Agriculture API method returns farming indicators for any location for up to 14 days ahead, in json or xml: growing degree days (GDD), rainfall, reference evapotranspiration (ET0) and crop water use, water balance, chill hours, frost and heat stress hours, leaf wetness, disease risk, potato blight Smith Periods and hour-by-hour spray windows with Delta-T.
Choose a crop to use its default base temperature and crop coefficient, or set your own. Pass a season start date to get season-to-date totals from our historical weather. Data is hourly for the first 5 days and 3 hourly after that.
Available on Business plan and above. Keys on other plans receive error code 2009. The daily soil block is included for Enterprise plan users.
Example request
https://api.weatherapi.com/v1/agriculture.json?key=<YOUR_API_KEY>&q=52.2,0.12&days=7&crop=wheat&season_start=2026-03-01
Request parameters
| Parameter |
Required |
Description |
| key |
Yes |
Your API key. |
| q |
Yes |
Location. Same formats as other APIs. Lat,lon of the field is recommended. |
| days |
No |
Number of forecast days, 1 to 14. Default 1. |
| crop |
No |
Crop preset that sets gdd_base, gdd_upper, kc and heat_threshold: wheat, barley, maize (or corn), soybean, potato, rice, cotton, tomato, sunflower, grape or none. Default: none (reference grass, base 10 °C). |
| gdd_base |
No |
Base temperature for growing degree days in °C, -10 to 40. Default from crop. |
| gdd_upper |
No |
Upper temperature cut-off for growing degree days in °C, 0 to 50 and above gdd_base. Default from crop. |
| kc |
No |
Crop coefficient used for crop water use (ETc = ET0 x kc), 0 to 2. Default: FAO-56 mid-season value for the crop. |
| heat_threshold |
No |
Air temperature in °C at or above which hours count as heat stress, 15 to 50. Default from crop. |
| season_start |
No |
Season start date (yyyy-MM-dd) within the last 366 days. Adds season-to-date totals from historical weather up to yesterday. |
Crop presets
| crop |
gdd_base (°C) |
gdd_upper (°C) |
kc |
heat_threshold (°C) |
| wheat |
0 |
30 |
1.15 |
30 |
| barley |
0 |
30 |
1.15 |
30 |
| maize / corn |
10 |
30 |
1.20 |
35 |
| soybean |
10 |
30 |
1.15 |
35 |
| potato |
7 |
30 |
1.15 |
30 |
| rice |
10 |
30 |
1.20 |
35 |
| cotton |
15.6 |
32 |
1.20 |
35 |
| tomato |
10 |
30 |
1.15 |
32 |
| sunflower |
6.7 |
30 |
1.00 |
35 |
| grape |
10 |
35 |
0.85 |
35 |
| none |
10 |
30 |
1.00 |
32 |
The response contains the Location object, a crop object (the values used), a season object (when season_start is given) and a forecast object.
forecast -> forecastday: Parent element, one per day
forecastday -> day: daily totals and risks
forecastday -> hour: one element per forecast period
season element
| Field |
Data Type |
Description |
| start |
string |
Season start date |
| end |
string |
Last day included (yesterday) |
| days |
int |
Number of days with historical data |
| gdd |
decimal |
Growing degree days for the season so far |
| rain_mm |
decimal |
Rainfall in mm |
| et0_mm |
decimal |
Reference evapotranspiration in mm |
| etc_mm |
decimal |
Crop water use in mm (ET0 x kc) |
| water_balance_mm |
decimal |
Rain minus crop water use in mm (negative = deficit) |
day element
| Field |
Data Type |
Description |
| maxtemp_c / mintemp_c |
decimal |
Maximum and minimum air temperature in °C |
| gdd |
decimal |
Growing degree days for the day (capped-average method) |
| gdd_cumulative |
decimal |
Running total: season GDD (if season_start is given) plus forecast days so far |
| rain_mm |
decimal |
Rainfall in mm |
| et0_mm |
decimal |
Reference evapotranspiration (FAO-56) in mm |
| etc_mm |
decimal |
Crop water use in mm (ET0 x kc) |
| water_balance_mm |
decimal |
Rain minus crop water use in mm |
| chill_hours |
decimal |
Hours between 0 and 7.2 °C |
| frost_hours |
decimal |
Hours at or below 0 °C |
| hard_frost_hours |
decimal |
Hours at or below -2 °C |
