January 2021 was milder and drier than normal. My maximum temperature average (41.3°) was 0.5° above normal but my minimum temperature average (30.1°) was much more significantly above normal (+ 5.6°), resulting in the mean temperature average of 35.9° to be 2.9° above normal. These are quite similar to my December 2020 temperature averages and departures. My total precipitation of 2.10″ was 0.81” below the normal January value for my station of 2.91”. There were 10 days with measurable precipitation, roughly 65% of which occurred during the first three days of the month (1.36”). Over 75% of the month’s total snow (3.1” out of 4.0” total) fell on the 31st. Other measureable snowfall amounts occurred on the 21st (0.1”)
and 25th (0.8”). The new year-to-date precipitation starts out at 2.10”. Seasonal snowfall was 6.3” through January 31. February has added considerably more to that total.

There was one moderately cold spell during the month, as between the 23rd and the 31st all but one day registered max temps in the 30s. Most all of our monthly snow fell during this period. Minimum temps were mostly in the 20s but no day during the whole month reached down into the teens. The coldest day of the month was on the 29th (30.9°) while the lowest min temp of the month (21.5°) was reached on the following morning on the 30th. There
was a notable lack of significantly high temperatures during the month as only 3 days reached the 50s (max value reached 53.1° on the 2nd) .

The monthly maximum daily precipitation amount of 0.97″ was reached on New Years Day. The three day total of 1.36” from the 1st-3rd was the greatest multi-day rain event of the month. The extreme barometric pressure readings of the month exhibited unusual traits with respect to their extreme values. The highest value of 30.54” on the 1st occurred on the wettest day of the month, and the lowest value of 29.51” on the 16th occurred on a totally dry day

The highest dew point temperature reached during the month was 48° during that 3 day wet spell on the 2nd, whereas the lowest dew point value of 8° occurred on the coldest max temp day of the month on the 29th.

January had 10 cloudy, 15 partly cloudy, and 6 clear/sunny days, probably about normal for this time of year. There were 901 heating degree days and no cooling degree days during the month. There were 6 foggy days, 10 windy days, 4 days with snow and 1 day (each) with glaze and sleet. The peak wind gust noted during December was 41 MPH from the W on the 28th. On the other hand, 14 days had PWG values below 20 MPH, highlighted by the month’s
low PWG of 10 MPH from the E on the 26th.

My maximum temperature frequencies included 3 days between 50° and 59°, 18 days between 40° and 49°, and 10 days below 40°. On the minimum temperature frequency side of things, there were 12 days below 30° and 19 days between 30° and 39° (and 19 days of freezing or
below mins). The coldest daily max temperature day was 30.9° on the 29th while the warmest daily min temp day of 37.5° was reached on the 5th.

The diurnal range daily monthly average was only 11.7° (- 5.1°). Our greatest daily range of temperature was 26.3° on the 21st (50.3°- 24.0°). We had a total of only 2 days with daily ranges above 20°. Our lowest range of temperature was only 2.3° (39.8°- 37.5°) on
the 5th. There were 10 days with diurnal temperature ranges of less than 10° during the month, half during the first 10 days of the month, the other half during
the last 10 days of the month.

January 2021 was a bit dry with no real daily extremes of temperature and precipitation. Amazingly enough once again the monthly minimum temperature did not reach into the teens at all. There was no real ice formation on local ponds through the end of the month.
I had to start estimating water equivalents of the snow on the 31st due to physical problems that have continued through many icy events in February.

Safety first!!!

January 2021 PDF excel data file

2021-01 Rockville 2.8 WNW

JANUARY 2021 – ROCKVILLE 2.8 WNW MARYLAND
SUMMARY STATISTICS

Average high temperature 41.8° (+ 0.5°)
Average low temperature 30.1° (+ 5.6°)
Mean temperature 35.9° (+ 2.9°)
High temperature for the month (date) 53.1° (2)
Low temperature for the month (date) 21.5° (30)

Precipitation 2.10″ (- 0.81“)
Greatest daily amount (date) 0.97″ (1)
Greatest storm total (dates) 1.36” (1-3)
2021 year-to-date precipitation total 2.10″ (- 0.81”)
Snow 4.0”

Highest barometric pressure (date) 30.54” (1)
Lowest barometric pressure (date) 29.51” (16)

Peak wind gust (date/direction): 41 (28/W)
(USG data across the street)

Heating degree days for the month: 901
Cooling degree days for the month: 0

Greatest diurnal range (date): 26.3° (21)
Least diurnal range (date) 2.3° (5)

Number of days:

Fog 6
Windy 9
Glaze 1
Sleet 1
Snow 4
Cloudy 10
Partly Cloudy 15
Sunny/Clear 6
Max temp = 50° 3
Min temp <= 32° 19
Max temp <= 32° 2
Precip = 0.01” 10