PearX alums WindBorne closed a $6 million round to improve forecasts and mitigate the climate crisis with smart weather balloons

June 27, 2023

Fundraising , Founder Stories


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Last week, PearX S19 alum WindBorne Systems announced their $6M seed round led by Footwork Ventures and joined by Pear, Khosla Ventures, and others. We love WindBorne’s founding story as it embodies everything we believe at Pear about mission-driven, high perseverance founders. 

I was lucky to meet the founders of WindBorne back in the spring of 2019, when they were undergraduate students at Stanford University. They showed up to my office hours with a balloon in tow, similar to the one pictured below. 

Early prototype of a WindBorne balloon

I had no idea that the homemade-looking device was a low cost, highly durable weather balloon that could fly at a wide range of altitudes. They called this balloon ValBal for (Vent to sink, Ballast to rise).

We decided to partner with WindBorne for two reasons:

  • First, we believed in the founding team. They had demonstrated a clear mission, a strong passion, and an incredible ability to execute. They’d been addicted to this idea since they were freshman at Stanford as members of the Stanford Student Space Initiative. Constrained by a student budget, they used ingenuity and engineering to build weather balloons that would fly for a few hours and then pop. Over the years, they kept adding sensors and extending flight time, steadily improving their product. By the time I met them, they had already completed 26 test flights and broken four world records. 
Map of flight tests the WindBorne team conducted while in college
  • Second, they were capturing data that no one else was capturing. At the time, we were not 100% sure of the value of such data, but after making a few calls, we discovered potential customers were interested in learning more about what the balloons could do. 
WindBorne team testing balloons during their time at Stanford

With that, we invited WindBorne to join PearX’s Summer 2019 cohort, where we partnered closely with the founders to understand the most attractive market opportunity to go after. Through customer interviews, they discovered a massive data gap: only about 15% of the Earth’s surface has regular in-atmosphere observations, but weather is a global system. To better predict the weather, you need better weather data. Existing technologies couldn’t plug that gap, because the laws of physics prevent satellites from collecting the most critical weather observations. That’s where balloons come in: they’re able to collect data where satellites can’t.

Kai during PearX Summer 2019

Investors were convinced of the potential, and following S19 Demo Day, Windborne closed a successful seed round led by Khosla and Ubiquity Ventures. They spent the last four years growing the company: from iterating on their go-to-market strategy to team building to customer interviews to strategy sessions and more. We had the privilege to work side-by-side with John, Kai, Joan, Andre, and the entire WindBorne team every step of the way.

WindBorne team at PearX 2019 Demo Day

Last fall, the WindBorne team went out to begin raising their next round, in the midst of a tough economic climate. As PearX alums, we invited them to participate in our PearX S22 Demo Day, where Kai shared the latest happenings with thousands of investors in the Pear network. We’re so proud of the entire team for this next step in their journey.

PearX S22 Demo Day Presentation

I recently visited the new WindBorne HQ in Palo Alto, just a few weeks after the team moved in, and I left with a smile on my face. The offices were scrappy, the team was as determined as ever, and they were telling me all about the new advances with their product. I couldn’t help but look back and remember the first time they ever walked into my office as Stanford students and feel proud of how far they’ve come. I know this is just the beginning for WindBorne. We are so excited to continue to partner with them and to welcome Footwork and others to the team.