From June to December, the average rainfall changes as follows:
- In June, the average rainfall is 0.2 inches.
- In July, it slightly increases to 0.45 inches.
- In August, it continues to increase to 0.55 inches.
- In September, it increases again to 0.7 inches.
- In October, there is a notable increase to 1.6 inches.
- In November, it rises further to 2.4 inches.
- Finally, in December, it reaches 3.2 inches.
Based on this analysis, from June to December, the average rainfall consistently increases.
Therefore, the appropriate response is:
the average rainfall increases.