Learn Croatian: Današnja prognoza je vrlo promjenjiva. - Today's forecast is very changeable.

To turn a time-related adverb like danas into an adjective, we use the suffix -šnji (or sometimes -nji). With danas, the final s blends into the š of the suffix, giving us the base adjective današnji. Here, it takes the feminine ending -a to agree with prognoza. Other common examples following this pattern are sutrašnji (tomorrow's) and jučerašnji (yesterday's).

Is it possible to say prognoza od danas instead of using the adjective današnja?

You can, and people will understand you perfectly. However, using derived temporal adjectives like današnja is the much more natural and standard way to express this in Croatian. Mastering these adjectives instead of relying on od (from) phrases will make you sound much more fluent at the B2 level.

What does the suffix in promjenjiva tell us about the word?

The base suffix is -jiv (often seen as -ljiv), which builds adjectives meaning 'capable of' or 'prone to', similar to the English suffix '-able'. When attached to the root of promjena (change), it creates promjenjiv (changeable). It takes the -a ending here to agree with the feminine noun prognoza.