Minnesota Lake Ice-In and Ice-Out Widget

Minnesota Sea Grant (MNSG) Director John A. Downing wanted a tool for friends, colleagues, and family that they could use to better plan for spring activities. The tool, called the Minnesota Lake Ice-In and Ice-Out Widget, measures the thawing potential that weather exerts on lakes in spring.

The widget is a bit of science fun to show you how to estimate when a body of water like a lake is likely to freeze or thaw. It's a work in progress and we welcome your feedback.

Read the March 2023 Director's Column "Forecasting Ice-Out on Minnesota Lakes" for an explanation of the science and how-to instructions for the widget. 

• Disclaimer: This widget does NOT predict when ice is safe for you! 
• Safety: Your safety is your responsibility.
• Ice is never 100% safe and conditions can change rapidly.

Jargon Alert! We need to explain some science jargon. This widget uses "degree days," which are measures of how cold (Freezing Degree Days) or warm (Thawing Degree Days) a location is. It's helpful to remember that you can have more than one degree day in a 24-hour period. Degree days are the difference between the daily temperature mean (high temperature plus low temperature divided by two) and 65°F.

Degree days for a single (24-hour) day are calculated using the following formulas:

• Thaw Degree Days for a single day: [(High temp + low temp)/2] -32
• Freezing Degree Days for a single day: 32- [(high temp + low temp)/2] = FDD
• If the result of the formula is a negative number, then the answer is zero (0).