NOAA/NCEI U.S. Climate Division Data Plotting Page: Data Notes

1. 05/05/2018: Added PMDI,ZMDI, PHDI
2. 10/17/2014: Heating and Cooling Degrees Added.
3. 10/17/2014: Mean plots no longer default to white in middle.
4. 10/01/2014: Tmax and Tmin are available in the new version of the dataset and they have been added to this plotting page

Caveats

1. Stations go into and out of the record. See the NCEI webpage and ftp site for more information about the stations and about their QC process.
2. Data is subject to change at a later date (often 6 months later) though in practice, most values don't change.
3. PDSI values are calculated at NCEI for each division based on the temperature and precipitation. The PDSI is not linear so averaging different months is not the same thing as getting the PDSI from average temperature and precipitation.
4. Stations go into and out of the averages depending on many factors. NCEI has the stations that went into averages in their ftp site. See NCEI for more information on data QC.
5. HDD and CDD often will have "0" mean for certain regions and/or seasons. Ranks and percentiles may yield odd results if all or most of the values are 0. Please keep that in mind in interpreting those plots.