In what year did solar cycle 24 reach its peak?

Solar cycle 24 reached its peak in 2014. The cycle's smoothed sunspot-number maximum occurred in April 2014, although the cycle had a double-peaked maximum: an earlier activity peak appeared in 2011, followed by the stronger second peak in early 2014.

Solar cycle 24 began around December 2008, after an unusually deep solar minimum, and ended in December 2019. Its maximum was relatively weak compared with many preceding cycles, with the smoothed sunspot number reaching about 81.8 in one commonly used series. Other sunspot-number revisions and counting methods give somewhat different numerical values, but they retain 2014 as the peak year.

The year can be confused with 2011 because that was the first peak of the cycle. Solar activity does not rise and fall in a perfectly symmetrical pattern, and the official maximum is determined from smoothed sunspot data rather than from a single spectacular flare. The cycle was the 24th recorded since systematic observations began in 1755.