adjective.
Typical of or suitable for the season or the time of year.
adjective.
Occurring or performed at a suitable or proper time; opportune.
The Century Dictionary and Cyclopedia
Suitable as to time or season; opportune; occurring, happening, or done in due season or proper time for the purpose; in keeping with the season or with the circumstances: as, a seasonable supply of rain.
the GNU version of the Collaborative International Dictionary of English
adjective.
Occurring in good time, in due season, or in proper time for the purpose; suitable to the season; opportune; timely.