In essence, this paper is saying the weather/climate has become less extreme, with little to no change in maximum temperatures "and even some cooling" of maximum temperatures in some stations, and warming of minimum temperatures. Thus the temperature range between minimum and maximum temperatures has decreased, a less extreme, more benign climate.
According to the paper, the warming in minimum temperatures is regional, with the SE US showing "the least warming (even some cooling)," suggesting that other processes such as ocean and atmospheric oscillations are responsible, rather than a uniform warming from AGW.
Note these results are after the huge up-justments made to the US temperature data and urban heat island [UHI] artificial warming, which could account for all or most of the warming of minimum temperatures.
UPDATE: Graph from Verity Jones from the cross-post at WUWT showing cooling stations in blue/green in not only the SE US, but nationwide:
Journal of Climate 2014 ; e-View
Li and Robert Lund
Li and Robert Lund
This paper develops trend estimation techniques for monthly maximum and minimum temperature time series observed in the conterminous 48 United States over the last century. While most scientists concur that this region has warmed on aggregate, there is no a priori reason to believe that temporal trends in extremes and averages will exhibit the same patterns. Indeed, under minor regularity conditions, the sample partial sum and maximum of stationary time series are asymptotically independent (statistically). Previous authors have suggested that minimum temperatures are warming faster than maximum temperatures in the United States; such an aspect can be investigated via our methods. Here, statistical models with extreme value and changepoint features are used to estimate trends and their standard errors. A spatial smoothing is then done to extract general structure. The results show that monthly maximum temperatures are not often greatly changing — perhaps surprisingly, there are many stations that show some cooling. In contrast, the minimum temperatures show significant warming. Overall, the Southeastern United States shows the least warming (even some cooling), and the Western United States, Northern Midwest, and New England have experienced the most warming.