Why was the weather particularly sultry before the typhoon came?

Typhoon is a low-pressure system. The air flow in the center of low pressure is rising (see typhoon structure diagram). The updraft will flow around at high altitude and sink at the outer edge of the typhoon, so the area at the outer edge of the typhoon will be sultry because of downward flow. (So it will be sultry outside the typhoon, but it is not necessarily the typhoon. )