Mow Day

When can I mow the lawn? The next window with room for the whole mow, within the hours you have.

The app

Mow Day on a clear day: the next mowing window, the grass, rain and wind, and a start-by time — One look at when a mow might fit.

The Mowing days page: today and the next two days, each a patch of its own field, with the best day tagged — Today, or one of the next two days?

How this is worked out: the forecast hour, the FAO-56 Penman–Monteith working and the water estimated on the blades — The working behind every verdict.

A morning after rain: the grass likely damp, with an estimate of when it should dry off — Honest when the grass may still be wet.

A short window with rain forecast close behind and an aim-to-start time — Only just enough time — rain may follow.

A rained-out day: not today, the reason, and the next chance tomorrow — Some days it just says: not today.

What you get

A verdict in plain words — great time to mow, good time to mow, grass likely damp, rain close behind, or better to wait — with the reason in one sentence.
The next estimated mowing window, sized to the mow you actually do: tell it how long a mow takes and which hours you are free, and it stops offering gaps you cannot use.
An estimated start-by time, and what closes the door: rain, the light going, or the end of the hours you set.
Whether the grass has had a chance to dry off — after rain, and after a heavy dew — with an estimate of when it should.
The next three days as mowing advice, with the best day tagged.
Quiet, optional alerts: a heads-up the evening before a good mowing day, and a nudge when the window opens. Nothing else, ever.
Two things about your lawn that change the answer: shade, and ground that stays soft.
The working behind every verdict, one tap away.

Worked out, and shown

Mow Day combines the published FAO-56 Penman–Monteith reference evapotranspiration calculation — the UN Food and Agriculture Organization's method for a clipped grass surface — with its own assumptions about water on the grass and in the topsoil. Each forecast hour's temperature, dew point, wind and solar radiation go into it, to estimate how quickly wet blades may dry, and a separate topsoil water balance estimates whether the ground is likely still soft.

Tap "How this is worked out" under any verdict and the app shows its working: the forecast for that hour, the equation with its numbers, and the water estimated on the blades and in the topsoil — every figure labelled as an estimate from a forecast.

Honest about forecasts

A forecast is a guess, and Mow Day says so. It cannot see your lawn — not how long the grass is, not how soft the ground is underfoot, and not exactly what fell on it before the forecast began. When it cannot see far enough back, it tells you that too. The last look at the grass stays with you.

Quietly respectful

No accounts, no tracking, no lawn diary. Your location is used to fetch the forecast and to name your town — we run no servers and collect nothing.

Free, and ad-free for now. If you’d like to say thanks, Settings offers three small one-time purchases — and any one of them keeps the app free of ads for good, whenever a single unobtrusive banner returns. No subscriptions, ever.

Contact

Questions, feedback, or support: support@ostapenko.studio

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