That'd be a record-high for the month, smashing last year's record of +0.77°C, and the 6th-warmest of any month since GISS's records began in 1880.
It would also bring the warming in 10 years up to +0.08°C, in 15 years to +0.14°C, and in 30 years to +0.49°C. Seems the Pause is itself pausing.
My estimate last month for April (0.66°C) was
so don't take my number to the bank.
Nota bene: Turns out GISS corrected their numbers a few days after they first came out (May 15th), which I didn't catch, which explains why I had some incorrect some numbers above. Their new numbers don't change my estimate for May.