Different fungi, different weather.

The Shroomify Research Project looks at how weather affects the appearance of mushrooms. In this study, we brought together over a million matched fungal events covering 362 species, along with 14 years of information about rain, soil moisture, soil temperature and air temperature.

We looked at weather over several periods, from the previous few days to the previous two months. This matters because mushrooms respond to conditions that build and change over time. A spell of rain, a gradual cooling of the soil and the amount of water left in the ground can each play a different part.

The clearest finding is that there is no single kind of “mushroom weather”. Each species has its own pattern. The conditions that favour a cep are not the same as those associated with a chanterelle, a morel or chicken of the woods.

Each species follows its own pattern

Weather improved our ability to explain the timing of records for most of the species we studied. The improvement was small for some fungi and much stronger for others. The most useful weather factor also changed from one species to another.

Rainfall and soil moisture, for example, are not interchangeable. Rain tells us that water has fallen. Soil moisture tells us how much water remains after it has drained away or evaporated. Soil temperature describes conditions around the underground fungus, while air temperature describes conditions above it. Looking at these separately reveals patterns that would be hidden by a simple wet or dry rating.

These results show associations in a large collection of real-world records. They do not prove that one weather event caused a mushroom to appear, and they should not be read as exact rules. Their value lies in showing which combinations of weather and timing repeatedly appear alongside records of each species.

Six species in detail

Cep or porcini (Boletus edulis) showed a clear link with cooling soil. The strongest signal appeared about eight to fourteen days before the mushroom was recorded, and a weaker version remained visible into the following week. Recent soil moisture also helped, but rainfall on its own told us much less. For ceps, the changing condition of the ground appears to be more informative than whether it has rained in the past day or two.

Chanterelle (Cantharellus cibarius) followed a broader moisture pattern. Records were more common after recent rain, but rain two to four weeks earlier also mattered. Moisture held in the soil was useful at similar points. The temperature pattern was mixed, with cooler soil close to fruiting but warmer air during the previous week. This suggests that chanterelles respond to a sequence of changing conditions rather than one simple trigger.

Hedgehog fungus (Hydnum repandum) was associated with a longer period of wet weather. Rain and soil moisture from roughly two to eight weeks earlier were more useful than the most recent rainfall. Cooler soil during the final week was also part of the pattern. This is noticeably different from the chanterelle response, even though both are prized woodland fungi and often appear during the same part of autumn.

Parasol (Macrolepiota procera) was one of the species most strongly linked with weather. Rain was useful across every period we tested, with the strongest response about eight to fourteen days before a record. At the same time, records were associated with warmer air and cooler soil during the final fortnight. This contrast between air and ground temperature is a good example of why broad labels such as warm, cold or wet are not enough.

Morel (Morchella esculenta) appeared on the drier side of several comparisons. Records were linked with less rain during the previous two to four weeks and with cooler, drier soil in the final days. However, greater soil moisture two to three weeks earlier was also part of the pattern. This may point to a period of moisture followed by a cooler, drying surface. The morel result is based on fewer records than the autumn species above, so we are treating it with greater caution.

Chicken of the woods (Laetiporus sulphureus) provided a useful contrast because it fruits from wood rather than directly from the soil. Records were associated with warmer soil and drier ground during the final week. Recent rainfall made little difference, although rain much earlier in the season showed a small positive link. A wood-rotting fungus does not necessarily follow the same near-surface moisture pattern as a mushroom emerging from the woodland floor.

Season depends on place

A mushroom season does not begin on the same date everywhere. Latitude affects day length and the amount of warmth built up through the year. Elevation changes temperature, exposure and snow cover. Slope, aspect and tree cover create further local differences.

This is particularly important in places such as the Cairngorms. A high mountain site may be well into its local fruiting season even when a broad national comparison says that the weather is cooler or drier than normal. “Below normal” does not automatically mean worse for mushrooms. Cooler conditions may suit one species, while holding back another.

The current research compares each location with its usual seasonal weather and adjusts the expected fruiting season across broad latitude bands. We are now working on a more detailed treatment of elevation and terrain. Until that local timing is reliable, the map should not turn a general weather difference into a confident claim that mushroom conditions are poor.

Testing against what we already know

Tree and habitat relationships give us an important way to test the work. The data recover well-known links such as chanterelle with pine, winter chanterelle with spruce and orange birch bolete with birch. These are not surprising discoveries. They are checks that the habitat data are behaving sensibly before we place confidence in less familiar weather patterns.

Soil chemistry, soil texture, organic matter, bedrock and terrain help us describe where suitable habitat is likely to exist. Including them also reduces the risk of mistaking a host-tree pattern for a weather response. The interesting question is then what weather can add after the normal season and the character of the habitat have already been considered.

How to read the results

Fungal observations gathered in the field are never as tidy as a controlled experiment. People record more fungi near roads, paths and populated areas. Some species attract far more attention than others. Weather and soil data cover areas of land rather than the exact patch where each mushroom grew.

We have tried to reduce those problems by comparing records with similar places and dates, allowing for changes in recording effort and testing the models on data that were not used to build them. We also repeat the analysis to see whether the direction of each result remains steady. These checks make the findings more useful, but they cannot remove every source of uncertainty.

The results are therefore best read as carefully tested patterns, not fixed rules. They can tell us which conditions have tended to accompany a species. They cannot guarantee that it will be present at a particular place on a particular day.

Bringing the research into Shroomify

Our aim is to give each species a clear account of the weather pattern linked with its fruiting. That will include the balance of rain and soil moisture, the relevant temperature changes, how long the response appears to take and how the pattern changes with season and habitat.

These species accounts will be added to Shroomify as the results are checked and improved. The app will then be able to explain why current conditions may favour one fungus but not another, and allow interested users to explore the evidence in more detail.

This information is intended to help people understand fungal ecology and plan better observations. It cannot identify an individual mushroom or decide whether it is safe to eat.