The Baton Rouge Zoo experienced its lowest attendance in at least 20 years during the summer season this year, and zoo officials are blaming sizzling hot temperatures for keeping the crowds down.

Zoo Director Phil Frost said the zoo drew 37,744 visitors during June, July and August — 11,006 fewer than last year and the lowest number since at least 1991, based on attendance records.

“For the first five months of the year, we were doing very well, then we got hit with that brutal heat,” Frost said.

The summer saw temperatures frequently soar into the upper 90s, with several days reaching triple digits.

Admission fees are an important source of revenue for the zoo, and officials say they are hoping attendance continues to pick up with the arrival of cooler weather.

Many zoos in the Southeast tend to attract their biggest crowds in spring and fall, when temperatures are milder, Frost said.

“We get a lot of people when spring hits and then traditionally the numbers drop off until mid-September,” he said. “Summer is always a difficult time for our zoo.”

Added Bob Rainer, president of Friends of the Zoo, “We’re just the victims of where we live.”

Frost said attendance picked up in September, and the zoo is looking for strong attendance in October for events such as Boo at the Zoo.

The popular annual event, held over two weekends in October, is tied to the Halloween season. Area businesses and organizations set up treat stations where candy and treats are handed out to children in Halloween costumes.

Boo at the Zoo is being held this year on Oct. 15-16 and Oct. 22-23, Frost said.

“Last year, we had 31,000 visitors during those four days,” Frost said. “They passed out 900,000 pieces of candy. That’s a lot of candy.”

Attendance at the zoo through August totaled 161,948, which is 12,395 less than attendance for the same eight months in 2010, zoo officials said.

Despite the lower number of visitors this year, the zoo’s earned revenue through August actually was up slightly compared to the same period last year.

The zoo took in $1,430,785 for the first eight months of this year compared to $1,422,383 last year, according to figures provided by zoo officials.

Frost said revenues were up because there were more corporate picnics, concession and gift shop sales were strong and the zoo had a nearly sold-out summer camp program for youths.

About half of the zoo’s $3,760,00 annual operating revenue comes from admission fees, concession sales and fees collected from summer camps and other special programs, Frost said. The rest comes from a dedicated tax that supports BREC programs, he said.

Zoo officials are preparing a proposed budget for next year that envisions raising admission fees by $1.25 per person in January, something that requires approval of the board that oversees BREC.

The admission fee for adults visiting the zoo is $7 each, while the charge for children ages 2-12 is $4 each. If approved by BREC, the fees would be raised to $8.25 for adults and $5.25 for children.

Frost has said the zoo generally raises admission fees every other year to try to keep up with increased operating expenses, such as the cost of food for the animals, fuel and utilities.