Using NOAA data at 61-90, 71-00, 81-10, and 91-20 norms for the south central US for the avg anomaly (in K) for Jan-Apr.
() is the difference from previous norm.
61-90: 0.221
71-00: -0.091 (0.312)
81-10: -0.374 (0.283)
91-20: -0.535 (0.161) (0.756 from 61-90)
Maps above are in F, so can't compare these with those necessarily, as F uses smaller units compared to K/C units (which are the same size).
Have to use lat/long here, but basically its CO, KS, OK, NM, and TX. I already have data downloaded (1981-2010 base) for 7 sections of the US from a while ago, so I plugged in the coordinates I have for this section. When using lat/long, the area is bigger in the south, than the north areas because of the arc of the Earth. Unfortunately, I do pick up some of MX and CA in those sections, but it's all good.
https://psl.noaa.gov/cgi-bin/data/testdap/timeseries.pl
Hope this helps.