My new weather station reports the temperature in tenths of a degree. Does a temperature of 38.9 get reported as 38 or as 39?
East Rogers Park, Chicago
It would be reported at 39. The temperature-rounding rules followed by the National Weather Service are straight forward with just one exception. When dealing with positive temperatures any decimal values from .1 to .4 are rounded down and values from .5 to .9 are rounded up, so 61.3 is reported as 61, but 61.5 is recorded as 62. It’s slightly different with negative temperatures. Decimal values from .1 to .5 are rounded to the lower absolute value, while tenths readings from .6 to .9 are rounded to the higher absolute value. For example, readings of -12.5, -12.4, etc., would round to -12, but any readings from -12.6 to -12.9 would be entered as -13.