A box is plotted for each month of the year that has data. The extents of the black box mark the
lower quartile (25% of data values are less than this value) and upper quartile (75% of data values
are less than this value), a red line indicates the median, and a dark green line indicates the
mean. The black lines above and below the box, the "whiskers", show the extent of the remaining data
but have a maximum length of 1.5L, where L is the length in meters from the lower quartile to the
upper quartile. Data values that extend beyond the whiskers are "outliers" and are indicated with
red crosses.