Idiomatic phrase: to be in for, it is to be expected.
Luvassa is the inessive singular form of lupa which means ”permission” or a ”license” or ”permit.” There is also a related verb, luvata, which means ”to promise,” ”to vow” or ”to bode” which has a similar meaning to the idiomatic phrase olla luvassa as in ”it bodes” to be . . .
If you have a better explanation of the origin of this idiomatic phrase, please leave it in the comments.
As is common in newspaper headlines, a form of the verb olla is omitted, but it is implied. If the verb were there, the phrase would likely be ”Luvassa on lämmin syksy,” and it would be translated idiomatically as ”We’re in for a warm autumn.” ”Luvassa on” is often seen in the news when talking about things (especially weather) which are expected or coming up.
”Uusi pitkän ajan ennuste” means ”A new long-term forecast.”