Why do you use でははぃぃだそぅですよ after the weather forecast?

The usage of this "で" is: indicating the basis, basis and dependence. For example:

1 The personal clock is three o'clock/According to my watch, it is three o'clock.

2 meals/meals with pens.

It is correct to translate "according to the weather forecast" upstairs, but it is a bit like "in".