No, summer isn't over yet, but we'll have to wait a few more days to feel the temperatures rising.

According to the Luso Meteo weather service, September is expected to be very hot and dry, with some cooler or rainy days expected, as was the case this Sunday. However, these meteorologists' forecast points to "several days of above-normal temperatures, and even the potential for a heat wave."
It is therefore expected that the weather will warm up from the 12th onwards, “with the approach of the anticyclone, and the end of the blockage in higher latitudes.
After a somewhat cool and unstable start to September, temperatures are expected to rise significantly, "with days when thermometers will hover around 40°C in traditionally hotter areas, something that could continue until at least September 19th to 21st, with dry weather."
Visao