function updateAverage(averageAsOfYesterday, todayTemp, todayDayOfYear) {
      yesterdayDayOfYear = todayDayOfYear - 1
      sumOfAllTempsUpToAndIncludingYesterday = yesterdayDayOfYear * averageAsOfYesterday
      return (sumOfAllTempsUpToAndIncludingYesterday + todayTemp) / todayDayOfYear
  }