SurfaceCast: Surface TempSurfaceCast: Surface Temp
See how hot the ground actually gets — hour by hour, before you set foot outside.
Download on the App Store
Screenshots
Features
Compare surfaces side by side
Put up to five surfaces on one chart: tarmac, concrete, grass, bare soil, sand, timber decking, brick, painted metal, and light or dark walls. The gap between them is usually far wider than people expect.
Colour changes everything
Keep the material, the orientation and the tilt identical, and change only the colour. On a clear summer day a white surface and a black one can sit around nineteen or twenty degrees apart. SurfaceCast shows exactly how much sunlight each shade absorbs.
Walls and roofs, not just the ground
Every surface carries a compass direction and a tilt, from flat ground at 0° to a vertical wall at 90°. Point a wall east and it warms through the morning; point it west and it peaks late in the afternoon.
Shade that behaves like real shade
Mark the hours when a surface falls into shadow. Sunlight drops to zero at once, but a heavy surface keeps releasing the heat it has stored and cools gradually — the lag you feel outdoors, modelled properly.
Read any hour in detail
Tap an hour for a table showing each surface's estimated temperature, the difference from air temperature, the sunlight landing on that face, its shade level, and how confident the estimate is.
Save the places you check often
Store a set of surfaces under a name like “the back garden” or “the dog walk”, then reload it later with a new date. Works from a cached forecast when you are offline, in Celsius or Fahrenheit.
Air temperature tells you almost nothing about how hot the ground actually is. On a sunny summer afternoon, dark tarmac can run far above the air, while the grass a step away stays close to it. SurfaceCast draws that difference as a curve, hour by hour, before you set foot outside.
Pick a place and a date. From the real hourly forecast for that spot, the app estimates how a surface warms up and how it cools down across the day.
COMPARE MATERIALS
Dark tarmac, light concrete, dark concrete, grass, dry soil, damp soil, dry sand, timber decking, brick, light or dark painted metal, a white wall and a dark wall. Up to five scenarios drawn on one chart, so the gaps are obvious at a glance.
CHANGE NOTHING BUT THE COLOUR
This is the experiment that surprises people most. Keep the same material, the same orientation, the same tilt, and shift the colour from white to black. At the height of summer the gap can reach nineteen or twenty degrees. Handy when you are choosing a roof colour, a render, a shade of decking oil or the paving for a courtyard.
WALLS AND ROOFS, NOT JUST THE GROUND
Every surface carries a compass direction and a tilt, from 0° flat to 90° vertical. An east-facing wall warms through the morning; a west-facing one peaks late in the afternoon. Four one-tap presets cover the north, east, south and west walls.
SHADE THAT BEHAVES LIKE REAL SHADE
Mark the hours when a surface falls into shadow, say from 11:00 onwards. Sunlight drops to zero at once, but the temperature does not: heavy materials release their stored heat slowly and cool gradually. That lag is the whole point, and SurfaceCast models it rather than switching the curve off.
WHAT YOU GET
• A 24-hour estimated surface temperature curve for up to five scenarios
• Hourly weather for your location, or anywhere you search for
• Air temperature overlaid as a dashed line, so the gap is easy to read
• Sunrise, solar noon and sunset markers, plus shaded bands on the chart
• Tap any hour for a side-by-side table: temperature, difference from the air, sunlight landing on that face, shade level and an estimate confidence
• Peak temperature and the time it occurs, for every scenario
SAVE YOUR SETS
Store a place and its surfaces under a name of your own — "the back garden", "the dog walk", "the neighbouring roof" — then reload the lot on another date.
WHO IT IS FOR
Judging the pavement before the dog goes out, children playing in the garden, gardening and balcony pots, DIY before you commit to a colour, students and practitioners in architecture, landscaping and groundworks, photographers scouting locations, camping, and anyone curious about urban heat.
HOW IT WORKS
SurfaceCast computes the sun's position for your place and time, works out how much sunlight reaches a face at that tilt and direction, then runs a heat balance in short internal steps: sunlight absorbed, heat carried away by the wind, heat radiated to the sky, heat exchanged with the ground below, and evaporative cooling on damp surfaces. Every material brings its own absorptivity, emissivity and thermal mass, so heavy and light surfaces behave differently, as they should. The previous 24 hours run first as a warm-up, so the starting value does not distort the day you are looking at.
ALSO
Celsius or Fahrenheit, works offline from the last saved forecast, no further purchases. iPhone and iPad.
PLEASE NOTE
Every figure is a physics-based estimate, meant for observation, learning and curiosity. Real surfaces vary with thickness, construction, moisture, reflections from nearby buildings, local wind and the exact shape of the shadow. SurfaceCast is not a measuring instrument and does not judge whether a surface is safe to touch or walk on. When that matters, measure it with an infrared thermometer.