Which Year Was Most Extreme?
By Paul Homewood
According to NCDC, 2012 was the second most extreme year, weather wise, for the CONUS, the most extreme year being 1998. As previously discussed, NCDC use six indicators to build up their “US Climate Extremes Index”:-
- Daytime temperatures.
- Night time temperatures.
- PDSI drought index.
- Extreme rainfall events.
- Unusually dry or wet spells.
- Landfalling tropical storms/hurricanes.
2012 came out first and second most extreme on the top 2 categories, respectively, and seventh on the PDSI index. On the other three indices, the year was well below average. In other words, the “extreme label” arose purely because temperatures were much higher than normal, (normal being the 1910-2012 average). Indeed, if the temperature indices had not been duplicated, the year would have dropped to 5th place.
However, a comparison with 1936 questions whether the temperature index is even measuring “extreme weather” in any meaningful way. From NCDC, the CONUS mean temperatures for each season are shown below for the two years, along with the Meteorological Year (Dec-Nov).
The following facts are worth noting:-
- The winter in 1936 was the 2nd coldest on record. Only the winter of 1979 was colder.
- The summer of 1936 was the hottest on record.
- Annually, 2012 was warmest, whereas 1936 was ranked 72.
So, a very hot summer and very cold winter in 1936 cancelled each other out, to something about average! It is no surprise then that the “US Climate Extremes Index” for maximum temperature shows 1936 as one of the least extreme on record, while 2012 is top.
So, which year really was the more extreme?