The twister struck Friday, The Portugal News reported. Meteorologists said it began at sea and gained strength as it moved across the Atlantic Ocean to make landfall in the Algarve resort area.
Almost 5,000 people lost electrical power, officials said. All but 600 had the lights back on by Friday night.
A nursing home in Algoz was evacuated. In Lagoa, Deputy Mayor Rui Correa said the winds tore the facades off some buildings and damaged 70 to 80 apartments.
At least 13 people were injured, three of them seriously.
The weather remained threatening Saturday with rain, thunder and high winds, but no tornadoes materialized.