Wednesday, December 3, 2014

Why do we strive to be 'near normal'?

It always feels like some sort of resolution when temperatures return to 'normal' for whatever time of year it happens to be. Like hitting the last note of a song after a harsh dissonance, or lack of harmony. 

Highs in the 70s? That's a normal May day. 
Lows in the 20s? That's a normal December day. 

But how often do we really achieve a 'normal' high temperature?

Using the month of November as an example, here are the normal highs, according to the National Weather Service's records and the actual highs recorded for the month:

                                    AVERAGE HIGHS:                                ACTUAL HIGHS:
1-Nov 57 1-Nov 40
2-Nov 56 2-Nov 47
3-Nov 56 3-Nov 60
4-Nov 55 4-Nov 55
5-Nov 55 5-Nov 58
6-Nov 55 6-Nov 48
7-Nov 54 7-Nov 46
8-Nov 54 8-Nov 45
9-Nov 53 9-Nov 45
10-Nov 53 10-Nov 60
11-Nov 52 11-Nov 64
12-Nov 52 12-Nov 37
13-Nov 51 13-Nov 35
14-Nov 51 14-Nov 33
15-Nov 50 15-Nov 32
16-Nov 50 16-Nov 33
17-Nov 49 17-Nov 30
18-Nov 49 18-Nov 18
19-Nov 48 19-Nov 33
20-Nov 48 20-Nov 27
21-Nov 47 21-Nov 26
22-Nov 46 22-Nov 51
23-Nov 46 23-Nov 58
24-Nov 45 24-Nov 58
25-Nov 45 25-Nov 35
26-Nov 44 26-Nov 33
27-Nov 44 27-Nov 33
28-Nov 43 28-Nov 30
29-Nov 43 29-Nov 51
30-Nov 42 30-Nov 62
On only ONE single day out of 30, we actually matched the normal high temperature for this time of year.


That's a 3.33% occurrence.

A few times, we came close [Nov 3: 56/60°, Nov 5: 55/58°], but being consistently spot on with 'normal' temperatures is uncommon.

Does it matter? Not really. Monthly average temperatures can dictate the overall season, but if you have 15 days in the 30s and 15 days in the 50s, the average will still round out to be in the 40s.

Despite that, averages-- normals, typical temperatures-- are still important.
Averages factor in roughly 140 years of data, so while we may see larger temperature swings from day to day, over a long period of time, eventually an average will balance out.

For all recorded locations and cities, for every month, the average tells us what a typical day might be. That's the purpose it should serve, and actually matching those figures isn't something we need to strive for.