Laisha's weather is not a forecast app. A forecast tells you it will rain; this tells you whether the soil at rooting depth is already wet, whether the air is dry enough to be pulling water out of the crop faster than the roots can replace it, and whether the next seven days add up to a week you can spray, irrigate or harvest in.
It reads soil moisture at five depths — 0–1 cm, 1–3 cm, 3–9 cm, 9–27 cm and 27–81 cm — and soil temperature at 18 cm. Surface moisture tells you whether a seed will germinate; moisture at 27–81 cm tells you what the crop will live on if it does not rain for a fortnight. Most decisions a farmer regrets were made with only the first number.
It carries vapour pressure deficit and wet-bulb temperature, which are the two figures that decide whether a hot day is merely uncomfortable or actually dangerous to a crop and to the people working in it. A high VPD means the atmosphere is pulling moisture out of every open stomate; a high wet-bulb means sweat stops working. Neither is visible in a temperature reading.
It carries evapotranspiration and growing degree days on a base of 10°C, which together answer how much water the crop actually used and how far through its thermal life it has travelled — the honest version of "how old is this crop", which a calendar cannot tell you because a cold fortnight and a warm one are not the same two weeks.
For anyone working with light, it carries global horizontal irradiance, direct normal irradiance, diffuse radiation and an estimated photosynthetic photon flux, alongside sunlight illuminance. That is the difference between knowing it was sunny and knowing how much energy actually reached the canopy.
It also carries the ordinary things, done properly: relative humidity, mean-sea-level and surface pressure, precipitation, showers and snowfall, rain probability, and wind for spraying decisions.
The seven-day outlook is written as a field-planning summary rather than a row of icons — what the week allows and what it rules out. Where a threshold is crossed it says so; where nothing is close to a threshold it says that too, rather than inventing an alert to look useful.
Every report can be exported as a PDF that carries its own provenance: where each figure came from and how it should and should not be used. A number in a farm report that nobody can trace is a number nobody should act on, and an agronomist or a bank will ask.
It works anywhere in the world, from a chosen location or the device's own, and it does not require a farm profile to be filled in first.
How to use Weather
What it is. A farm weather screen rather than a city one: alongside temperature, rain and wind it carries the agricultural parameters — vapour pressure deficit, wet-bulb temperature, dew point, evapotranspiration, solar radiation, soil profile, freezing level, UV index — and turns the ones that cross a threshold into a plain decision summary.
When to open it. The night before anything that cannot be undone: a spray, a harvest, a sowing, an irrigation. And every morning in the week before harvest.
Have ready.
Nothing but the location. Use 'My location', or choose one — the field's, not the town's, if they are far apart.
Step by step.
Set the location and let it load.
Read the decision summary first. It is the short list of thresholds that have actually been crossed, and on a normal day it says so.
Read the seven-day field-planning outlook for the days you have a decision to make.
Open the detailed parameters when you need the reason behind the advice — the VPD figure behind 'inspect root-zone moisture', for instance.
Export the report if somebody else needs it: a sprayer operator, a contractor, an insurer.
What it will not do. It is modelled weather, not measurement. There is no sensor in your field, the soil profile is modelled, and the radiation-derived figures are conversions. It is not a substitute for an official warning from your meteorological service, and it says so on the screen.
Every setting in Weather, explained
Location
The point the whole forecast is computed for. How to choose: The field. Ten kilometres and two hundred metres of elevation are enough to change a frost call. If it is wrong: Everything on the screen describes somewhere else, confidently.
Vapour pressure deficit (VPD, kPa)
How thirsty the air is — the gap between the moisture the air holds and the moisture it could hold. It drives how fast a crop loses water, far better than temperature alone. How to choose: Read it, do not set it. At 1.6 kPa and above the screen flags strong crop water demand and tells you to check root-zone moisture; below 0.4 it warns that the canopy will stay wet, which is disease weather. If it is wrong: Nothing to get wrong, but ignoring it is the commonest way a crop is under-watered on a day that did not feel hot.
Wet-bulb temperature (°C)
The lowest temperature achievable by evaporation — what a wet thermometer reads in moving air. How to choose: It is the honest measure of heat danger to people working in the field, because at high humidity sweat stops working. It also governs whether evaporative cooling will do anything. If it is wrong: Judging a day's safety by air temperature alone. 38°C at low humidity and 34°C at high humidity are not the same day for the person carrying the sprayer.
Wind speed and gust (km/h)
Sustained wind and the peak gusts. How to choose: For spraying, the gust matters more than the average. At 18 km/h sustained the screen warns about drift; at 40 km/h gusts it raises a proper alert. If it is wrong: Spraying on the average when the gusts are twice it is how a neighbour's crop gets your herbicide.
