GISS has reported an anomaly average of 0.71°C for May 2015, the same as for April. This is in agreement with TempLS mesh, but in contrast to the rise in the troposphere measures RSS and UAH.
I was surprised by the TempLS result, since the NCEP/NCAR index had indicated a much warmer result. HADSST3 also rose in May. But the GISS result essentially confirms it. It coincides with the new version 3.3 of GHCN, which would have influenced both indices. But that change made little difference to previous months. I am planning to post a study of the anomaly differences between April and May.
TempLS Grid also rose by about 0.05°C, so I think May rises in HADCRUT and NOAA are likely.
Below the fold is the customary comparison between GISS and TempLS.
Here is the GISS map for May:
And here is the corresponding TempLS map, using spherical harmonics: