今晚一定是好天。

The weather will be good tonight for sure.

Source: Tatoeba

Sentence Composition

1 今晚 jīnwǎn tonight
2 一定 yīdìng
  1. surely
  2. certainly
  3. necessarily
  4. fixed
  5. a certain (extent etc)
  6. given
  7. particular
  8. must
=3 是 shì
  1. to be (followed by substantives only)
  2. correct; right; true
  3. (respectful acknowledgement of a command) very well
  4. (adverb for emphatic assertion)
=3 是 shì variant of 是 shì
4 好天 hǎotiān fine day; day of lovely weather