Weather decisions for outdoor work
Prelay watches the conditions that decide whether a job can happen — rain, wind, heat, cold, ice, and how wet the ground is — at every site you work. It grades each coming day for the work you do there and puts the grade, the reasons, and every change in front of your people and your systems — so the call is yours, made with the facts, before the trucks roll.
Rain, wind, and a wet site at once
The problem
Nobody budgets for a rainout. It still gets paid for — in payroll, fuel, idle iron, wasted material, and the job that now starts a day late. A forecast is information. The dispatch decision is where the money moves.
You already know your number. Prelay exists so you can see, the night before, whether the day is likely to hold — and decide accordingly.
What changes
01
See whether the window is actually there before the trucks roll. Every site’s coming days are graded for the work scheduled there, so the go/no-go call can be made the night before, with the reasons in front of you — not in the parking lot.
Per-activity, per-day grades with reasons · optional notice before a Poor or Unsafe day
02
Concrete, asphalt, coatings, sealants, and roofing systems each have conditions they will not forgive. See, for each coming day, whether the temperature floor, rain chance, ice, and ground wetness are on your side before material is committed.
Temperature floors and ceilings · frozen precipitation · estimated ground wetness
03
Set the gust, wind, ice, and temperature limits your team already works to. Supervisors see the days that cross them ahead of time — information for the people who make the safety call, alongside your safety program and never a substitute for it.
Ensemble gust probabilities · your thresholds, within guardrails
04
Rain ends and the car wash fills. A heat streak forms and the tune-up calls start. Get the signal the moment the pattern your business waits for shows up, and let it start the promotion, staffing call, or outreach you planned in advance.
Prelays fire once, on the rising edge · email + signed webhook
Work suitability
Tell Prelay which trades you work in. For each site it grades the days ahead per activity — a shingle install, a concrete pour, a mowing route, pole work — morning and afternoon, and says exactly which limit was reached. When a data source is missing it says Limited data, never “fine.”
| Activity | Thu | Fri | Sat | Mon | Tue |
|---|---|---|---|---|---|
| Roof installation | Poor | Good | Good | Marg. | Unsafe |
| Concrete placement | Poor | Marg. | Good | Good | Poor |
| Mowing and trimming | Poor | Poor | Marg. | Good | Limited |
Thu · Roof installationPoor
Baseline tolerances · catalog v0.5 · every grade carries its provenance
LWNN sets the baseline for each activity. You tune the gust threshold for your equipment, how much risk you accept before a day reads Marginal, Poor, or Unsafe, and your working hours. The Unsafe band can be moved, never switched off, and every change is audited.
Grades are estimates calculated by LWNN from forecast and modeled or observed weather data. They are decision support, not a safety determination, and are not on-site measurements. Wind and rain grades are probabilities derived from a weather-model ensemble.
Who makes these calls
Contractors carry the sharpest version of the problem — a wrong call costs a crew day. But the same engine serves any business whose revenue moves with the sky.
The crew, the trucks, and the drive are paid for whether or not the work happens. See the go/no-go picture the night before, not in the parking lot.
Commit the crew to a window that will hold.
Tear off Thursday, or wait for Friday?
Grades each coming day for tear-offs, installs, repairs, and gutter work on rain chance, gust probability, ice, and heat — and can notify you the evening before a day grades Poor or Unsafe.
Stop paying crews to discover mud.
Send the mowing crew to the saturated property, or re-route to the dry one?
Estimates ground wetness at every property and grades mowing, planting, irrigation, and applications per day. A wet-ground prelay can flag a site as too wet for equipment before dispatch.
Know whether the ground will carry an excavator before it is on the trailer.
Start grading Monday, or give the site two more days to drain?
Tracks observed rainfall and estimated soil wetness per site, and fires the moment the ground has dried enough to work.
Concrete, asphalt, coatings, and roofing systems all have conditions they will not forgive. Commit material when the window holds.
Order the trucks for a pour that can cure.
Place Wednesday’s slab, or push the ready-mix order?
Checks the temperature floor, rain chance, frozen precipitation, and ground wetness for placement, flatwork, brick and block, and mortar work across the coming days.
Lay asphalt when the mat can hold temperature.
Pave and sealcoat this week, or hold the crew?
Grades paving, sealcoating, crack filling, striping, and repairs on daily highs, rain chance, and frozen precipitation.
Coatings do not forgive a cold night or a wet afternoon.
Spray today, or lose the finish to tonight’s low?
Grades exterior painting, staining, caulking, and pressure washing on daily lows, rain chance, and wind, so application days are scheduled where they will hold.
