OCTOBER 2018 MONTHLY SUMMARY FOR ROCKVILLE 2.8 WNW MARYLAND
by Kevin Shaw, Observer in Charge
October 2018 was warm and dry. It was the driest month of this year since 1.62″ was recorded in March.
This reversed the generally wet pattern of the past months, particularly the July-September period. The
first 11 days of the month were warm, with 8 maximum temperatures of 80° or greater, and averaged 73.2°.
The last 20 days of the month contrasted significantly with consistently below normal temperatures, averaging
51.0°. The strong front that passed through on the 11th marked the change with the wettest calendar day
of the month (0.91″) All but 0.01″ of the month’s precipitation fell on the 11th or later. The rainfall on the
11th were from the remnants of Hurricane Michael. Another storm, more of the nor’easter type, fell from
the 26th till early on the 28th with a storm total of 1.24″. At the end of the month I still didn’t have a
freezing low temperature, but I did have some frosty mornings during the later days of October. Fall color
change was delayed, and peaked in early November. It was a rapid change after much of the month still had
predominantly green foliage. The year to date rainfall amount of 51.05″ was still well above normal, and many
Maryland stations look to break long term annual rainfall records.
The highest temperature reached during the month was 85.6° on the 4th while the lowest temperature in
October was a frosty 33.7° on the 22nd. The highest dew point temperature reached during the month
was 75° during our early month warm, humid spell on several days (4,7,8,11) while the lowest dew point
temperature value reached during the month was 30° on the 18th and 25th.
Barometric pressure differences during the month increased a bit over the previous few months, with the
lowest values found on the 11th and 12th, when 29.52” was reached during the passage of Hurricane
Michael remnants. The nor’easter on the 26th only reached a low of 29.60”. October’s highest pressure
value for the month (30.46”) occurred on the chilly, dry 18th.
October had 8 cloudy days, 14 partly cloudy days, and 9 clear/sunny days. There were 281 heating degree
days and 90 cooling degree days during the month. There were 9 foggy days, 7 windy days, and only 1 day
with thunder The windy day category is subjective with no personal real data values to back it, just based
on my descriptive email daily weather posts that are posted on weathertogether.net.
Daily max/min temperatures varied a bit more than the previous hot, humid summer months. My maximum
temperature frequencies included 8 days between 80° and 89°, 3 days between 70° and 79°, 8 days
between 60° and 69°, 10 days between 50° and 59°, and 2 days below 50°. On the minimum temperature
frequency side of things, there were 6 days between 30° and 39°, 11 days between 40° and 49°, 3 days
between 50° and 59°, 8 days between 60° and 69° and 3 days above 70°. The coolest daily max
temperature was 47.1° on the 26th with the warmest daily min temp of 70.3° on the 8th and 9th.
The diurnal range daily monthly average was 14.2°. Our greatest daily range of temperature was a
comfortable 25.7° on the 23rd, formed from a high of 66.7° and the low of 41.0°. We had a total
of 6 days with daily ranges at or above 20.0°. Our lowest range of temperature was 4.5° (50.1°-46.5°)
on the 27th during the aforementioned nor’easter I had. There were 4 total days with diurnal temperature
ranges of less than 10.0°, mostly during the nor’easter. The generally drier days helped expand our diurnal
ranges somewhat from the low values of a wetter September.
Fortunately I had no more power (battery) problems with my VP2 weather station as I did in September.
I am still constantly checking on my data quality frequently, along with discussion and data comparison with
several of my Maryland weather cohorts and reliable online close by observer data. I have begun to prepare
my outside components for the winter, such as removal of the inner cylinder and funnel to aide in collecting
snow and other freezing precipitation types. I continue to occasionally (as time allows) submit GLOBE Cloud
observations, complete with submission of sky pictures at the time of the observation, usually timed with the
passage of satellites and/or solar noon (about 70 minutes past actual EDT noon). Please ask me any questions
you want at any time about my station setup and/or my data through any means available to you.
OCTOBER 2018 – ROCKVILLE 2.8 WNW MARYLAND – SUMMARY STATISTICS
Average high temperature 65.9°
Average low temperature 51.8°
Mean temperature 58.9°
Precipitation 2.63″ (- 0.77”) (long-term PRISM normals)
Greatest daily amount (date) 0.91″ (11)
Greatest storm total (dates) 1.24” (26-28)
2018 year-to-date precipitation total 51.05″
High temperature for the month (date) 85.6° (4)
Low temperature for the month (date) 33.7° (22)
Highest barometric pressure (date) 30.46” (18)
Lowest barometric pressure (date) 29.52” (11,12)
Peak wind gust (date/direction): N/A
Heating degree days for the month: 281
Cooling degree days for the month: 90
Greatest diurnal range (date): 25.7° (23)
Least diurnal range (date) 4.5° (27)
Number of days:
Partly Cloudy 14
Max temp ≥ 80° = 8
Min temp < 40°= 9
Precip ≥ 0.01” = 9