Answer:
Use Two sided t-test
Explanation:
Note that, there are other tools to test for significant difference such as simple regression or multiple regression but when comparing the results of two groups in terms of which is higher or lower, then a two sided t-test would be best appropriate.
Since we want to know if there is a significant difference between the number of tornadoes in August and the number of tornadoes in October on average we use the two sided t-test because a Two sided t-test can show the possibility of positive or negative differences.