Breakdown of Ontem também estava nublado, e mesmo assim nós fomos caminhar.
Questions & Answers about Ontem também estava nublado, e mesmo assim nós fomos caminhar.
Because estava uses the imperfect past, which is very common for background description in the past.
In this sentence, the weather is being described as the situation in the background:
- Ontem também estava nublado = Yesterday it was cloudy too
That is different from a completed event. Weather, time, atmosphere, and ongoing conditions often use the imperfect:
- Estava frio. = It was cold.
- Estava chovendo. = It was raining.
- Era tarde. = It was late.
Using foi would sound much less natural here, because foi usually presents something as a completed, bounded fact rather than a background condition.
Também means also / too.
So:
- Ontem também estava nublado = Yesterday it was cloudy too / also cloudy yesterday
It connects this sentence to some previous idea, such as:
- Today is cloudy.
- Ontem também estava nublado.
In Portuguese, também is flexible in position, but here it naturally comes after ontem.