As noted here, there is predictable month-month variation associated with choice of anomaly base period. That was partly responsible for the discrepancy between a May rise in the index, and a flat GISS. To try to counter this variation, I have added a section of the table below the monthly indices which tries to put the index on the same anomaly base as GISS or NOAA. It can't do this directly (lacks good data), but can work out that component of the change based on other indices during 1994-2013. IOW, it's the corrected prior estimate for those indices. That estimate is that GISS should be about the same as May (0.72°C), while NOAA should be about the same as April. However, NOAA has been consistently exceeding expectations lately.
Update. Troposphere data: RSS is up from 0.31 to 0.391°C; UAH v6 is up from 0.27 to 0.31.