The climate aboveground is warm in the summer, with highs often in the 90s (30s Celsius) and sometimes exceeding 100°F (38°C); evening lows are in the mid-60s (upper teens Celsius). Winters are mild, with highs in the 50s and 60s (10s and midteens Celsius) in the day and nighttime lows usually in the 20s and 30s (low negatives Celsius). Summers are known for sudden intense afternoon and evening thunderstorms; August and September see the most rain. Underground it's another story entirely, with a year-round temperature that varies little from its average of 56°F (13°C), making a jacket or sweater a welcome companion.

Seasonal Events

A "bat flight breakfast," planned from 5 to 7am on a summer Saturday at the Bat Flight Amphitheater, offers visitors an opportunity to have breakfast while they watch the bats return to the cavern after their night of insect hunting. Breakfast can be purchased at the restaurant near the visitor center. Call the park for the date, cost, and other details.

Avoiding the Crowds

The park is open year-round and receives more than 400,000 visitors annually. Crowds are thickest in summer and on weekends and holidays year-round; visiting on weekdays between Labor Day and Memorial Day is the best way to avoid them. January is the quietest month.

Visiting during the park's off season is especially attractive because the temperature in the caves stays the same regardless of the weather above -- 56°F (13°C). The only downside is that you won't be able to see the bat flights. The bats head to Mexico when the weather starts to get chilly, usually by late October, and don't return until May. There are also fewer guided cave tours off season. The best time to see the park might be September, when you can still see the bat flights but there are fewer visitors than during the peak summer season.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.