I can say that it is as you say. I don’t know this app, but ours takes the values of the forecasts which are defined in timespans. The backend loops over that and matches it to texts to construct a blurb like that.

It could simply be that the meteorologist defined a seperate period as more intense or is associated with a weather warning. And the simple automation of this app doesn’t check for continuity.

To be fair, I am unsure if ours does this as well. I don’t work directly on the app. I am an infrastructure guy. I do know it is checked by a human meteorologist before updating or publishing.