A method performed by a thermometer apparatus and for providing correct and true alarms for Tipi events for a child covered by a quilt or a blanket, the method comprising: measuring (S21) a skin-surface temperature at a first temperature sensor element of the thermometer apparatus at a measuring rate; measuring (S22) an ambient temperature at a second temperature sensor element of the thermometer apparatus at the measuring rate; calculating (S23), by a central processing unit , a plurality of first change rates (S1) for the skin-surface temperature and a plurality of second change rates (S2) for the ambient temperature over a time interval; calculating (S241), by the central processing unit, a change rate difference between each of the plurality of second change rates and a corresponding one of the plurality of first change rates to obtain a plurality of change rate differences; averaging (S242), by the central processing unit, the plurality of change rate differences to obtain an averaged change rate difference; and comparing (S243), by the central processing unit, the averaged change rate difference with a threshold to determine whether or not to trigger an alarm; and selecting (S251), by the central processing unit , to trigger the alarm in response to the averaged change rate difference being less than the threshold; or selecting (S253), by the central processing unit , not to trigger the alarm in response to the averaged change rate difference being equal to or greater than the threshold; wherein the ambient temperature is a temperature in the quilt or blanket when the quilt or the blanket well covers the child and turns to be a temperature of a sleeping room or a bedroom when the Tipi event takes place. measuring (S21) a skin-surface temperature at a first temperature sensor element of the thermometer apparatus at a measuring rate; measuring (S22) an ambient temperature at a second temperature sensor element of the thermometer apparatus at the measuring rate; calculating (S23), by a central processing unit , a plurality of first change rates (S1) for the skin-surface temperature and a plurality of second change rates (S2) for the ambient temperature over a time interval; calculating (S241), by the central processing unit, a change rate difference between each of the plurality of second change rates and a corresponding one of the plurality of first change rates to obtain a plurality of change rate differences; averaging (S242), by the central processing unit, the plurality of change rate differences to obtain an averaged change rate difference; and comparing (S243), by the central processing unit, the averaged change rate difference with a threshold to determine whether or not to trigger an alarm; and selecting (S251), by the central processing unit , to trigger the alarm in response to the averaged change rate difference being less than the threshold; or selecting (S253), by the central processing unit , not to trigger the alarm in response to the averaged change rate difference being equal to or greater than the threshold; wherein the ambient temperature is a temperature in the quilt or blanket when the quilt or the blanket well covers the child and turns to be a temperature of a sleeping room or a bedroom when the Tipi event takes place. <EOS>