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Annex A - Wet Bulb Globe Temperature (WBGT) from Temperature and Relative Humidity

When a WBGT monitoring device is unavailable, the chart below can be used to estimate WBGT. It must be noted that these are estimates and are derived only from using temperature and relative humidity. The chart accounts for full sunshine and light wind conditions. Thus, depending on the radiant heat load from the sun and the wind, the actual WBGT reading could be different from what is on the chart.

Wet Bulb Globe Temperature (WBGT) from Temperature and Relative Humidity
    Temperature (°C)
    20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
Relative Humidity (%) 0 15 16 16 17 18 18 19 19 20 20 21 22 22 23 23 24 24 25 25 26 27 27 28 28 29 29 30 31 31 32 32
5 16 16 17 18 18 19 19 20 21 21 22 22 23 24 24 25 26 26 27 27 28 29 29 30 31 31 32 33 33 34 35
10 16 17 17 18 19 19 20 21 21 22 23 23 24 25 25 26 27 27 28 29 30 30 31 32 32 33 34 35 36 36 37
15 17 17 18 19 19 20 21 21 22 23 23 24 25 26 26 27 28 29 29 30 31 32 33 33 34 35 36 37 38 39 WBGT > 40
20 17 18 18 19 20 21 21 22 23 24 24 25 26 27 27 28 29 30 31 32 32 33 34 35 36 37 38 39 WBGT > 40 WBGT > 40 WBGT > 40
25 18 18 19 20 20 21 22 23 24 24 25 26 27 28 28 29 30 31 32 33 34 35 36 37 38 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
30 18 19 20 20 21 22 23 23 24 25 26 27 28 29 29 30 31 32 33 34 35 36 37 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
35 18 19 20 21 22 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
40 19 20 21 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
45 19 20 21 22 23 24 25 26 27 27 28 29 30 32 33 34 35 36 37 38 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
50 20 21 22 23 23 24 25 26 27 28 29 30 31 33 34 35 36 37 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
55 20 21 22 23 24 25 26 27 28 29 30 31 32 34 35 36 37 38 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
60 21 22 23 24 25 26 27 28 29 30 31 32 33 35 36 37 38 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
65 21 22 23 24 25 26 27 28 29 31 32 33 34 36 37 38 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
70 22 23 24 25 26 27 28 29 30 31 33 34 35 36 38 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
75 22 23 24 25 26 27 29 30 31 32 33 35 36 37 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
80 23 24 25 26 27 28 29 30 32 33 34 36 37 38 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
85 23 24 25 26 28 29 30 31 32 34 35 37 38 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
90 24 25 26 27 28 29 31 32 33 35 36 37 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
95 24 25 26 27 29 30 31 33 34 35 37 38 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40
100 24 26 27 28 29 31 32 33 35 36 38 39 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40 WBGT > 40

Note: This table is compiled from an approximate formula which only depends on temperature and humidity. The formula is valid for full sunshine and a light wind.

Source: Wet Bulb Globe Temperature Monitoring

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