Weather & Agri-Tech

July 5, 2026

How to Use a Weather Station on Your Farm

Having a weather station on your farm is one thing. Knowing how to use the data it generates to make better farming decisions is another matter entirely.

Many farmers who install weather stations initially look at the numbers and are not sure what to do with them. This guide tells you exactly which readings to monitor, what they mean for your farm operations, and how to translate raw weather data into practical daily decisions.

What a Farm Weather Station Measures

A standard agricultural weather station measures some or all of the following:

Parameter	What It Measures	Farming Use
Air temperature	Ambient air temperature (C or F)	Frost risk, heat stress, pest/disease development, irrigation timing
Relative humidity	Moisture content of air as percentage	Disease risk assessment, irrigation scheduling, spray timing
Dew point	Temperature at which air moisture condenses	Leaf wetness estimation, frost risk refinement
Rainfall	Amount of precipitation in mm	Irrigation adjustment, drainage planning, runoff monitoring
Wind speed	Speed of wind (km/h or m/s)	Spray go/no-go decisions, crop lodging risk
Wind direction	Compass direction of wind	Spray drift management, smoke and disease spore source tracking
Solar radiation	Incoming solar energy (W/m2)	Evapotranspiration calculation, photosynthesis potential
UV index	Ultraviolet radiation intensity	Bio-pesticide application timing, worker safety
Soil temperature	Temperature at 10 cm or other depth	Planting timing, biological activity, root zone health
Leaf wetness	Duration of free water on leaf surface	Fungal disease risk calculation

The Five Most Important Daily Readings for Farmers

1. Minimum Overnight Temperature

Check the overnight minimum every morning. This single number tells you:

Whether a frost event occurred: Any reading at or below 0 degrees Celsius means frost occurred. Check your sensitive crops.
Growing degree day accumulation: GDDs are calculated from daily temperature data. They tell you where your crops are in their development cycle and when pest and disease thresholds will be reached.
Chilling accumulation: Fruit tree dormancy and bud break timing are governed by accumulated chilling hours (hours below 7 degrees Celsius). Your station records this automatically.

Use accumulated growing degree day data from your station with the Growing Degree Days Calculator to track crop development milestones and predict harvest timing with precision.

2. Daily Reference Evapotranspiration (ET0)

ET0 is the single most useful output your weather station can generate for irrigation management. It tells you exactly how much water the crop environment used yesterday, based on temperature, humidity, wind, and solar radiation.

Irrigation need = Crop ET (ET0 x crop coefficient) minus effective rainfall

Running this calculation daily from your station data tells you with precision when to irrigate and how much to apply. This eliminates both under-irrigation (yield loss) and over-irrigation (wasted water, root disease, nutrient leaching).

The Evapotranspiration Calculator processes your station readings into a daily ET0 figure that you can directly use for irrigation scheduling.

3. Rainfall Amount and Intensity

Your rain gauge data lets you:

Adjust or skip irrigation: If 20mm of rain fell overnight, your planned irrigation is likely not needed today.
Track seasonal totals: Comparing cumulative season rainfall against historical averages tells you whether you are in a dry or wet spell and what that means for the coming weeks.
Monitor intensity: High-intensity rainfall (above 20mm per hour) indicates runoff and erosion risk rather than absorption. It also signals potential soil compaction and need for aeration.

4. Wind Speed and Direction

Your station’s wind data is your spray go/no-go decision tool. Check average wind speed and gusts for the coming spray window:

Below 8 km/h average with gusts under 12 km/h: Green light for spraying.
Average 8 to 16 km/h: Proceed with caution using drift-reducing nozzles.
Any gusts above 20 km/h: Wait. Spray drift in these conditions is significant.

Combine your station wind data with the Weather-Based Spray Scheduler to get a combined risk assessment for spray operations that also factors in temperature and rain probability.

5. Relative Humidity and Leaf Wetness Duration

These two parameters together define your disease risk profile. Most fungal crop diseases require specific humidity thresholds and a minimum period of leaf wetness to complete infection cycles.

Practical decision rule: If relative humidity has been above 80 percent for more than 8 to 12 consecutive hours (particularly overnight), your disease risk has increased significantly. Inspect crops and consider preventive fungicide application for susceptible crops.

If your station has a leaf wetness sensor, this becomes even more precise. Record cumulative leaf wetness hours per day. When combined with temperature data, you can calculate infection periods for specific diseases (e.g., Mills Table for apple scab, Smith Period for potato late blight).

Using Station Data for Pest and Disease Modeling

The most sophisticated use of farm weather station data is integration with pest and disease development models. These models use temperature data to predict when specific pest or disease events will occur.

Examples:

Degree-day models for insects: Most insect pests have specific thermal requirements for each life stage. By accumulating degree-days from your station data, you can predict when egg hatching, larval emergence, or adult flight periods will occur, allowing precise timing of control measures.
Blight models for potatoes: The Blight Severity Value (BSV) model uses temperature and relative humidity data from your station to calculate daily infection risk. When BSV accumulates beyond a threshold, fungicide application is triggered.
Powdery mildew risk index: Daily temperature range and humidity data from your station can be used to calculate powdery mildew risk for vine, vegetable, and cereal crops.

Sharing Your Data With Apps and Platforms

Most modern weather stations can upload data automatically to online platforms where it integrates with weather apps, disease models, and agricultural management software.

Weather Underground Personal Weather Station network: Upload your station data and it becomes available to other farmers and apps in your area.
Netatmo: Connects to Weather Underground and other platforms automatically.
Davis Instruments stations: Integrate with WeatherLink cloud platform, which offers agricultural-grade data analysis tools.

When you upload your data, you also contribute to the regional network that makes hyperlocal forecasts more accurate for everyone.

Building a Station Data Log

For the richest decision-making value, maintain a simple daily log alongside your digital data. Write down the daily max and min temperature, rainfall, any pest or disease observations, and any farm operations performed. After two to three seasons, this log becomes one of the most valuable documents on your farm.

Pattern recognition from your own data is irreplaceable. You will start to notice correlations specific to your farm and microclimate that no weather service can tell you: the south-facing block always gets frost three days earlier than the main field, or heavy rain in April always causes aphid population collapses in May.

Frequently Asked Questions

Do I really need a weather station if I have a good weather app?

Weather apps use the nearest meteorological station or forecast model, which may be 20 to 50 km from your farm. A farm weather station gives you actual measured data at your location, which is significantly more accurate for irrigation, spray timing, and disease management decisions.

How often should I check my weather station data?

Twice daily is the practical minimum: in the morning to see overnight conditions and set the day’s plan, and in the evening to record the day’s readings. Many farmers check hourly data via connected apps throughout the day for spray windows.

What is ET0 and how do I use it for irrigation?

ET0 (reference evapotranspiration) is the amount of water evaporated and transpired by a reference grass crop under current weather conditions. Multiply ET0 by your crop’s coefficient (Kc) and subtract any rainfall to get your daily irrigation requirement.

Can a cheap weather station give useful data?

Yes. Even a basic $50 to $80 station measuring temperature, humidity, rainfall, and wind gives you the most critical parameters for spray timing and frost protection. Accuracy improves with price, but the decision value starts at even the basic level.

How do I calculate disease risk from my station data?

Disease risk models use temperature and humidity data from your station. Some platforms like Agrimeteo integrate station data with disease models automatically. For manual calculation, look up the specific temperature/humidity requirements for the disease you are monitoring.