Still, you can see signs: the maximum temperature until 1990 or so seems to be around 35 degrees, since then there are several peaks above that value and in 2016 (?) it looks to be 38-39. It's certainly less visible on the peaks in the low, because maybe the absolute lowest scores appear to be in the 1990-2000 decade, but then again, all years in the 2010-2020 decade seem to be slightly higher than the minimum temperature in any other decade.
That said, there is massive downscaling involved in such scale, so I wouldn't be too surprised if some details were just skipped and not visible. I wouldn't trust this interpretation much - if a visualization it needs to be, I'd rather plot a moving average with a window of 6 months at least (or even 1 year to entirely rule seasonalities out), and see if that one has an upward trend or not (I bet it does).
[EDIT] I now see the post below with the year averages since 1979. It does indeed seem that 1995-1997 were abnormally cold years, and also that 2010-2020 is the warmest decade since then (and likely since quite a bit longer). So the outliers analysis here above seem to stand :-)