How it works
From job to verdict, with the working shown
CropWindow is a matching engine, not a weather app with opinions. Your job's limits, checked against every hour of the local forecast, scored for confidence, and explained. This page opens the black box — every stage, real numbers.
Step 1 — pick the job
Every job carries its own weather rules
Twenty templates, from boom spraying to fencing. Each one is a set of thresholds — the numbers an experienced operator already carries in their head, written down. Every number is editable, because your rig and your risk tolerance aren't ours.
Boom spray — herbicide
- Wind 4–20 km/h — drift above, inversion risk below (20 assumes a drift-reducing setup — the guides teach 3–15 as the everyday band)
- Delta T 2–10, flagged when outside the GRDC ideal 2–8
- Rainfast 6 dry hours after the pass
- Start after dew burn-off; inversion check on
Cut hay
- Dry run 4 consecutive dry days, cutting to baling (set 3–5)
- Rain tolerance once cut 0 mm — rain on a windrow is ruinous
- Cure low humidity favoured for faster drying
Spread urea
- Rain wanted ~10 mm within 72 hours to wash the nitrogen in — sooner is better: the guide's 48-hour rule is the conservative read, and the far end of that window scores lower confidence
- Rain feared falls over 25 mm — runoff, not incorporation
- Wind under 20 km/h for an even spread pattern
Those are the shipped defaults, drawn from published GRDC and BoM guidance. In the app they're a starting point, not a ruling.
Step 2 — the match
Every forecast hour, scored against every threshold
The engine walks the hour-by-hour forecast for your pin — wind, temperature, humidity, rain — and computes Delta T for each hour along the way. Each hour either passes all of a job's thresholds or it doesn't. Passing hours get stitched into windows: six dry hours in a row for a herbicide pass, four clear days end to end for hay.
Then each window gets a confidence score, and this is where honesty matters. Confidence drops when the margins are tight — forecast wind of 18 km/h against your 20 max is a pass, but a nervous one. It drops with distance — a window six days out rests on a forecast that will change. And it drops hardest for multi-day jobs, because a hay run needs every single day to hold, not just the first.
Step 3 — the call
Red, amber, green — and what they actually mean
Green is not a promise and red is not never. The colour is a confidence call on the forecast holding — the same judgement you'd make yourself, made explicit.
Good to go
Boom spray — herbicide
Tomorrow · 11am–5pm
Wind 8–14 km/h through the window, Delta T holding 4–7, next rain 2am the following morning. Comfortable margins on every threshold, near horizon. Go — and still glance at the boom-height breeze before you mix.
Cutting it fine
Spread urea
Thursday
About 8 mm forecast for Friday, which would wash it in nicely — but the models don't agree on that rain yet. If it firms up, this goes green. If it fades, spreading now leaves nitrogen gassing off dry ground.
Hold off
Cut hay
This week
Best run on offer is two dry days and you need four. Wednesday's front ends every window that starts before it. Nothing worth dropping a paddock for — wait for the pattern to settle.
The working
Every call carries its reasons
Tap "why" on any recommendation and you get each threshold against what the forecast actually says — no vibes, no summary weather icon. A green herbicide window reads like this:
- Wind — 8–14 km/h across the window, inside your 4–20 band
- Delta T — 4.2 to 6.8, inside the GRDC ideal 2–8
- Rainfast — next rain 2am; you need 6 dry hours after a 5pm finish, and you've got 9
- Inversion — steady overnight breeze forecast, low risk after dew burn-off
The reasons are there so you can disagree with them. If your paddock sits in a frost hollow the model can't see, you'll know — and you can tighten the threshold so the app knows too. Guidance, not gospel; on chemical jobs, the label is the law.
It keeps checking
The forecast moves. So does the answer.
A window found on Monday isn't left standing on Thursday's say-so. CropWindow re-runs the match as each new forecast lands, and if a green window goes bad it withdraws the call and tells you why — before you've hooked up, not after you've mixed.
"Holding off — winds picked up to 22 km/h. Not worth the drift."
A morning-of withdrawal, exactly as the app puts it.
An app that only ever says go isn't a decision tool, it's a cheerleader. The withdrawals are the feature.
The method's open. Point it at your paddocks.
Free in early access, Android now. Your jobs, your thresholds, a straight answer every morning.
Get CropWindow for Android →