About GDD-Pro

GDD-Pro is a web application being built to help farmers, agronomists, researchers, and agricultural enthusiasts track and analyze Growing Degree Days (GDD) for agricultural planning and decision-making.

What are Growing Degree Days?

Growing Degree Days (GDD) measure accumulated heat units above a base temperature, helping predict plant development stages, pest emergence, and optimal timing for agricultural operations. GDD tracking is essential for:

• Predicting crop development stages (emergence, flowering, maturity)
• Timing pest management interventions
• Scheduling irrigation and fertilizer applications
• Comparing growing seasons year-over-year
• Research and variety trials

How GDD is Calculated

These daily GDD values accumulate throughout the growing season to provide a cumulative heat unit total that helps predict crop development stages.

Base Temperature varies by crop and represents the minimum temperature required for growth. Common examples include 50°F for corn and soybeans, 40°F for wheat and peas, and 32°F for cool-season crops like spinach. Below the base temperature, plant development essentially stops.

Modified GDD (MGDD) adds an optional maximum temperature cap (e.g., 86°F for corn). Above this threshold, additional heat doesn't accelerate growth and may cause plant stress. This maximum is crop-specific and not used for all calculations.

Calculation Methods: GDD-Pro supports both the Standard (Average) method shown above and the Sine Wave method, which models the daily temperature curve more accurately by accounting for the continuous rise and fall of temperature throughout the day. The Sine method requires high-quality minimum and maximum temperature data and is generally more accurate for research applications.

Why GDD-Pro?

Agricultural planning requires reliable weather data and accurate GDD calculations. While university extension services and regional tools exist, they often have limited geographic coverage and variable sophistication. GDD-Pro aims to provide a modern GDD tracking tool with global data coverage and consistent features designed to be accessible to growers and researchers anywhere.

Who It's For

GDD-Pro is being developed for the agricultural community:

• Commercial Farmers: Time operations like planting, spraying, and harvesting based on accumulated heat units
• Agricultural Researchers: Analyze multi-year trends and validate variety trials with historical comparisons
• Extension Agents: Explore data-driven tools for growers in your region
• Agronomists: Monitor multiple locations and experiment with threshold-based alerts for critical growth stages
• Home Gardeners: Track your growing season and learn about GDD-based planning

Data & Accuracy

GDD-Pro uses trusted weather data sources and standard calculation methods:

• Data Source: NOAA Global Historical Climatology Network daily (GHCNd) weather observations
• Historical Depth: Up to 30 years of records available for trend analysis and percentile comparisons
• Station Coverage: 10,000+ weather stations across North America and globally
• Daily Updates: Weather data is refreshed automatically
• Calculation Methods: Standard (average temperature) and Sine Wave methods with data quality checks
• Interpolation: Missing data points are handled with linear interpolation where appropriate

Note: While we use established data sources and calculation methods, we're still validating accuracy across different regions and use cases. Please verify critical agricultural decisions independently.

Beta Program

GDD-Pro is currently in beta with full access to all features at no cost. Your feedback during this period helps us prioritize features, improve accuracy, and build tools that solve real problems.

Our goal: It's our goal to always offer free tiers. Guest charts (no account required) and free accounts are designed to keep core GDD tracking accessible to everyone in the agricultural community. Premium features will be introduced as we exit beta, but our intent is to keep basic GDD calculation and visualization free.