The graph shows time in days from 0 to 900 and mean squared error up to about 10 degree celsius squared. Error increases from near 0 to about 9.5 by around 350 to 400 days, then decreases sharply near 500 days to about 5, rises again, drops near 580 days to about 4, and stabilises between 6 and 7.5 with small fluctuations towards 900 days.
Mean squared error between the real and the GraphSAGE predicted temperature for every time step