The regex can be written in more simple way.

I thinkt it's better to use array then List, becuz that is written that every town has a number for every month. (there are 12 mounts always). Second note from me is that ya call parseTemp() 2 times in variance().

oh, ya're right.

I think it's better to put the chance to return null sooner... if ya have 2 the same abs(integers) in the table there is no reason to compute the rest of the function.

it's unreadable :(

recursion is not good if the size of figures will be enourmous and the difference between sides.