@fanfan , not sure if that may help you, but in my case I discovered that even in sleep mode the BME280 still drawing current (up to 1mA). The only solution I found was to bring down the SCL and SDA pins before entering in the sleep mode.
Something like this:
digitalWrite( A4 , LOW ); digitalWrite( A5 , LOW ); sleep( 60000 ); wait(200); weather_sensor.begin(); wait(200);
Not sure if this is best way but it worked for me...