January was warm, but in a weird way

Did last month feel warm to you? January was unusually warm in central Indiana, but in a subtle way. The highest temperature recorded at the Purdue University Airport (KLAF) was 63°F — just four degrees warmer than last year. And the lowest temperature — -4°F — was a degree colder than last year. But what if last year was warm, too?

Let’s compare January 2017 to the climate normals (1981-2010). The average daily high was 5.4 degrees above normal, and the average daily low was 5.9 degrees above normal. The average temperature for the month was 5.6 degrees above normal. That’s noticeably warm, but not necessarily outrageous.

What makes January 2017 stand out is the extended stretch of warmer temperatures. More specifically, how it just wasn’t freezing for much of the month. January 2017 was right on target for number of days with a low below zero (3), but it had five fewer days than normal with a low below 32°F. In fact, Lafayette set a new record for consecutive hours in January with a temperature above freezing.

Chart of 1995 and 2017 above-freezing streaks.

Streaks of January hourly temperatures at or above freezing at KLAF. Chart from Iowa Environmental Mesonet.

Since records began at KLAF in 1972, only two years have had a 10-day or longer above freezing streak. In 1995, we had a 10-day streak. This year it was 10.9 days. It just didn’t get cold for the second half of the month. Four of the last 10 Januaries had at least 5 days with a high temperature above 50°F. Four of the last 10 years also had at least one January day above 60°F. This year’s 2 is bested by 3 in 2008.

So if you were thinking to yourself “wow, January was really warm” but the high temperatures didn’t look all that off, rest assured that it was. It just forgot to January.

Full monthly climate report:

CLIMATE REPORT
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1113 AM EST WED FEB 1 2017

...................................

...THE LAFAYETTE IN CLIMATE SUMMARY FOR THE MONTH OF JANUARY 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 9999 TO 9999

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
HIGHEST            63   01/21                         59  01/31
LOWEST             -4   01/07                         -3  01/13
AVG. MAXIMUM     39.4              34.0     5.4     35.5
AVG. MINIMUM     24.9              19.0     5.9     18.3
MEAN             32.1              26.5     5.6     26.9
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32     10              12.9    -2.9       13
DAYS MIN <= 32     21              25.8    -4.8       28
DAYS MIN <= 0 3 3.1 -0.1 2

PRECIPITATION (INCHES)
TOTALS 4.00 1.86 2.14 1.08 DAILY AVG. 0.13 0.06 0.07 0.03
DAYS >= .01        12               8.7     3.3        6
DAYS >= .10        10               4.0     6.0        4
DAYS >= .50         3               0.8     2.2        1
DAYS >= 1.00        0               0.3    -0.3        0
GREATEST
 24 HR. TOTAL    1.15   01/19 TO 01/20

DEGREE_DAYS
HEATING TOTAL    1013              1193    -180     1172
 SINCE 7/1       2997              3368    -371     2853
COOLING TOTAL       0                 0       0        0
 SINCE 1/1          0                 0       0        0
.................................................................

WIND (MPH)
AVERAGE WIND SPEED              8.9
HIGHEST WIND SPEED/DIRECTION    40/270    DATE  01/10
HIGHEST GUST SPEED/DIRECTION    55/270    DATE  01/10

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.70
NUMBER OF DAYS FAIR            7
NUMBER OF DAYS PC              7
NUMBER OF DAYS CLOUDY         17

AVERAGE RH (PERCENT)     84

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              5     MIXED PRECIP               0
HEAVY RAIN                6     RAIN                       7
LIGHT RAIN               10     FREEZING RAIN              1
LT FREEZING RAIN          1     HAIL                       0
HEAVY SNOW                0     SNOW                       1
LIGHT SNOW                7     SLEET                      0
FOG                      21     FOG W/VIS <= 1/4 MILE      1
HAZE                      4

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.

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