Digitized images of full disk CaK spectroheliograms from two solar observatories were used to study cycle variation of ephemeral regions ( ERs ) over ten solar cycles 14-23 .
We calculate monthly averaged unsigned latitude of ERs and compare it with annual sunspot number .
We find that average latitude of ERs can be used as a predictor for strength of solar cycle .
For a short-term prediction ( dT \sim 1-2 years ) , maximum latitude of ephemeral regions ( in current cycle ) defines the amplitude of that cycle ( higher is the latitude of ERs , larger are the amplitudes of sunspot cycle ) .
For a long-term prediction ( dT \sim 1.5 solar cycles ) , latitude of ERs at declining phase of n ^ { th } cycle determines the amplitude of ( n+2 ) ^ { th } sunspot cycle ( lower is the latitude of ERs , stronger is the cycle ) .
Using this latter dependency , we forecast the amplitude of sunspot cycle 24 at W=92 \pm 13 ( in units of annual sunspot number ) .