Four years ago we interviewed a 16-year-old high school student who had just created an online tool called the Snow Day Calculator to predict school closings, and ever since then that story seems to pop up in our most popular list whenever there's a snowstorm.

With Tuesday's massive storm moving toward Boston this week, the story resurfaced yet again. So, we wondered, whatever happened to David Sukhin and his snow day calculator?

We caught up with Sukhin Monday to find out.

Back then he was a junior in high school, and the website he created had been the culmination of a "pet project" he began as a sixth grader.

Now, Sukhin is a 20-year-old junior at MIT, where he is studying computer science and business. The snow day calculator now also exists as an app for iOS and Android.

And the snow day calculator is being used around the country, Sukhin said. On Sunday, ahead of the blizzard, 305,000 people accessed the calculator and the iOS app was downloaded 1,200 times, according to Sukhin. He said the calculator has received 38.5 million hits this month and 8,500 iOS downloads so far this winter.

Here's how the calculator makes its prediction: It uses an algorithm Sukhin created that analyzes a person's ZIP code, school type (public, private, etc.) and other factors, such as snow removal and a school's previous snow days. The tool also has the ability to learn from past predictions, Sukhin said.

We reached Sukhin by phone before the storm. He just finished a winter internship in Chicago and was stuck there since his flight back to Boston had been cancelled.

Here's what he had to say (lightly edited):

What have you been doing with the snow day calculator since you created it?

I've been trying to add as many features as possible. Some of the new things are school-based predictions, so the snow day calculator now can learn about a school's cancellation patterns and things like that based on previous snow days and how lenient a particular school might be. So, the schools in Boston might be a little easier cancelled than a school in Michigan and the snow day calculator is learning that and taking that into account.

What made you create the app?

A lot of people were definitely asking for it. The website is great if you're on a computer, but for on the go — which a lot of kids at school have their phones, but may not have their laptop — they want to pull it up and check the snow day calculator. That was why I created the app and it’s been a huge success. A lot of people have loved it.

What’s the reach of the snow day calculator? Who is using it?

Practically every U.S. state ZIP code has been typed in, including Hawaii. People sometimes just want to see if it’s really working and not just saying 99 percent everywhere. They type in [a] Hawaii ZIP code, they see sunny and 70 and no chance of a snow day [and] I guess they’re reassured. Practically every state is using it. Obviously the East Coast right now is pulling it up a lot more, but Colorado, the midwest, practically everyone.

How accurate is the snow day calculator?

It hasn't been wrong for my [middle and high] school. I love that, it's what I pride it on. I grew up on the East Coast so ... very similar areas like Boston, New York are also pretty wickedly accurate and that’s what keeps people coming back. The new features, the school features are mostly really to help with those northern Michigan schools that are used to 24 inches on a given day and can clean it up and send their kids to school, but I want to be sure to get them as accurate as possible too.

What’s the feedback you’ve been getting?

A lot of first time users are just like, “Whoa, it works. Awesome.” And they keep refreshing, they keep coming back to it, checking it. People tell their friends. Students rely on it to a point that I’ve heard them tell their parents, “Oh we’re not going to have school tomorrow for sure, so I’m not going to do my homework,” which might get me in some hot water for saying that. I would advise people to do their homework, but I’m happy that they trust it so much.

Do you plan to do more with the snow day calculator?

Absolutely, it’s been my pet project since 6th [and] 7th grade when it really began and I’ve been keeping up with it, making sure it’s running smoothly, adding new features that I think would be a cool thing to explore and a benefit to users. It has so much reach that I love keeping up with it, I love reading people’s emails for new ideas, feedback, accuracy and things like that.

There’s lots of ideas floating around. One of the most immediate ones that’s implemented is school administrators can sign up for the calculator and use it as a tool to blast to people’s phones [and] send emails to anyone signed up, but past that the calculator is also monitoring news sites trying to figure out what schools have already cancelled and using that as a way to report to itself and also to inform users very quickly as soon as there’s a cancellation.

What initially inspired you to create the snow day calculator?

It’s funny, I’ve been asked that so many times over the past few years. I do not remember why I initially sat down and created an app that predicts snow days. I think I was just kind of messing around and being like, "Hey, what can it be from the weather that's causing a snow day just for my school?" I was messing around [looking at] what time the snowstorm starts, what time it ends and created something that eventually kind of evolved to what it is now where anyone can type in any ZIP code they want and get a prediction for their school.

Have you made any changes to the calculator's algorithm since you created it?

The core algorithm, no. The real meat and potatoes of analyzing the weather and figuring out whether the main features for a snow day are in place, that’s been the same for almost eight years now. New things like those extra factors they’ve been tweaked. [I'm] also working on adding really cold temperatures. I know the Midwest has been having -40 degree mornings, which cause cold days and I’m working on getting those into the calculator as well.

So, you’re at MIT now, do you think the calculator helped you get there?

I’m sure it didn’t hurt. I think so, yes.

What would you like to do with a computer science degree?

To be honest I have not fully decided. The things I really enjoy are kind of right up the same alley as the snow day calculator. It’s predictive analytics-based, kind of using data to analyze and predict real world events and computer science is definitely very useful for that.

Do your friends and classmates at MIT know about your snow day calculator?

Yeah, a lot of people know. Sometimes, what’s really fun is they tell me about the snow day calculator because they remember using it in high school and I’m like, “Oh yeah, I know about that.” [laughs]

And do you tell them you’re the one who created it?

Oh yes [laughs]. That’s just how the conversation starts and it’s always funny.

What are you working on at MIT?

Lots of projects. [I’m] kind of spreading myself thin with things to do. Right now my main focus, I’m working with a hedge fund doing some data analysis. I’m kind of really spreading myself out and seeing what I like the best and seeing what sticks and seeing what I really want to pursue as I get out of school.

Do you plan to develop other types of tools and apps?

Absolutely, I’m always on the look out for things to explore in the same way [and] implement in the same way. I’ve implemented a few side projects for myself, but nothing has blossomed the same way as the snow day calculator and that’s the one I keep up with the most. But, I’m always exploring new things and always wanting to create something new. It’s very fun for me.

With the snowstorm, are you monitoring the activity with your calculator? How are you keeping up with this storm?

I spent the entire day [Sunday] monitoring the activity, answering people’s emails, questions. When it’s snowing it sort of becomes a full-time job, but that’s kind of the fun part. It’s great to see what people think, what the predictions are and making sure everything is working. I will definitely be on top of everything.