Rain
Forecast rain and shower probability raise the score because wet surfaces make movement easier.
Weather-aware growing guide
Know when slugs are likely to move.
SowNext turns tonight’s moisture, humidity, temperature, rain and wind forecast into a simple prompt to check vulnerable crops—not a promise that damage will or will not happen.
See how the score works ↓The useful distinction
Activity risk is not the same as pest pressure.
Weather can tell us whether the surface is likely to be comfortable for slug movement. It cannot see the slug population in your plot, recent irrigation, dense foliage, boards, pots or the many damp refuges that create a different microclimate at soil level.
Use the panel as a prompt: a high score means “inspect tonight”; a low score means “weather is less favourable”, not “your seedlings are safe”.
Inside the predictor
Five signals from the coming night.
Humidity
Humid night air slows moisture loss. The score responds most strongly as average overnight humidity approaches saturation.
Surface-soil moisture
Open-Meteo’s modelled 0–1 cm soil moisture is used as supporting evidence. Soil type and irrigation can make your bed wetter or drier.
Temperature
Mild conditions receive more weight. Cold or unusually hot conditions reduce the likelihood of sustained surface activity.
Wind
Light winds add risk; stronger wind encourages drying on exposed soil and foliage.
0–34Low
35–59Watch
60–79High
80–100Very high
The score is a transparent SowNext planning heuristic, not a validated biological model or pesticide decision tool. Forecast data is supplied by Open-Meteo and normally cached in your browser for 15 minutes. Town searches use Open-Meteo geocoding; UK postcode coordinates come from Postcodes.io.
When risk is high
Protect the plants that cannot shrug off damage.
- 1
Start with seedlings
Newly planted lettuce, brassicas, beans and other tender transplants deserve attention before established plants.
- 2
Inspect after dusk
Use a torch on mild, damp evenings. Check the undersides of pots, boards, bed edges and dense leaves, then hand-pick where practical.
- 3
Water in the morning
Plants still receive water, while the soil surface has more time to dry before nocturnal activity begins.
- 4
Reduce accidental refuges
Move unused pots and persistent debris near vulnerable crops, while retaining purposeful wildlife habitat elsewhere in the garden.
- 5
Use biological control selectively
Slug nematodes need moist soil and suitable temperatures. Follow the product instructions and remember they affect non-pest slug species too.
Common questions
Read the score sensibly.
Why is my garden busy with slugs on a low-risk night?
You may have watered, have dense ground cover or damp refuges, or simply have high local numbers. The forecast describes open-air conditions, not every bed-level microclimate.
Does a high score mean crops will be damaged?
No. It suggests weather supports surface movement. Damage also depends on species, population, crop susceptibility and available alternative food.
Why use modelled soil moisture?
It adds useful context beyond rainfall alone, especially after previous wet weather. It is not a measurement from your bed, so the score deliberately treats it as one signal rather than proof.
Sources and further reading
Evidence behind the guidance.
RHS: slugs and snailsEcology, cultural controls and practical management ↗AHDB: research on slug behaviourSoil moisture, temperature, humidity and wind ↗Open-Meteo forecast documentationHourly weather and modelled soil-moisture fields ↗Postcodes.io lookup documentationUK postcode-to-coordinate lookup ↗