Mushroom Weather | When to Go Looking

The last two weeks

The window that matters, 4 to 12 days ago Rain outside it, in mm per day

The week ahead

Each day the 4 to 12 day window slides forward. The best day is the one where the rain that has already fallen, or lands in the next two days, sits best inside it. The bar shows how good conditions are, not how much it rains.

Your season

Worked out from where you stand.

Latitude and elevation, not a calendar.

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Spring flush Main flush

How we work it out

Fungi keep their own clock.

1. The rain that counts

Fungi fruit days after rain, not the morning after. So we add up the rain that fell 4 to 12 days ago: the coloured band in the chart above. It weighs most in the verdict. Yesterday's rain is not wasted, it simply starts to count a few days from now.

2. The soil, not the sky

Then we read how much water the top 7 cm of ground is holding right now. Under 15% the soil is dry, from 22% it is moist, above 30% very moist.

3. The temperature

Between 8 and 20°C conditions are favourable. Between 4 and 25°C they are borderline. Outside that, even good rain struggles.

4. The season where you are

Before any of this we check the season, from latitude and elevation rather than the calendar. In the mountains autumn fruiting starts earlier, in the south later, and below the equator the year flips. Out of season we give no weather verdict at all.

How the verdict comes out

Rain, soil and temperature each earn points. Worth a look requires at least 4 points and more than 6 mm of rain in the 4-to-12-day window; from 6 points conditions are prime. Otherwise it is too dry. The best day of the week is worked out the same way, day by day.

What this is not

This tells you whether the walk is worth it. It says nothing about what you find, and nothing about what you do with it. It cannot see your soil type, your woods or your slope. Learn your species, and check the rules where you are.

Data, thresholds and sources ↗

Field plate