Set the gust, wind, ice, and temperature limits your team already works to. See the days that cross them before the crew is scheduled.
See the gust risk before anyone is aloft.
Put the climber up today, or reschedule the removal?
Grades trimming, removal, and cabling on the probability that gusts exceed your limit during the work window — from every member of an ensemble forecast, not one number.
Pole work and trenching answer to different weather.
Is tomorrow a bucket-truck day or a trench day?
Grades pole and aerial work on gust probability and ice, and trenching on ground wetness and rain — so dispatch can swap crews between them.
Rooftop racking and a 35-mph gust do not mix.
Rooftop install tomorrow, or move the crew to the ground-mount?
Grades rooftop, racking, and ground-mount solar plus crane-assisted generator lifts and service work on gusts, rain, ice, and heat — and puts the grade and its reasons in front of supervisors before the day is scheduled.
Some businesses fill up when the weather turns. Get the signal the moment the pattern shows up, and let it start the campaign, staffing call, or outreach you planned.
Fill the bays the day the roads dry.
When does the win-back promo go out?
After a rainy stretch, when the forecast clears to several straight dry days, Prelay fires — once, at the right moment — and your campaign goes out.
Tee sheets fill when the fairways dry.
Staff up and push the weekend, or not?
Fires when a wet stretch ends and dry, warm days are ahead, so the pro shop, the grounds crew, and the marketing land together.
Be first in the inbox when the heat wave forms.
Launch the tune-up push now, or wait and see?
Fires when a streak of days above your heat threshold shows up in the forecast — and grades rooftop and crane-assisted installs for your own crews.
Book winter installs before the first flake.
When does the winter-tire campaign ship?
Fires a set number of days before the first forecast snowfall, tolerant of forecast jitter so it does not fire twice.
Stage the rain plan before ticket-holders ask.
Do we cover the lawn seating this weekend?
Fires when rain chance crosses your threshold on any day inside your booking window.
Protect the trees before the first frost.
Run frost protection tonight?
Fires days ahead of the season’s first forecast night below your frost line.
Decisions we are building the weather data for next — tell us if one is yours:
Mobilize before the first plow-truck competitor wakes up.
Stage salt and crews tonight?
Forecast snowfall amounts are not in the engine yet. If this is your business, tell us and we will prioritise it.
The economics
Prelay is a flat monthly subscription, priced by how many sites you monitor. Put a month of it next to any one of these. If the information helps you avoid a single one in a season, the math is done — and most crews see more than one a season.
Talk to us about your sitesHow it connects
01
Search an address. Prelay starts recording observations there around the clock and building the site’s history from day one.
02
Pick the trades you work in for day-by-day grades. Arm prelays — rules that fire once, the moment a condition flips true — for the calls you make on repeat.
03
Grades, reasons, and changes reach your people by email, your dispatch, scheduling, or CRM systems by signed webhook, and your whole team in the portal. Every delivery is logged.
Conditions are false, false, false — then true. That edge is when a prelay fires: no repeat alerts while the condition stays true, no double-fire when a forecast wobbles, and a re-fire only when a Poor day escalates to Unsafe. Start from a template, set the knobs to your operation, and decide what your side does with the signal.
Where it lands
For your developers
Every fire is an HTTPS POST to your endpoint, signed with a per-rule secret — HMAC-SHA256 over the exact body in the X-LWNN-Signature header — so your side can verify it came from us and nothing in between touched it.
idempotency_key. suitability block: each breached activity/day with its grade, reasons, wind probabilities, morning/afternoon segment grades, and provenance.X-LWNN-Event: weather.trigger.fired
X-LWNN-Signature: sha256=7f3a91c4…{
"event": "weather.trigger.fired",
"trigger": { "id": 42, "name": "Rain-then-shine win-back" },
"location": { "id": 118, "label": "Sudsy's #12 — Dublin OH" },
"condition_summary": "rained 3 of last 3 days AND 3 straight dry days ahead",
"matched": [
{ "check": "Rained 3 of the last 3 days", "observed": "3/3 days with measurable rain" },
{ "check": "3 straight dry days ahead", "observed": "Thu–Sat clear, precip < 25%" }
],
"fired_at": "2026-08-27T12:15:04Z",
"idempotency_key": "a3f18c2e90b44d5f"
}Prelay is onboarding early customers now — roofers, landscapers, concrete and paving crews, tree services, car washes, golf courses. If weather decides whether your crews make money on a given day, tell us about the call you make.