From NOAA’s Global Climate Report – April 2021:
The April 2021 global surface temperature was 0.79°C (1.42°F) above the 20th century average of 13.7°C (56.7°F). This was the smallest value for April since 2013 and was the ninth warmest April in the 142-year record. April 2021 marked the 45th consecutive April and the 436th consecutive month with temperatures, at least nominally, above the 20th-century average. December 1984 was the last time a monthly temperature was below average.
Time series data is available near the top of the page.