  The prediction of solar activity is important for advanced technologies and
space activities. The peak sunspot number (SSN), which can represent the solar
activity, has declined continuously in the past four solar cycles (21$-$24),
and the Sun would experience a Dalton-like minimum, or even the Maunder-like
minimum, if the declining trend continues in the following several cycles, so
that the predictions of solar activity for cycles 25 and 26 are crucial. In Qin
& Wu, 2018, ApJ, we established an SSN prediction model denoted as
two-parameter modified logistic prediction (TMLP) model, which can predict the
variation of SSNs in a solar cycle if the start time of the cycle has been
determined. In this work, we obtain a new model denoted as TMLP-extension
(TMLP-E), which can predict the solar cycle nearly two cycles in advance, so
that the predictions of cycles 25 and 26 are made. It is found that the
predicted solar maximum, ascent time, and cycle length are 115.1, 4.84 yr, and
11.06 yr, respectively, for cycle 25, and 107.3, 4.80 yr, and 10.97 yr,
respectively, for cycle 26. The solar activities of cycles 25 and 26 are
predicted to be at the same level as that of cycle 24, but will not decrease
further. We therefore suggest that the cycles 24$-$26 are at a minimum of
Gleissberg cycle.
