Questions & Answers about Пасмурный день не мешает мне гулять в парке.
Because it describes день (day), and день is a masculine noun.
In Russian, adjectives must agree with the noun they describe in:
- gender
- number
- case
Here:
- день = masculine, singular, nominative
- so the adjective is пасмурный
Compare:
- пасмурный день = a cloudy day
- пасмурная погода = cloudy weather
- пасмурное утро = a cloudy morning
День is in the nominative singular because it is the subject of the sentence — the thing doing the action.
The sentence literally works like:
- Пасмурный день = the cloudy day
- не мешает = does not hinder / does not prevent
- мне = me
- гулять в парке = from walking in the park
So день is the thing that does not interfere, which makes it the subject.