Spraying windows: why looking at one variable is not enough

Before spraying, checking the forecast may seem like a simple task. Wind. Rain. Humidity. Temperature. The problem begins when each variable tells a different story. Wind may be light, but rain may be forecast a few hours later. There may be no rain, but the wind may be stronger than is advisable. One part of the day may be unfavorable, while conditions a few hours later may be considerably better. That is why looking at a single variable is rarely enough when deciding when to spray.

What is a spraying window?

A spraying window is a period when weather conditions are more favorable for an application. It does not depend on a single number. It comes from analyzing several variables at the same time and observing how they change hour by hour. In Vienor, spraying windows combine weather information to classify each period according to the forecast conditions. The idea is quite simple:

Instead of reviewing each data point separately, identify the hours when the overall conditions are more suitable.

Wind is one of the main variables

Wind plays a central role during an application. But it is not enough to ask whether it is “windy” or “not windy.” Wind speed can change considerably throughout the day. A morning may begin with calm conditions and become much less favorable only a few hours later. Vienor analyzes the hourly forecast and uses wind as one of the variables that determine a spraying window's status. This makes it possible to detect periods when conditions improve or deteriorate without relying only on a daily summary.

Rain can matter even before it starts

Another common situation is finding good conditions at the time of application but forecast rain shortly afterward. If you only look at the current sky, that information is not visible. If you only look at the chance of rain for the entire day, you still may not know when it is expected. That is why spraying windows account for precipitation forecast over the following hours. The goal is to analyze not only what is happening now, but also what may happen after the application.

Humidity also changes the picture

Relative humidity is one of the conditions Vienor uses to evaluate spraying windows. And, as with wind and rain, it does not remain the same throughout the day. It can change significantly between the early morning, daytime, afternoon, and night. When several variables are considered together, windows emerge that may not be obvious when looking at a single data point.

The problem with looking at the forecast “for the day”

Daily summaries are useful for getting a general idea. But a specific task takes place at a specific time. Knowing that tomorrow will have:

A high of 22 °C

Moderate wind

A 30% chance of rain

is not necessarily enough to decide whether to spray at 8 a.m., 11 a.m., or 4 p.m. The useful information lies in how those conditions change during the day. That is why Vienor works with hourly data.

A traffic-light system to reduce noise

Vienor's spraying windows present conditions in three levels:

Green

Yellow

Red

The purpose is not to replace agronomic judgment or the specific instructions for the product being applied. It is to simplify the interpretation of weather information. Instead of manually comparing several forecast columns, you can quickly identify which hours have more favorable conditions and which require greater attention.

A favorable window does not mean “go ahead and spray”

This is an important point. Vienor analyzes weather conditions. It does not know every agronomic variable involved in a particular application. The crop, product, dose, equipment, label restrictions, field conditions, and decisions of the responsible professional all remain decisive. A green window should therefore be understood as:

The weather conditions evaluated are favorable according to the system's criteria.

It is not automatic authorization to carry out an application.

Why not use only a wind alert?

Because it answers a different question. A wind alert detects when one variable exceeds the threshold you configured. A spraying window considers several conditions at the same time. They are complementary tools. The alert can tell you:

Gusts will exceed the value you defined.

The window can help you see:

Which hours present a more or less favorable combination of conditions for spraying.

Conditions change throughout the day

One of the main advantages of working hour by hour is the ability to find short periods that may be lost in a general forecast. The morning may appear yellow. Midday may turn red. And the afternoon may return to green. That does not mean the forecast is contradictory. It means the variables are changing. Vienor organizes that evolution to make it easier to see.

You do not need to reconstruct the window manually

You could open a forecast and compare:

Wind

Humidity

Chance of precipitation

Forecast rainfall

Then you could move through the forecast hour by hour to find the best time. The information is available. The problem is the effort required to interpret it repeatedly. Spraying windows automate that work. Vienor retrieves the forecast, evaluates the conditions, and presents a summarized result.

Weather as part of a decision, not just another screen

A weather tool can display a large amount of data and still leave all the interpretation to the user. Spraying windows follow a different logic. The data is still there, but it is organized around a concrete question:

What do the next few hours look like for an application?

That difference matters. It is not about placing more variables on the screen. It is about making those variables easier to use.

Check spraying windows in Vienor

Vienor analyzes the hourly forecast for your fields and combines different weather conditions to show favorable, marginal, or unfavorable periods for spraying. The forecast updates automatically, and conditions are reevaluated every 30 minutes.

Try Vienor free for 30 days, with no credit card required.