Airports serving beach destinations often gain several nonstop routes for a summer and lose all of them by autumn. The seasonality reflects how aircraft are allocated rather than how popular the coast is.
An aircraft is a mobile asset
An airline's fleet is the expensive part of its business, and each aircraft is expected to fly a set number of hours a day wherever that produces the most revenue. Aircraft are not attached to a region.
That mobility means a route only needs to beat the next best use of the same airplane for the months it operates. A shore market can clear that bar in July and fail it badly in February.
Airlines therefore build a seasonal schedule as a whole, shifting capacity toward beach markets in summer and toward warm-weather winter destinations later in the year.
Leisure coasts have almost no base traffic
Business travel produces steady weekday demand that is largely indifferent to weather. Most beach towns generate very little of it, so demand is composed almost entirely of vacationers.
Vacation demand collapses outside the season rather than tapering. A route can be full for ten weeks and carry a handful of passengers a day in the eleventh.
Small permanent populations also mean limited visiting-friends-and-relatives traffic, which is what keeps some other small airports viable through the winter.
The airport's own costs follow the same curve
Terminals sized for peak weekends are expensive to staff and heat for a handful of daily passengers. Screening, rescue and fire coverage, and ground handling all have to be present for even one flight.
Many small airports address this with contract handling and seasonal staffing, and some reduce staffed hours substantially in the off months. The facility exists year-round but is not fully manned year-round.
Weekend-heavy patterns follow from rental turnover
Coastal rental weeks commonly begin and end on a fixed changeover day, which concentrates arrivals and departures into a narrow window. Airlines schedule against that concentration.
The result is a beach airport that may see several jets on a Saturday and none on a Tuesday, which is unusual at airports serving mixed traffic.
It also means a midweek arrival can be both cheaper and easier, since the aircraft flying it is filling an otherwise idle rotation.
What this means for planning a coastal trip
A nonstop that existed last August is not evidence it will exist this August, and seasonal routes are frequently announced only a few months ahead. Checking the schedule for your actual dates matters more here than elsewhere.
Where the seasonal nonstop does not line up, the practical alternative is usually a larger airport within driving distance that keeps its schedule all year.