Synchronous Fireflies: Your Guide to the Great Smokies’ Annual Light Show in 2025

Up and down the Eastern US, fireflies (or lightning bugs) are an essential part of summer nights, twinkling against the dark sky as they search for a mate. But in certain pockets of the Southeast, the unique synchronous firefly (Photinus carolinus) puts on an extraordinary summer display. In large enough populations, these fireflies will all flash the lanterns on their abdomens at the same time, then go completely dark for 6 seconds—lighting up the forest and creating a spectacular visual experience that can’t be captured on camera. 

What are synchronous fireflies?

Though there are many species of fireflies in North America, synchronous fireflies are unique because of their distinct flash pattern, alternating bright light with moments of total darkness for hours on end. This is all part of their mating ritual—after roughly a year of crawling around the forest floor as larvae, adult fireflies only have 21 days to find a mate. Male fireflies zoom around hardwood forests, flashing in perfect harmony, and female fireflies respond from the ground with two quick blinks to mark their location.

When can I see synchronous fireflies?

These fireflies have different mating seasons throughout the summer depending on their exact location, but they’re generally active from late May through early June. The largest and most well-known firefly event occurs in Great Smoky Mountains National Park around the first week of June. The best time of day to view the fireflies is right after dark, usually from about 9pm to midnight.

Tips for viewing synchronous fireflies

As synchronous firefly viewing events have grown in popularity, it’s increasingly important to follow guidelines to help protect this insect. Try a red-light headlamp, or, if you bring a flashlight, cover it with red or blue cellophane, as regular light can confuse the fireflies’ natural rhythm. Point your flashlight at the ground, and turn it off when you arrive at your viewing spot. Do not catch fireflies, and be sure to stay on the trails so as not to disturb their habitat. Always remember to recreate responsibly and leave it better when spending time outdoors.

Where are the best places to see synchronous fireflies?

The largest population in the Western Hemisphere is situated near the northern edge of Great Smoky Mountains National Park in Tennessee and parts of the park in North Carolina. The region has drawn international attention over the last few years from visitors hoping to see one of nature’s best light shows. Read on to discover where to see them this year!

Elkmont Campground, TN

Elkmont Campground is the most well-known location for viewing synchronous fireflies, and for good reason. Every year, the Elkmont area attracts thousands of fireflies that put on a dramatic light show, and in 2025, the park’s planned event dates are slated for Thursday, May 29 through Thursday, June 5, an 8-day period.

Be warned, this show is an exclusive one—the National Park Service only issues coveted Elkmont parking passes on a lottery basis. These passes secure access for up to 7 people per vehicle to the Elkmont fireflies viewing location for the event, and only 960 parking passes are available (120 per day, down 20% from 2024). The firefly viewing lottery is now closed.

And even if you don’t win a ticket this time around, you can consider visiting Elkmont in the days before or after the regulated viewing. While there is no guarantee that you will see fireflies outside of their peak mating dates, there is a chance you’ll spot some early bloomers or fashionably late bugs.

Can’t get Elkmont tickets? You can still see the fireflies at these spots in and around the Great Smoky Mountains.

Rocky Fork State Park, TN

Score a ticket to Rocky Fork State Park‘s firefly light show, and you’ll get the chance to see both synchronous fireflies and blue ghost fireflies in one incredible event. Like other parks on this list, Rocky Fork State Park has implemented a lottery system, only allowing eight vehicles per night to view the show. Find out more about the chance to win on their website.

Joyce Kilmer Memorial Forest, NC

Joyce Kilmer is famously one of the most impressive old-growth forests in the country, but its high density of hardwood trees also makes it an ideal habitat for synchronous and blue ghost fireflies. The only way to see the forest is on foot—walk along the 2-mile trail looping through 400-year-old trees and find a bench to post up and watch fireflies light up the night. Nearby, Nantahala National Forest‘s Horse Cove Campground can be a good place to camp.

Congaree National Park, SC

South Carolina’s Congaree National Park held its first Firefly Festival in 2017. By 2019, the event had grown into an 18-day celebration attracting more than 12,000 visitors from around the world. To limit numbers and protect fragile firefly habitat, the Congaree viewing event now limits attendance to just a few days and uses a lottery system for nightly vehicle passes. Congaree firefly viewing is set to be open Wednesday, May 14 to Wednesday, May 21, 2025.

The lottery has already ended, but if you didn’t score a ticket to the official Congaree fireflies event, try visiting the park in the days right before or after. Just be sure to check guidelines at the official park website, as there are increased visitor regulations throughout May.

Cataloochee Valley, NC

Synchronous fireflies (and the otherwordly blue ghost fireflies) have also been spotted throughout the Cataloochee Valley, but they are harder to find in this remote part of the national park, where the gravel entrance road can be treacherous: It’s narrow and winding with some steep dropoffs with no guard rails. Park officials advise visitors to stick with the Elkmont area for your own safety and the sake of the firelies. Those who choose to venture here should exercise extreme caution if choosing to drive this road at night.

Cades Cove, TN

Roughly an hour west of Elkmont inside Great Smoky Mountains National Park, Cades Cove is also known to host fireflies around the Abrams Falls trailhead for their mating season, though you shouldn’t plan to go here after dark. The main gate to Cades Cove Loop Road closes at sunset—this is when you should make your way out to avoid creating challenges for park rangers. On Wednesdays, this road is entirely closed to vehicles and only open to bike and pedestrian traffic.

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