JAXA EXTENT DATA - 6,598,767 km2(April 24, 2018)
Extent gain has returned to below average, and well below that of 2017. As a result, 2018 is now just 185,000 km2 above 2017 compared with 1,300,000 in late March.
On average, extent gain is 32% done, and is an impressive 760,000 km2 (15%) less than the average to date. If history is a guide, 2018 is heading for a record low maximum of around 17.4 million km2. 8 out of 10 of the last 10 years agree. Even if remaining extent gain turns out at the maximum of the last 10 years, the 2018 maximum would be 18.4 million km2, the third lowest in the satellite record.