Thiruvananthapuram: Forty people, including two children, sustained sunburn on Tuesday as heat continues to rise across Kerala as summer takes hold. There could be an increase of 3 degrees today and tomorrow except in Wayanad and Idukki, the weather department has warned. Meanwhile, ultraviolet rays from the sun have crossed the very dangerous level of 11 to reach 12 units. As good news, summer rains are predicted for the weekend.

Several sunburn cases were reported from Kollam (9), Alappuzha (8), Ernakulam (7), Kozhikode (6), Kottayam (5) and Palakkad (5) districts.

Keep away from direct sunlight between 11am and 3pm, the state disaster management authority advised.

Palakkad continued to register the highest temperature – 41 degrees Celsius Tuesday -- in the state. Thrissur was 39.1 as against 40.4 on Monday. Pathanamthitta also saw temperatures above 40. Average temperature rose 4 degrees in Kottayam to touch 38.5 on Tuesday. Kozhikode saw 36 with a 3 degree hike. Other districts saw an average increase of 2 degrees Celsius.

Heat index

Though temperatures hover below 40 in most districts, heat index across state is above 48 degrees Celsius, said the weather department. Districts from Kochi to Kozhikode will see this rise to 52 today. Heat index above 45 is considered dangerous. Anything above 54 is sure to cause sunburn.

Tuesday temperatures (in degrees Celsius)

Thiruvananthapuram: 35, Kollam (Punalur): 39.5, Alappuzha: 35.4, Kochi: 36.1, Kottayam: 38.5

Thrissur (Vellanikkara): 39.1, Palakkad: 41, Kozhikode: 36, Kannur: 35.4

UV index

UV index is the measure of ultraviolet rays. Their range and effect:

Above 11: Very dangerous. Sunburn in 10 minutes

Between 8-10: Dangerous. Exposure to sunlight for 15-25 minutes causes sunburn.

Between 6-7: High. Sunburn from 30 minute exposure.

Between 3-5: Moderate. Sunburn possible after 45 minutes.