Graph pattern recognion in Java

I'm not sure if the title is accurate based on the problem.

I have a list of numbers that can be represented as a graph, in this case I am dealing with temperature readings. There are certain sections of this data that I want to look at. Specifically I want to find the indices where the section starts and ends.

This is easy enough with the human eye, but I want this done automatically in Java.

Here are some examples of the kind of data im looking at. The green line indicates the beginning of a section and the red line indicates the end of a section: 1 4

(I don't have the reputation to add more than these)

I tried a very rudimentary way which worked for example 1 but does not work with any other. BTW example 1 is in Celsius, the others Fahrenheit