The different temperatures humans experience can be as localized as the variance from a suburban area to its urban center. The urban heat island effect – UHI for short – is one such danger. Cities are hotter due to concrete and asphalt absorbing and retaining heat, less tree cover, AC units pumping out hot air, and more. Most worrisome is how hot it remains at night, when bodies are trying to cool down and recover from hot daytime temps. Scientists like Angel Hsu are using data collected by satellites and citizens to translate these urban effects into numbers policymakers can use when leading climate change mitigation efforts on local levels.