Portugal's prolonged drought is getting worse despite the end of summer, with the entire country now officially classified as suffering from either "severe" or "extreme" drought conditions.

The Portuguese Weather Institute says in its monthly report that it is the first time on record that a severe drought extended into October, when rainfall usually brings some relief.

The institute, a government agency, said in a report Thursday that last month was the hottest October in 87 years and the driest in 20 years.

Almost half the country's 60 major reservoirs are currently below 40 percent of their capacity.

The parched conditions have aided the spread of deadly wildfires this year, with woodland blazes killing more than 100 people.