| heat_stress_hours |
decimal |
Hours at or above heat_threshold |
| leaf_wet_hours |
decimal |
Hours with wet leaves (humidity 90% or more, or rain) |
| disease_risk |
string |
low, moderate or high. Generic fungal disease pressure from wet-leaf hours at 10 to 30 °C (6+ moderate, 10+ high) |
| smith_period |
int |
1 = Yes 0 = No
Potato late blight Smith Period: this day and the day before both had a minimum of 10 °C or more and 6+ hours of humidity 90% or more |
| spray_good_hours |
decimal |
Hours rated good for spraying |
| spray_marginal_hours |
decimal |
Hours rated marginal for spraying |
| soil |
object |
Enterprise only: soil_temp_5cm, soil_moisture_5cm, soil_moisture_25cm (m³/m³), paw (plant-available water) and workable_hours |
hour element
| Field |
Data Type |
Description |
| time_epoch / time |
int / string |
End of the period (unix UTC and local yyyy-MM-dd HH:mm) |
| period_hours |
decimal |
Length of the period: 1 for the first 5 days, 3 after that |
| temp_c, humidity, dewpoint_c |
decimal |
Air temperature, relative humidity and dew point |
| wind_kph, gust_kph |
decimal |
Wind speed and gust |
| precip_mm |
decimal |
Precipitation for the period in mm |
| et0_mm, etc_mm |
decimal |
Reference evapotranspiration and crop water use for the period in mm |
| delta_t |
decimal |
Delta-T in °C (air temperature minus wet-bulb temperature). 2 to 8 is the ideal spraying range |
| leaf_wet |
int |
1 = Yes 0 = No
Leaves likely wet |
| spray |
string |
good, marginal or poor |
| spray_reason |
string |
Why the period is not good: rain (rain now or in the next ~2 hours), wind (above 15 km/h, or above 20 km/h / gusts above 30 km/h for poor), evaporation (Delta-T above 8, or above 10 for poor), temperature (below 5 or above 30 °C), inversion_risk (wind below 3 km/h), high_humidity (Delta-T below 2). Empty when good |
Example response (shortened to two hours)
{
"location": {
"name": "London",
"region": "City of London, Greater London",
"country": "United Kingdom",
"lat": 51.52,
"lon": -0.11,
"tz_id": "Europe/London",
"localtime_epoch": 1791021600,
"localtime": "2026-10-03 11:00"
},
"crop": {
"name": "wheat",
"gdd_base": 0.0,
"gdd_upper": 30.0,
"kc": 1.15,
"heat_threshold": 30.0
},
"season": {
"start": "2026-09-23",
"end": "2026-10-02",
"days": 10,
"gdd": 140.0,
"rain_mm": 20.0,
"et0_mm": 20.3,
"etc_mm": 23.4,
"water_balance_mm": -3.4
},
"forecast": {
"forecastday": [
{
"date": "2026-10-03",
"date_epoch": 1790985600,
"day": {
"maxtemp_c": 18.0,
"mintemp_c": 6.0,
"gdd": 12.0,
"gdd_cumulative": 152.0,
"rain_mm": 0.0,
"et0_mm": 2.18,
"etc_mm": 2.5,
"water_balance_mm": -2.5,
"chill_hours": 5.0,
"frost_hours": 0.0,
"hard_frost_hours": 0.0,
"heat_stress_hours": 0.0,
"leaf_wet_hours": 1.0,
"disease_risk": "low",
"smith_period": 0,
"spray_good_hours": 17.0,
"spray_marginal_hours": 7.0
},
"hour": [
{
"time_epoch": 1791014400,
"time": "2026-10-03 09:00",
"period_hours": 1.0,
"temp_c": 12.0,
"humidity": 70.0,
"dewpoint_c": 6.0,
"wind_kph": 9.0,
"gust_kph": 14.4,
"precip_mm": 0.0,
"et0_mm": 0.066,
"etc_mm": 0.076,
"delta_t": 3.2,
"leaf_wet": 0,
"spray": "good",
"spray_reason": ""
},
{
"time_epoch": 1791028800,
"time": "2026-10-03 13:00",
"period_hours": 1.0,
"temp_c": 17.2,
"humidity": 53.0,
"dewpoint_c": 7.7,
"wind_kph": 9.0,
"gust_kph": 14.4,
"precip_mm": 0.0,
"et0_mm": 0.275,
"etc_mm": 0.316,
"delta_t": 5.6,
"leaf_wet": 0,
"spray": "good",
"spray_reason": ""
}
]
}
]
}
}
Notes
- Growing degree days use the capped-average method: the daily maximum is capped at gdd_upper and the minimum is raised to gdd_base.
- ET0 uses the FAO-56 Penman-Monteith method. Crop coefficients are FAO-56 mid-season values; set kc yourself for other growth stages.
- Disease risk is a generic indicator from leaf wetness and temperature, not a model for a specific disease. Spray ratings follow common label guidance; always follow the product label.