An agricultural weather station is a field-sited cluster of sensors that measures the local weather a crop actually experiences, rather than the conditions at a distant airport. Because so many farming decisions, from when to irrigate to when to expect a frost, depend on weather variables that vary field to field, having the measurements on-site turns weather from a forecast into hard local data. This guide inventories the sensor suite an ag weather station carries, explains how those feeds are used to compute reference ET and growing degree days on-site, and shows how telemetry pushes the data to a SCADA or agronomy platform for scheduling and frost alarms.
Agricultural Weather Station in one line: An agricultural weather station, sometimes called an agromet station, is a set of weather sensors installed in or beside a field to measure the local conditions relevant to farming. Its core sensors typically include a pyranometer for solar radiation, an anemometer and vane for wind speed and direction, sensors for air temperature and relative humidity, and a rain gauge, often with soil and leaf sensors added. From these measurements the station computes agronomic outputs such as reference evapotranspiration and growing degree days, and it telemeters the data to a scheduling or monitoring platform.
The value of an ag weather station lies in its sensor suite, and each instrument measures a variable that drives a farming decision. A pyranometer measures incoming solar radiation, the energy available to evaporate water and drive photosynthesis, which is the largest term in most evapotranspiration calculations. An anemometer measures wind speed, and often a vane adds direction, because wind carries moisture away from leaves and soil and strongly affects both water loss and spray drift. Air temperature and relative humidity are measured together in a shielded housing, since the difference between the air's actual moisture and how much it could hold sets the drying power of the atmosphere. A rain gauge, usually a tipping-bucket type, records rainfall, which is the natural water input that offsets irrigation need.
Beyond that core, agricultural stations commonly carry sensors that reach into the crop and soil rather than just the air. Soil temperature and soil moisture probes report what is happening in the root zone, leaf-wetness sensors detect how long foliage stays wet, which matters for disease, and a dedicated low-lying temperature or frost sensor watches for the cold that threatens sensitive crops. Some stations also measure barometric pressure and ultraviolet or photosynthetically active radiation. The exact configuration is tailored to the crop and the decisions it must support, but the unifying idea is that the station gathers, in one place and at the actual field, the full set of environmental variables that the agronomic models downstream will need.
Raw weather numbers become useful when they are combined into the agronomic quantities that guide decisions, and a capable station does much of this computation on-site. The headline output is reference evapotranspiration, ET0, which combines the radiation, temperature, humidity, and wind measurements through a physically based equation such as Penman-Monteith to express the atmosphere's demand for water as a daily depth. Because ET0 needs exactly the variables the core sensors measure, the station is essentially purpose-built to compute it, and having ET0 from the actual field rather than a regional estimate makes irrigation scheduling far more accurate for that specific site.
The other classic on-site computation is growing degree days, a running measure of accumulated heat that tracks crop development. Growing degree days are derived from the daily maximum and minimum air temperatures against a crop-specific base temperature, accumulating the warmth a crop has experienced, which predicts stages like emergence, flowering, and maturity better than the calendar does. A station that logs temperature continuously can compute and accumulate degree days automatically, giving the grower a live read on how far the crop has progressed thermally. Computing these outputs at the station, rather than only shipping raw data elsewhere, means the numbers a grower most wants are ready at the source and are based on the conditions the crop actually lived through.
A weather station in a field is only as useful as the operator's ability to see and act on its data, and that is the job of telemetry. Modern stations carry a cellular, radio, or satellite link that pushes their measurements and computed outputs off the field to a central platform on a regular cycle, so the grower does not have to visit the station to download it. This turns the station into a live feed rather than a data logger someone empties periodically, which is essential for the time-sensitive uses, since a frost warning is worthless if it arrives after the frost.
On a cloud SCADA and monitoring platform such as Merobix, the weather feed becomes a set of live tags trended alongside the irrigation infrastructure it informs, and this is where the station earns its keep. The computed ET0 flows straight into ET-based scheduling that sets pump run times, the rainfall reading credits the soil water balance so the system does not irrigate after a storm, and the frost sensor drives an alarm, and where wired to control, an automatic start of frost-protection pumps when the temperature crosses a setpoint. Because the platform sees the weather data and the pump and valve states together, it can act on the weather rather than merely display it: raising an alarm to phones when frost threatens, launching or holding an irrigation on the day's ET, and flagging a sensor that has stopped reporting. This is the same SCADA pattern of gathering distributed field instruments into one supervised, alarmed, and trended view, here applied to the weather that drives so much of what happens in the field.
The core suite is a pyranometer for solar radiation, an anemometer and vane for wind, temperature and relative humidity sensors, and a rain gauge. Agricultural stations often add soil temperature and moisture probes, a leaf-wetness sensor, and a low-lying frost or canopy temperature sensor. The configuration is chosen to supply the variables the farm's agronomic models, such as ET and disease or frost prediction, need.
It measures the radiation, temperature, humidity, and wind needed to compute reference evapotranspiration, the atmosphere's daily demand for water, right at the field. That local ET drives ET-based scheduling that sizes each irrigation to replace what the crop actually used, while the rain gauge credits any rainfall so the system does not irrigate ground a storm already wet. The result is watering matched to real local conditions rather than a fixed timer.
Growing degree days are a running total of accumulated heat, computed from daily maximum and minimum temperatures against a crop-specific base temperature. They track how much warmth a crop has experienced, which predicts development stages such as emergence, flowering, and maturity more reliably than the calendar. A weather station that logs temperature continuously can accumulate degree days automatically to show how far the crop has progressed thermally.
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