Learn Portuguese (Portugal): Fico em casa, pois está a chover. - I am staying home, because it is raining.

In Portuguese, the simple present tense (fico) is often used for actions happening right now or decisions made for the immediate future. While you could technically say estou a ficar, simply saying fico is much more natural and common for "I am staying" in this context.

Why is it em casa instead of na casa?

Em casa is a fixed phrase that translates directly to "at home". If you use na casa (which combines em + the feminine article a), it sounds like you are saying "in the house", referring to a specific physical building rather than your own personal home.

I normally use porque for "because". Can I use it here instead of pois?

Yes, you can absolutely use porque here! In this sentence, pois works exactly like porque as a word meaning "because" or "since". Using pois is a great way to add variety to your vocabulary, though it can sound slightly more formal in speech.

The sentence ends with está a chover. Is that the standard way to say it is currently raining?