Does the time difference between Chicago and São Paulo change during the year?

Yes. Because of daylight saving time the gap moves between −3h and −2h.

When is the best time to call São Paulo from Chicago?

Between 09:00 and 15:00 in Chicago, which is 11:00 to 17:00 in São Paulo.

Chicago is 2h behind São Paulo. This gap is not fixed: daylight saving time moves it between −3h and −2h during the year.

Chicago

United States

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São Paulo

Brazil

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A 9-to-5 day in each city overlaps for 6h. That is 09:00–15:00 in Chicago, which is 11:00–17:00 in São Paulo.

City	Time zone	UTC offset
Chicago · United States	America/Chicago	UTC−5
São Paulo · Brazil	America/Sao_Paulo	UTC−3

What is the time difference between Chicago and São Paulo?: Chicago is 2h behind São Paulo. This gap is not fixed: daylight saving time moves it between −3h and −2h during the year.
Does the time difference between Chicago and São Paulo change during the year?: Yes. Because of daylight saving time the gap moves between −3h and −2h.
When is the best time to call São Paulo from Chicago?: Between 09:00 and 15:00 in Chicago, which is 11:00 to 17:00 in São Paulo.