Rainy season starts in São Paulo
Normally the wet season in Southeast Brazil starts in November, but in November this year the average quantity of precipitation was below normal.
Now the last three days it has rained all afternoons. That is normal.
The day start with a bright morning, nice temperatures, but after noon humidity and temperature start to build up, and heavy Cumulus Nimbus clouds arrive, and overcast the sky.
Between 15:00 and 18:00 hours the tropical showers start to fall, and such a shower takes 10 to 20 minutes to loose all of its water, which results in 20 to 30 mm of rain.
Then the sky opens again, and show the last daylight, until the next clouds arrive.