Ottawa (Station 4333) Days of Hot and Cold

To show even more that the summers are not getting hotter, this graph shows the number of days per year that are 30C or more.  Considered heatwaves.

On the other side of the spectrum, the number of days below -25C.  Notice the drop off, that is we have experiencing fewer super cold days in the winter today that we were in the 1930s.

What is interesting is that both graphs appear to have some kind of cycle, of some 20 years for the hot days, and some 15 or so years for a cold cycle.

What appears to happen is after a single year of not many hot days, the following years increase in the number of hot days until a maximum is reached for one year, then drops back down again.  Same for the cold days.

If this is true, we can expect the number of hot days above 30 to increase for the next few years.  Just some kind of pulse of the climate, nothing to do with human emissions of CO2.

Last graph is the number of days below freezing.  Clearly the number of days each year is in a frozen state is dropping.  Not so good for private backyard rinks.