Yes, you can visit Niagara Falls State Park (US side) and the Niagara Parks (Canadian side) 24 hours a day, 365 days a year, and viewing the falls themselves is completely free. The parks are beautifully illuminated every night (starting at dusk) and feature nightly fireworks from May through October. However, the specific attractions have strict operating hours. For example, the Maid of the Mist and Cave of the Winds typically operate from 9:00 AM to 4:00 PM or 8:00 PM depending on the season, and both close entirely during the winter months (reopening in May). In 2026, the Niagara Falls Visitor Center is usually open from 8:30 AM to 3:00 PM. If you visit in the "off-season" (November–April), the park remains a stunning winter wonderland with frozen mist coating the trees, but you will be restricted to viewing from the railings as the boat tours and boardwalks will be closed for safety. If you want the "classic" experience with all attractions open, visiting between June and August is essential, though it comes with the highest crowds.