Intro and Summary

In the wake of record low temperatures overnight in Seattle this month (and some previous analysis I did on “high-low” temperatures several years ago) I decided to take a look at some more weather data.

data Description

A Century of weather data. Includes daily high an low temperatures from Aberdeen, WA (a timber and shipping town on the Pacific Coast) shows that while daytime highs have remained relatively constant ove the last hundred years, nighttime temperatures have increased by about 4 degrees Fahrenheit over the last century. The increase is monotonic and appears to be relatively linear.

Nighttime warming is an expected outcome of the greenhouse effect.

data

Here is a snapshot of the data.

## # A tibble: 36,490 × 5
##    NAME            DATE        TMIN  TMAX  PRCP
##    <chr>           <date>     <dbl> <dbl> <dbl>
##  1 ABERDEEN, WA US 1922-01-06    29    42  0   
##  2 ABERDEEN, WA US 1922-01-07    32    42  0.22
##  3 ABERDEEN, WA US 1922-01-08    37    47  0   
##  4 ABERDEEN, WA US 1922-01-09    41    48  0.4 
##  5 ABERDEEN, WA US 1922-01-10    35    46  0   
##  6 ABERDEEN, WA US 1922-01-11    30    40  0   
##  7 ABERDEEN, WA US 1922-01-12    34    46  0   
##  8 ABERDEEN, WA US 1922-01-13    28    47  0   
##  9 ABERDEEN, WA US 1922-01-14    28    36  0   
## 10 ABERDEEN, WA US 1922-01-15    30    46  0   
## # … with 36,480 more rows

Nighttime Temperatures have warmed 4 degrees F

this is a simple plot of the low temperature data. An increase in apparent when a smoothing line (in this case just a rough spline fit) is added.

The mean low at the start of the period is 40 degrees F and at the end is 44.1 degrees F.

Annually, low temperatures warmed 0.41 degrees F per decade.

Daytime Temperatures are relatively constant

These do not show a shift.

Warming is primarily in Summer

Low Temperatures show a one month shift toward summer

Within the summer months low nighttime temperatures have increased most dramatically.

The mean lows for July and August at the start of the period is 49.1 degrees F and at the end is 54.8 degrees F.

Low temperatures in the summer have warmed 0.57 degrees F per decade over the last Century.

Conclusions:

1. Long term temperature increases are observable in weather data for Aberdeen, WA, USA.
2. Warming trends in daily low (nighttime) temperatures increase about 0.4 degrees F per decade.
3. Daily high (daytime) temperatures are relatively constant.
4. Nighttime warming is observed primarily in the summer months.

fin