Final answer:
The antonym of 'dismal' is 'sunny'.
Step-by-step explanation:
The antonym of 'dismal' is sunny. 'Dismal' means gloomy or depressing, while 'sunny' means bright and cheerful.
For example, in the sentence 'The weather went from dismal to sunny in a matter of hours,' the word 'dismal' is used to show a negative and melancholic weather condition whereas the word 'sunny' is used to represent a positive and pleasant weather condition.