable rainfall in the two southern island regions. Maximum temperatures on Sardinia and Sicily will reach 23 to 24 degrees; in the cold early morning hours, fogis forming across the Centro-Nord. The freezing level above the Alps will temporarily rise to 4,000 metres on Tuesday. Following the departure of the weather system Boelo towards Greece, the next Atlantic front is not expected to approach until early November at the earliest; thereafter, easterly flows will take hold, bringing temperatures back down. Current warnings for individual regions are updated on a continuous basis.
Long-term trend: Carbonia bottom of the climate ranking
The particular vulnerability of Sardinia and Sicily to drought is also reflected in the Indice del clima 2026 published by the newspaper Il Sole 24 Ore: the town of Carbonia in the south of Sardinia occupies last place in the ranking of 108 Italian provincial capitals. The methodology draws on 15 climate indicators covering the period 2015 to 2025, as well as data from 3bmeteo. Within Sardinia, Cagliari reaches 25th place with 727 out of 1,000 points, followed by Nuoro in 42nd place (659), Sassari in 64th (564), and Olbia in 74th (527). The province of Sud Sardegna sits in 105th place with 57 points.
As early as December 2025, Copernicus satellite images documented a volume loss of 162 million cubic metres at the central Sardinian lake Omodeo compared with 2023. Three Sentinel-2 images taken on 19 December 2023, 16 December 2024, and 11 December 2025 chart the progression: the volume fell from 349 million cubic metres (83.3 per cent) to 187 million cubic metres within two years, equivalent to less than 45 per cent of capacity. The Omodeo reservoir on the Tirso is the largest artificial water storage on the island; earlier periods of low water had exposed submerged structures on the lake bed.
