Updated

Brazil's biggest city is experiencing one of its driest spells in years after more than a month with almost no rain.

Neide Oliveira of the National Meteorological Institute says in the month through Thursday just one-hundredth of an inch (0.3 millimeters) of rain has fallen on Sao Paulo. The average for this time of year is 1.5 inches (38 millimeters).

Oliveira says rain isn't expected for at least another week because a mass of hot and dry air is blocking cold fronts that normally bring rain from the ocean.

The city's humidity index plunged to 10 percent this week, the lowest in three years.

Officials are urging people to drink extra water and take special care while exercising. Hospitals say they've seen a spike in patients complaining of respiratory ailments.