Free growing degree days calculator
Add up growing degree days from your biofix date, project the next seven days, and find spray windows with low wind and no rain.
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How do you calculate growing degree days?
For each day, average the high and low temperatures and subtract your pest or crop model's base temperature, counting zero when the result is negative. Add the days up from the biofix date. This tool does that from weather station data and projects the next week.
Fill in the prompt
Edit the details in brackets with the field location, the pest, its biofix date and the model's base temperature, then pick the AI assistant to run it in.
Firecrawl Alexandria runs the lookups
Your assistant calls 4 tools in order, from ACIS (NOAA Regional Climate Centers), National Weather Service API (api.weather.gov) and NASA POWER, and cites the record behind every figure.
Get the answer
You get degree days so far and projected by day, the date the model's threshold is reached, and spray windows by date and hour. Anything a source couldn't find is marked, not guessed.
Who is the free growing degree days calculator for pest timing for?
Anyone timing field work by accumulated heat.
Crop consultants
Time scouting and insecticide applications to your pest model's thresholds.
Growers
Know when a pest is due and which days this week have spray windows.
Extension agents
Run the same degree-day check across several fields.
Where does the data come from?
From the sources below, called in order through Firecrawl Alexandria. Each row shows the call's price in credits and its track record across every agent. Empty means the call worked and found nothing.
ACIS (NOAA Regional Climate Centers)Daily weather historyPrice5 creditsMedian–Success–Empty–
National Weather Service API (api.weather.gov)Forecast dailyPrice5 creditsMedian227 msSuccess100%Empty0%
NASA POWERDaily weatherPrice5 creditsMedian–Success–Empty–
What steps does the assistant follow?
The tool's written instructions: which data source to call at each step, what to pull from it and how to lay out the answer. Copy them into any assistant connected to Firecrawl with an API key to run the tool from your own chat.
Explore more free tools
Ready-made prompts for ChatGPT, Claude and other assistants, each backed by the data sources it names.
Frequently asked questions
- Which base temperature should I use?
- The one your extension pest model uses. The tool doesn't supply bases or thresholds, so take both from your model.
- Where does the weather data come from?
- Daily station history for the degree days so far, and the National Weather Service forecast for the next week and for hourly spray windows.
- Is this tool free?
- Yes. The prompt, the steps and the instructions are free to use. When your assistant runs the tool through Firecrawl Alexandria, each data call bills its listed price in credits, and every data source shows that price before it's called.
- Which AI assistants can run it?
- Any assistant connected to Firecrawl with an API key, including ChatGPT, Claude, Claude Code, Codex and Cursor. Pick one in the prompt box and your request opens there with a link to this tool.
- Do I need to sign up?
- You need a Firecrawl account, with your assistant connected through its API key. Firecrawl Alexandria doesn't run in keyless mode. If your assistant isn't connected yet, the prompt tells it how to set that up. Some data providers ask an admin on your Firecrawl team to accept their terms before the first call.