October 2020 temperatures were above normal, mostly due to the increasingly more frequent trend of recent years of well above normal average minimum temperatures (51.4° or 5.9° above normal). Essentially the average maximum temperature was normal (66.5° or 0.2° above normal). The resulting mean average temperature of 58.9° was 3.0° above normal. My total precipitation of 3.27″ was only 0.16” below the Prism-derived normal value for my station of 3.43”. I am still studying these normal monthly precipitation amounts as they still appear to be lower than I would suspect. There were 9 days with measurable precipitation, with 2.04” falling on the 29th
and 30th. This amount was just about 62% of the monthly total amount. There were 2 dry periods during the month (6-10 with 0 and 13-24 with a few trace (drizzle) amounts). No real tropical systems affected my local area during the month, even though elsewhere in the Atlantic Basin activity remained quite active. Also, there were no thunderstorms falling during the month. A split flow of both easterly and westerly component winds fought it out for dominance during the month. A notable early morning foggy period driven by a persistent easterly marine flow set up in our area during several days of the mid-month period (19th-23rd).

Persistent mild temperatures lasted most of the month, with a downward shift right at the end, when my only sub 40° minimum occurred on the 31st when the monthly lowest min temperature of 36.3° was recorded. No overwhelming warm spells occurred during October. My highest temperature of the month (and only max above 80°) occurred on the 7th when 81.6° was reached. Once again this October failed to reach the freezing mark for the monthly low temperature. I don’t have the exact statistics to back it up, but in the 70s/80s the average first freezing temperature in the fall was around October 20. Now over the past 10 years or so, the average is more like the first
week of November.

The highest daily PWG readings recorded on the University of Shady Grove anemometer across the street were relatively low during October. The highest reading of 34 MPH occurred on the 7th from the W, which also was coincidentally the warmest day of the month.  A total of only 7 days during the month had daily peak wind gusts of 25 MPH or more. 15 of the last 17 days of the month had PWG values less than 20 MPH.

The highest dew point temperature reached during the month was 69° on the 22nd.  12 out of the 15 days between the 10th and 24th had dew point values over 60°. The lowest dew point temperature value was 29°, recorded on the 17th, when the lowest relative humidity value of 33% was also recorded.

The highest barometric pressure reading during October was a fairly respectable 30.56” on the 31st, on our coolest day of the month. The lowest barometric pressure reading for the month occurred just 2 days before on the 29th when 29.39” was reached. That day was the rainiest/ stormiest day of the month. More often than you might think the monthly pressure value extremes occur within a few days of each other. This pattern normally is also reflected in high winds, but that wasn’t the case this month as a PWG of only 20 MPH was reached on the 30th.

October had 11 cloudy, 19 partly cloudy, and 1 clear/sunny days. There were 199 heating degree days and 11 cooling degree days during the month. There were 8 foggy and 1 significantly windy days in October.

My maximum temperature frequencies included 0 days of 90° or greater, 1 day between 80° and 89°, 11 days between 70° and 79°, 15 days between 60° and 69° and 4 days below 60°. On the minimum temperature frequency side of things, there was 1 day in the 30s, 10 days in the 40s, 16 days in the 50s, and 4 days between 60° and 69°. The coolest daily maximum temperature day was 49.9° on the 31st while the warmest daily minimum temperature day of 62.2° was reached on the muggy, rainy 11th.

The diurnal range daily monthly average was 15.1° (- 5.7°). Our greatest daily range of temperature was 28.4° on the 7th on the warmest day of the month (81.6°- 53.2°). Our lowest range of temperature was 5.5° on the cloudy, cool, rainy 30th (51.0°- 45.5°). There were a total of 6 days during the month with single digit daily diurnal ranges and 6 days with ranges greater than 20°.

On my computer/hardware weather station front, I continue to get my tipping bucket clogged frequently with tree and other debris. I still partially rely on the tipping bucket data from the USG station across the street to give me a good indication on how much storm event rainfall I have received plus immediate rainfall rates as it is occurring
before I get my final amount from my daily CoCoRaHS rain gauge reading. The display for this station is now through a Vantage Vue model. The record breaking hurricane season remained active through October, though not in my area but rather in other regions of the Atlantic East and Gulf Coast.

OCTOBER 2020 – ROCKVILLE 2.8 WNW MARYLAND – SUMMARY STATISTICS

Average high temperature                      66.5° (+ 0.2°)
Average low temperature                       51.4° (+ 5.9°)
Mean temperature                                 58.9° (+ 3.0°)
Precipitation                                         3.27″ (- 0.16“)
Greatest daily amount (date)                 1.86″ (29)
Greatest storm total (dates)                  2.04” (29-30)
2020 year-to-date precipitation total      44.69″ (+ 9.46”)
High temperature for the month (date)   81.6° (7)
Low temperature for the month (date)    36.3° (31)
Highest barometric pressure (date)         30.56” (31)
Lowest barometric pressure (date)          29.39” (29)
Peak wind gust (direction/date(s)):         34 W (7)
(USG data across the street)
Heating degree days for the month:        199
Cooling degree days for the month:         11
Greatest diurnal range (date):                28.4° (7)
Least diurnal range (date)                      5.5° (30)
Number of days:
Fog               8
Windy           1 (PWG => 30 MPH)
Hail               0
Thunder        0
Cloudy          11
Partly Cloudy 19
Sunny/Clear   1
Max temp ≥ 80° 1
Min temp < 40°  1
Precip ≥ 0.01”    9

My monthly daily data spreadsheet PDF file: 

2020-10 Rockville 2.8 WNW