Heat Check – NSTL

Heat check — North Somerset Tennis League

North Somerset Tennis League

Heat check

Check the conditions forecast for a fixture before anyone sets off. Uses the LTA Extreme Heat Policy thresholds.

How this works

The forecast temperature and humidity for the postcode at the match hour are used to calculate two figures. Nobody needs to take a reading on court.

Heat Stress Index: Air temperature combined with humidity — the LTA's primary measure. Modification of play at 34.0°C, suspension at 40.1°C.
WBGT (estimated): Wet Bulb Globe Temperature, estimated from the same two figures. Modification at 30.1°C, suspension at 32.2°C. A true WBGT reading also captures sun and wind, so this estimate runs low on a court in full sun.
Wind and sun: Shown for guidance only — neither is used in the calculations above. Wind helps you shed heat; strong sun and still air make conditions on court worse than the figures suggest. Sun is given in watts per square metre, the standard measure of how much solar energy is arriving: under 150 is weak, over 600 is very strong.

Both indices are shade measures. Courts absorb heat all day and radiate it back into the evening, so conditions at ankle and chest height can be hotter than any forecast shows. Treat a figure near a threshold as being over it.

Every check fetches the current forecast, and the underlying weather models are re-run through the day. A figure taken the evening before will not necessarily be the figure two hours before the match. Where a reading is near a threshold, it is worth checking again closer to the time.

Forecast from Open-Meteo, postcode lookup from postcodes.io. Neither the League nor this page can judge an individual player's fitness to play — that stays with the player.