Reference ET (Hargreaves) API

Computes reference evapotranspiration (ET0) by the Hargreaves-Samani equation from min/max temperature and extraterrestrial radiation, returning mm/day. Answers 'What is the reference ET for Tmin 15C, Tmax 30C, Ra 35 MJ?', 'How much irrigation water does the crop need?'.

Price$0.06per request

MethodPOST

Route/v1/climate/hargreaves-et

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

evapotranspirationet0hargreavesirrigationagronomywater-demandcropagriculture

API URLhttps://x402.hexl.dev/v1/climate/hargreaves-et

Integration docs

Example request

{
  "tMinC": 15,
  "tMaxC": 30,
  "raMJ": 35
}

Example response

{
  "et0MmPerDay": 5.128,
  "meanTempC": 22.5,
  "tempRangeC": 15,
  "raMJ": 35,
  "interpretation": "Reference crop water demand ≈ 5.13 mm/day.",
  "formula": "Hargreaves-Samani: ET0 = 0.0023·(Tmean+17.8)·√(Tmax−Tmin)·Ra / 2.45"
}

Input schema

{
  "type": "object",
  "required": [
    "tMinC",
    "tMaxC",
    "raMJ"
  ],
  "properties": {
    "tMinC": {
      "type": "number",
      "description": "Daily minimum temperature (C)",
      "examples": [
        15
      ]
    },
    "tMaxC": {
      "type": "number",
      "description": "Daily maximum temperature (C)",
      "examples": [
        30
      ]
    },
    "raMJ": {
      "type": "number",
      "description": "Extraterrestrial radiation (MJ/m2/day)",
      "examples": [
        35
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}