void setup() {
  Serial.begin(115200); Serial.println();
  uint8_t time_hour = 8, time_min = 22, time_sec = 33;
  float temperature = 22.57;
  String message = "Minimum temperature of  ";
  message += String(temperature, 1); // just 1 digit after decimal point
  message += "°C reached at ";
  message += String(time_hour);
  message += "h";
  message += String(time_min);
  message += " and ";
  message += String(time_sec);
  message += " second";
  if (time_sec > 1) message += "s";
  // message now holds "Minimum temperature of 22.5°C reached at 8h22 and 33 seconds"
  Serial.println(message);
}

void loop() {}