Good weather is coming during the week.
'Settimana' — set-ti-MA-na. Stress on the third syllable. 'In settimana' = during the week (this week).
Use to share positive weather news — especially when current weather is bad and improvement is forecast. Weather hope is socially valuable in Italy.
'In settimana' means 'during the week' or 'this week'. 'Arriva il bel tempo' uses 'arrivare' (to arrive) for the weather coming — weather moves and arrives like a guest. This is a forward-looking, optimistic phrase.
Da mercoledì migliora.
From Wednesday it gets better.
Specific day — shows you've checked the forecast carefully
Tornano le schiarite.
The bright spells are returning.
'Schiarite' (bright spells, clearings) — meteorological term used in everyday Italian
Presto torna il sole, vedrai.
The sun will be back soon, you'll see.
Reassuring and optimistic — 'vedrai' (you'll see) adds confident prediction
Italian weather reports on television give day-by-day forecasts up to a week ahead, accompanied by sun and cloud symbols. Viewers memorise the coming week's forecast and share it socially as if announcing community news.