This is the 186th most frequent Czech word.
loňského
"Loňského" means "last year’s" or "of last year" in English.
In this sentence, "loňského" is used to describe the hero (also in the genitive case) in relation to the previous year.
Připomínejme si loňského hrdinu.
Let's remember last year's hero.
"Loňského" is utilized here to modify "deště" (rainfall), specifying rainfall related to the previous year.
Loňského deště bylo více než obvykle.
Last year's rainfall was more than usual.
"Loňského" is used here as a genitive singular form agreeing with "vítěze," describing possession or association of the winner with last year.