Online Phenology Models and Degree-day Calculator


This phenology model/degree-day calculator uses weather data to calculate degree-days, also known as heat units that are used to estimate development of many organisms, such as insects and plants.

This app is a re-designed, mobile-friendly, member of a family of online model/calculators at: USPEST.ORG (home page). The numerous models served by this app are all driven only by daily maximum and minimum temperatures, using one of many different degree-day calculation formulas, many of which are described at this UC Davis IPM website. Note that this app requires an internet connection and will not work in airplane or off-line mode.

Instructions for Use

The Station Tab

The Model Tab

The Output Tab

The Graph Tab

Email Subscriptions


Weather Station

Currently selected:
Uploaded weather data needs to be in a specific format; see the format description and example files.
  • :
Weather data is normally from a station, but you can upload your own if you prefer.


Select the "Model" tab to choose the model to use and related details.

Species / Model

Select a model or species. (see list of models) To choose your own calculation method and threshold temperatures, chose "degree-day calculator".





  • info : after 7 days, use
  • :

Ignore this blank; it's not supposed to be displayed.


That's all the necessary input. From here, you can study the model details below, or go to the "Output" and "Graph" tabs for your model output.

Model Inputs

Date Comparison

Model Output

All data provided "as is" and users assume all risk in its use - see full disclaimer. All NWS derived data is not subject to copyright protection.

This app is produced by at the Integrated Plant Protection Center at Oregon State University with support from the USDA National Plant Diagnostic Network, The OSU Agricultural Experiment Station, various USDA CSREES/NIFA grants, USDA SARE, USDA RMA, and USDA IPM Centers - Western Region. Climate map data provided by OSU PRISM Group, real-time public weather data provided by U. Utah Mesowest and other networks including WSU AgWeatherNET, AGRIMET, CPS Adcon Networks, IFPNet Automata, California CIMIS, California PestCast, and others. Geo-coding (location search using place names) by OpenCage, using data © OpenStreetMap contributors.

Previous versions online since May 16, 1997; this is app version 0.95, updated 18 Nov 2022

Contact Len Coop at or 541-737-5523 if you have any questions about this program.