| Length | Width | Cell | Temp | RH | Sun | Shade | Moist | Wind | Hotspots |
|---|---|---|---|---|---|---|---|---|---|
| 10 | 6 | 1 | 30°C | 55% | 8 | 20% | 40% | 6 km/h | 1 |
| 16 | 8 | 1 | 34°C | 45% | 10 | 15% | 35% | 8 km/h | 2 |
| 24 | 12 | 2 | 86°F | 60% | 9 | 30% | 50% | 5 mph | 0 |
This tool first estimates base heat index (HI) from air temperature and relative humidity. HI is computed using the Rothfusz regression in Fahrenheit units, with common humidity adjustments.
− (0.10 × Wind_mph) + HeatIsland + (GradientStrength × Gradient)
+ HotspotInfluence − (0.8 × BorderCooling × EdgeBoost)
- Pick units, then set length and width for your garden area.
- Choose grid mode: cell size or fixed rows and columns.
- Enter temperature and humidity to estimate base heat index.
- Add sun, shade, moisture, wind, and heat island effects.
- Optionally define hotspots to match reflective or paved zones.
- Press calculate, then review map, summary, and guidance.
- Download CSV for analysis or PDF for quick sharing.
Microclimate mapping for productive beds
This grid translates weather and site inputs into a cell-by-cell stress view. Use it to compare beds, paths, and borders where heat accumulates. A higher score indicates stronger combined exposure from humidity, sun, and local surfaces.
Heat index as a plant stress baseline
The calculator estimates heat index from temperature and humidity, then uses it as the baseline for every cell. Heat index aligns well with leaf water loss risk during hot, humid periods. When humidity drops, airflow and shade usually become more effective.
Sun, shade, moisture, and wind adjustments
Sun hours raise the score because radiation increases canopy temperature. Shade percentage reduces the score by lowering incoming energy. Soil moisture reduces the score by supporting evaporative cooling at the root zone. Wind lowers the score by improving convective cooling and drying.
Hotspots and gradients for real garden features
Hotspots model localized heat sources such as dark paving, reflective walls, metal fences, or brick edges. Gradients help represent slopes, afternoon exposure, or sheltered corners. Use modest values first, then calibrate by comparing the map to midday observations.
Planning actions from the finished heat map
Group crops by zones: fruiting plants tolerate warmer cells, while greens prefer cooler pockets. In hot cells, add mulch depth, drip scheduling, and temporary shade. In cool cells, watch for slower drying and reduce irrigation frequency to prevent root stress. Record readings for one week to refine inputs. Note irrigation timing, then rerun after adjustments. Recalculate after pruning, mulching, or adding shade. Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field notes weekly Update inputs using simple field.
What does each colored cell represent?
Each cell shows a relative heat stress score for that location. Colors are assigned by ranking values between the grid minimum and maximum into five bands, helping you spot cooler pockets and persistent hotspots.
Is the score a real temperature reading?
No. It is a combined index based on heat index plus site modifiers like sun, shade, moisture, wind, and hotspots. Use it for comparison within the same run and to track improvements after changes.
How should I choose grid size?
Use smaller cells for detailed beds and container areas, and larger cells for big plots. Keep the grid under the built-in limit to maintain fast loading and clear visualization.
When should I use hotspots?
Add hotspots to model heat from paving, walls, reflective surfaces, or dark mulch. Place hotspot coordinates where the heat source sits, then increase intensity gradually until the map matches what you observe.
Why do edges sometimes appear cooler?
Border cooling reduces scores near edges to reflect airflow and exposure. If your borders are actually hotter due to hardscape, lower border cooling and add a hotspot near that edge instead.
How often should I recalculate?
Recalculate whenever weather patterns shift, irrigation schedules change, or you modify shade, mulch, or structures. Many gardeners update weekly during heat waves and after any major garden layout changes.