Learn Swedish: Vädret var fantastiskt. - The weather was fantastic.

var is the past tense of att vara (to be), meaning "was" or "were". In Swedish, verbs do not change based on who or what the subject is. Whether it is "I was" (jag var), "they were" (de var), or "the weather was" (vädret var), the verb stays exactly the same.

How do we know vädret means "the weather" and not just "weather"?

In Swedish, "the" is usually attached to the end of the noun instead of being a separate word. The base word for "weather" is väder (an ett-word). To say "the weather", we add -et to the end, making it vädret. Notice that the second 'e' in väder is dropped to make it easier to pronounce!

Why does fantastiskt end with a -t?

Adjectives must match the noun they describe. Because vädret (the weather) is an ett-word, the adjective gets a -t added to the end. If we were describing an en-word, like a day (en dag), it would just be fantastisk.

If I wanted to ask "Was the weather fantastic?", how would this sentence change?

You would simply swap the subject (vädret) and the verb (var). The question becomes: Var vädret fantastiskt? Putting the verb first is the standard way to turn a statement into a yes/no question in Swedish.