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

Yes. Because of daylight saving time the gap moves between +4h and +5h.

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

Between 13:00 and 17:00 in São Paulo, which is 09:00 to 13:00 in Vancouver.

São Paulo is 4h ahead of Vancouver. This gap is not fixed: daylight saving time moves it between +4h and +5h during the year.

São Paulo

Brazil

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Vancouver

Canada

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A 9-to-5 day in each city overlaps for 4h. That is 13:00–17:00 in São Paulo, which is 09:00–13:00 in Vancouver.

City	Time zone	UTC offset
São Paulo · Brazil	America/Sao_Paulo	UTC−3
Vancouver · Canada	America/Vancouver	UTC−7

What is the time difference between São Paulo and Vancouver?: São Paulo is 4h ahead of Vancouver. This gap is not fixed: daylight saving time moves it between +4h and +5h during the year.
Does the time difference between São Paulo and Vancouver change during the year?: Yes. Because of daylight saving time the gap moves between +4h and +5h.
When is the best time to call Vancouver from São Paulo?: Between 13:00 and 17:00 in São Paulo, which is 09:00 to 13:00 in Vancouver.