Seasonable describes something that is well-timed or opportune, often because it suits the season, while seasonal describes something that happens only at a particular time of year. Fresh strawberries in June are seasonal; a seasonable spell of warm weather in June is simply weather that fits the time of year.
The core difference
Seasonable is about timeliness or suitability; seasonal is about recurring at a fixed time of year.
- seasonable — opportune or suitable for the time of year: We had seasonable weather for the wedding, warm and dry as expected in July.
- seasonal — happening only at a certain time of year: The shop takes on seasonal staff over the Christmas period.
How to tell them apart
A useful trick: seasonable is close in meaning to "reasonable" — both are about something being fitting or appropriate, in this case appropriate to the time of year. Seasonal, by contrast, simply marks the calendar: a seasonal job, a seasonal fruit, a seasonal illness, all recur or exist only at a set point in the year.
The mix-up shows up most often in weather reports and retail copy, where writers reach for "seasonal weather" when they mean weather that fits the season — that is "seasonable weather". A seasonal event, on the other hand, is simply one tied to a particular season, regardless of whether conditions are typical for it.
