If thunder follows a lightning flash by thirty (30) seconds or less, play must cease and players and officials leave the field immediately.
Play must not resume until thirty (30) minutes after the initial lightning flash. If during the suspension of play thunder follows a lightning flash by thirty (30) seconds or less the suspension period is to recommence.
Note. A 30 second time difference indicates the flash was within a 10km radius, a 15 second time difference is within a 5km radius, and a 3 second difference indicates within a kilometre.