April global surface TempLS down 0.097°C from March.

The TempLS mesh anomaly (1961-90 base) was 0.872deg;C in April vs 0.969°C in March. As with the very similar drop (0.086) in the NCEP/NCAR reanalysis base index, that still makes it a very warm April, the second warmest in the record. It was the warmest month since March 2017.

GHCN V4 results were a little later this month. I've noticed a reversion to the V3 custom of reporting by country; earlier it seemed that most countries were represented at an earlier stage. I'm a bit late reporting, too, because I found that the preliminry results changed from day to day. But I think all the main countries are in now.

This time the very warm Arctic region was in NE Siberia, with a rather cool spot NW of Canada. Europe was warm, and China, especially W.  Africa was warm, the Middle East rather cool.
Here is the temperature map, using a spherical harmonics approximation to the mesh results.



And here is the map of stations reporting:

This post is part of a series that has now run since 2011. The TempLS mesh data is reported here, and the recent history of monthly readings is here. Unadjusted GHCN is normally used, but if you click the TempLS button there, it will show data with adjusted, and also with different integration methods. There is an interactive graph using 1981-2010 base period here which you can use to show different periods, or compare with other indices. There is a general guide to TempLS here.

The reporting cycle starts with a report of the daily reanalysis index on about the 4th of the month. The next post is this, the TempLS report, usually about the 8th. Then when the GISS result comes out, usually about the 15th, I discuss it and compare with TempLS. The TempLS graph uses a spherical harmonics to the TempLS mesh residuals; the residuals are displayed more directly using a triangular grid in a better resolved WebGL plot here.

A list of earlier monthly reports of each series in date order is here:

1. NCEP/NCAR Reanalysis report
2. TempLS report
3. GISS report and comparison with TempLS