UV index
The strength of ultraviolet radiation at the surface. How to choose: At 8 and above the screen warns to protect field workers and avoid prolonged midday exposure. If it is wrong: It is about the people, not the crop, and it is the parameter most often ignored on exactly the days it matters.
Evapotranspiration and solar radiation (GHI)
How much water is leaving the field, and how much energy is arriving. How to choose: Use these with the Irrigation Scheduler, which turns the same underlying figures into litres for your field and crop. If it is wrong: Nothing, but reading ET here and irrigating by habit anyway wastes the one number that would have changed the decision.
Dew point and relative humidity
When the air will reach saturation, and how close it is now. How to choose: Dew point near the overnight minimum means a long leaf-wetness period, which is what most fungal infections need. If it is wrong: Reading humidity alone. 80% humidity at 15°C and at 35°C are very different amounts of water.
A worked example
You are deciding whether to spray tomorrow morning.
What goes in:
Location set to the field
Tomorrow: 36°C, gusts to 44 km/h, VPD 2.1 kPa, UV index 9, no rain
What comes out:
Alert: strong wind gust risk for spraying, staking and exposed structures — 44 km/h is above the 40 km/h threshold.
Decision summary: high VPD indicates strong crop water demand; inspect root-zone moisture. Very high UV: protect field workers.
No precipitation alert, so rain is not the reason to wait.
Three separate reasons not to spray tomorrow morning, none of which is visible on an ordinary weather app: the gusts will carry it, the VPD will evaporate it before it lands, and the UV is a problem for whoever is holding the lance.
How to read what it gives you
The decision summary is threshold-driven and deliberately quiet. It says 'no immediate threshold alert is visible' on an ordinary day rather than inventing advice, because a screen that always has something urgent to say stops being read.
The alerts that fire are: gusts at or above 40 km/h, temperature at or above 38°C, temperature at or below 2°C, precipitation at or above 10 mm in the period, and atmospheric instability (CAPE) at or above 1500.
Condition wording and location come from OpenWeather; the agricultural parameters come from Open-Meteo's best-match global models. Sunlight lux and photosynthetic photon flux are conversions from modelled shortwave radiation, not readings from a sensor in your field.
It is a model, everywhere on Earth, and the screen says so. For a spray, frost or safety decision, check it against what you can see and against official warnings.
What usually goes wrong
Using the nearest town instead of the field. Elevation and distance from water change frost and wind more than people expect.
Reading only temperature and rain, which is what every other weather app gives you, and ignoring the four or five parameters that are actually about farming.
Treating a modelled soil profile as a soil moisture sensor. It is a model output and it does not know your irrigation.
Making an irreversible decision on a seven-day-out forecast. Re-check it at two days.
Questions people ask about Weather
What is vapour pressure deficit and why does it matter more than humidity?
VPD is the gap between how much moisture the air holds and how much it could hold at that temperature — how thirsty the air is. It drives how fast water leaves the crop. Humidity alone cannot tell you that, because 80% humidity on a cold morning and a hot afternoon are completely different amounts of water. Above about 1.6 kPa the crop is under real water demand; below 0.4 the canopy stays wet and disease pressure rises.
What wind speed is too windy to spray?
The screen warns about drift at 18 km/h sustained and raises an alert at gusts of 40 km/h or more. Most spray labels specify a range rather than a maximum, because very still air causes its own problem — inversion, where the droplets hang and then move somewhere unexpected. The gust figure matters more than the average.
What does wet-bulb temperature tell me?
It is the lowest temperature evaporation can reach in that air, so it is the honest measure of heat danger to people. At high humidity, sweat stops cooling and a 34°C day can be more dangerous than a dry 38°C one. It also tells you whether evaporative cooling will help in a shed or a store.
How many days ahead does it forecast?
The field-planning outlook runs seven days. The Irrigation Scheduler, which uses the same underlying data, will plan up to sixteen — the longest live daily forecast anyone produces.
Where does the data come from?
Location and condition wording from OpenWeather; the agricultural parameters from Open-Meteo's best-match global forecast models. It works anywhere on Earth. Sunlight lux and photosynthetic photon flux are conversions from modelled shortwave radiation rather than sensor readings, and the screen states that alongside them.
Is Laisha's weather free?
Weather is part of the app. The free tier covers the calculators and the basic screens; the paid subscription covers the intelligence tools built on top, including the irrigation schedule and the exportable reports.
Want to use Weather for real, right now? Open Weather in the Laisha app → Ten days free, no card. After that 10 US dollars a month, one price worldwide.