This is a simple sketch that displays the coldest temperature measured on the NeoPixels.
With this sketch loaded and running on the Circuit Playground, you can place it somewhere and let it sit. It will continuously read the current temperature and keep track of the coldest (minimum) temperature measured.
The freezer compartment of your refrigerator is a convenient place to try. Leave the Circuit Playground in the freezer for at least 30 minutes to insure it cools all the way down.
When you retrieve the Circuit Playground, it will show the minimum temperature seen on the NeoPixels. You can select either Fahrenheit (+, left) or Celsius (-, right) using the slide switch. Then, use the diagram below to determine the value.
You come up with the temperature by adding up the value shown for each NeoPixel that is lit. For example:
To clear the minimum temperature value and start over, just press RESET.