Gathering at Barton Springs Pool for a full moon howl is practically a rite of passage in Austin — but partaking in the city’s “weird” nighttime tradition comes at a cost.

Though the pool requires a small entry fee between 8 a.m. and 9 p.m., admission is typically free between 5 and 8 a.m. and during its final hour of operation, from 9 to 10 p.m.

The high volume of patrons during the full moon howl event each month requires the city to charge for entry after 9 p.m. on those days, just once per month.

The entry fee may have taken some people by surprise at the most recent howl Wednesday night, but it’s been a city policy since July 19, 2016, according to a spokesperson for Austin Parks and Recreation.

“Back then, as the howl at the moon nights gained in popularity, at the time we were working with public safety and the Austin Police Department to make sure the festive and fun experience stayed that way,” the spokesperson said.

He said the policy has remained in place ever since and is necessary to ensure the safety of swimmers and other attendees.

Children, ages 1 to 11: $2 (Austin residents), $4 (non-residents)

Teens, ages 12 to 17: $3 (residents), $5 (non-residents)

Adults, ages 18 to 62: $5 (residents), $9 (non-residents)

Seniors, ages 62 and older: $2 (residents), $5 (non-residents)

Entry for military veterans and infants is always free.

Tickets can be purchased with cash at the pool entrance, online via the ATX Swims app, or at kiosks outside both pool entrances. The kiosks accept credit and debit card purchases.

One Reddit user with the username u/bassplayinben said the rule makes sense based on their observations at June’s howl event.

Other users, including u/Good_Split_3749, u/FitPie46 and u/Hour-Ranger-5076, concurred.

Others, like u/digitalliquid and u/Expensive-Cod5238, felt disappointed that howl nights won’t allow free entry.