WhatAWeatherFrost risk · next 7 days
Traffic light based on the forecast daily minimum temperature at 2 m: ≤ 0 °C frost, 0-3 °C risk, > 3 °C no risk.
Water balance and irrigation
Reference evapotranspiration ET0 (FAO-56) vs precipitation, last 7 days and next 7. 1 mm = 1 litre/m².
Growing degree days (GDD)
| Day | Max T | Min T | Daily GDD | Cumulative GDD |
|---|
GDD are calculated as max(0, (Max T + Min T)/2 − base T). Accumulated over the past 7 days and projected 7 days ahead with the forecast. They help anticipate phenological stages (flowering, veraison, harvest) and pest cycles: compare the cumulative total with the tables for your crop and variety.
Treatment / spraying windows · next 48 h
Time slots with wind < 15 km/h, no rain forecast in the following 6 hours and relative humidity between 40 and 90 %.
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How to use this agrometeorological dashboard
Data comes from the Open-Meteo forecast API, which combines high-resolution weather models (ICON, GFS, ECMWF) for your exact coordinates. The dashboard covers 14 days: the last 7 observed/analysed and the next 7 forecast. Frost risk is assessed with the daily minimum at 2 m; remember that on clear, calm nights the temperature at plant level (radiative frost) can be 2-4 °C lower. The water balance compares reference evapotranspiration ET0 (Penman-Monteith FAO-56) with rainfall: the accumulated deficit guides your irrigation allocation, adjusted with the Kc crop coefficient of your species and phenological stage. Growing degree days accumulate useful heat above the base temperature and help anticipate phenology and pests. The spraying windows apply standard good-practice criteria: light wind to avoid drift, no rain so the product is not washed off, and moderate relative humidity for proper deposition.
Frequently asked questions
How is frost risk estimated?
We use the daily minimum temperature forecast by Open-Meteo at 2 metres: frost is likely with a minimum at or below 0 °C, there is risk with minimums between 0 and 3 °C (on clear nights the temperature at plant level can be 2-4 °C lower than the air temperature) and no risk above 3 °C. The approximate time is taken from the hourly temperature profile.
What is ET0 and how do I use it for irrigation?
Reference evapotranspiration (ET0, FAO-56 Penman-Monteith method) estimates the water lost by a well-watered reference crop, in mm/day. The water balance compares ET0 with rainfall: if accumulated ET0 exceeds precipitation there is a deficit, and each mm equals 1 litre per m². For your specific crop, multiply ET0 by its Kc coefficient.
What are growing degree days (GDD) and what are they for?
Growing degree days measure the accumulated heat useful for a crop's development: each day adds the mean temperature minus the crop's base temperature (if positive). A 4 °C base is used to track winter cereals; a 10 °C base for maize or vines. They help anticipate phenology: flowering, pests, grape harvest or crop harvest.
Can I decide on a phytosanitary treatment with this tool alone?
No. The spraying windows we show (wind below 15 km/h, no rain in the following 6 hours and relative humidity between 40 and 90 %) are indicative and based on a forecast model. Before treating, check conditions in the field, the product label, and consult your technical advisor.