aestival
alternate
arctic
autumn
autumnal
beating
boreal
brumal
canicular
circling
cyclic
epochal
equinoctial
even
every other
hibernal
hiemal
intermittent
isochronal
measured
metronomic
midsummer
midwinter
oscillatory
out of season
periodic
periodical
pulsing
reciprocal
recurrent
recurring
rhythmic
rotary
serial
solstitial
spring
springlike
steady
summer
summerlike
summerly
summery
undulant
undulatory
vernal
wavelike
wheeling
winter
winterlike
wintery
worker
agricultural
annual
climatic
cyclical
daily
diurnal
economic
favorable
large-scale
physiological
short-term
statistical
unseasonal