x
Breaking News
More () »

What is a leap year? Everything you need to know

Leap years occur every four years. But why? 12News meteorologist Lauren Rainson explains.

PHOENIX β€” Thursday, Feb. 29, 2024, is a leap day. So what exactly is a leap day and leap year? 

It has to do with the number of days in a year and the time it takes for the Earth to complete one orbit around the sun, which is 365 days. Well, technically, it's 365.2422 days.

So what's the deal with that extra .2422? That quarter of a day needs to be accounted for somewhere otherwise in 100 years, the calendar would be off by four weeks.

This is why we add an extra day to the calendar once every four years. Problem solved? Well, not entirely. By simply adding one extra day to the calendar every four years, we'd still be off by 18 hours in 100 years.

To correct this problem, we look at the century years. Not all century years are leap years. Only one in four century years are leap century years. For example, the years 1700, 1800, and 1900 were skipped. The year 2000 was a leap year. A century year must be divisible by 400 (evenly divided by 400) in order to be a leap century year. 

Now, with all this in place at this rate it would take over 3,000 years for us to be off by one day. Still not completely perfect, but this is why we observe leap years mostly every four years.

>> Download the 12News app for the latest local breaking news straight to your phone.

Watch 12News+ for free

You can now watch 12News content anytime, anywhere thanks to the 12News+ app! 

The free 12News+ app from 12News lets users stream live events β€” including daily newscasts like "Today in AZ" and "12 News" and our daily lifestyle program, "Arizona Midday"β€”on Roku and Amazon Fire TV. 

12News+  showcases live video throughout the day for breaking news, local news, weather and even an occasional moment of Zen showcasing breathtaking sights from across Arizona. 

Users can also watch on-demand videos of top stories, local politics, I-Team investigations, Arizona-specific features and vintage videos from the 12News archives. 

RokuAdd the channel from the Roku store or by searching for "12 News KPNX." 

Amazon Fire TV: Search for "12 News KPNX" to find the free 12News+ app to add to your account, or have the 12News+ app delivered directly to your Amazon Fire TV through Amazon.com or the Amazon app.

12News on YouTube

Arizona has seen its fair share of severe weather. Here is a compilation of videos from various storms across the Grand Canyon state.

Before You Leave, Check This Out