Saturday, December 20, 2025

BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA

SATURDAY, DECEMBER 20, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0710E
SUNSET:  1614E

COLD AIR RETURNS, PLENTY OF SUNSHINE….

Following the passage of a cold front and departure of yesterday’s
storm system, skies cleared for the morning aside from a few distant
stratocumulus. Some thin upper level clouds moved in from the southwest
for the early afternoon, filtering the sunshine somewhat.

The brief warm up we experienced yesterday due to strong southerly flow
has quickly come to an end, with a cold, dry air mass moving back into place.
The low this morning was in the upper 20s, with a high so far in the mid 30s.
The dew point has remained in the upper teens.

Winds were steady through the early morning hours, before dropping
off quite dramatically right around sunrise. The average speed for the
day so far is 15mph, primarily out of the west-northwest. The peak gust
is approximately 46mph, occurring shortly after 2am this morning.

Visibility is excellent today, with views reaching up to 70 miles by
the late morning hours.

The maximum temperature so far today is 36F degrees, which is
3 degrees below the normal high of 39F. The minimum temperature
since midnight is 27F degrees, which is 3 degrees above the
normal low of 24F.

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Today’s Observations:

7 A.M.
Weather: Clear, few stratocumulus distant NE-SW
Temperature: 27F; Dew Point: 18F; Relative Humidity: 67%
Wind: WNW @ 13G21 kts, peak wind WNW 32mph at 05:59 A.M.
Sea-level pressure: 1016.0 mb; 30.00 in. Hg: rising, then more rapidly
Visibility: 50 miles
6-hr Max temp: 32F
6-hr Min temp: 27F
24-hr Precip: 0.58 inches
24-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1155 CLR 50 160/27/18/3013G21/000/ FEW SC DSNT NE-SW PRESRR PK WND
2928/1059/ 8/500 53059 70058 10032 20027

10 A.M.
Weather: Clear, few altocumulus distant S-WSW
Temperature: 32F; Dew Point: 20F; Relative Humidity: 60%
Wind: WNW @ 8 kts
Sea-level pressure: 1019.5 mb; 30.11 in. Hg: rising unsteadily
Visibility: 70 miles
3-hr Precip: 0.00 inches
3-hr Snowfall: 0.0 inches
BHO SA 1455 CLR 70 195/32/20/3008/011/ FEW AC DSNT S-WSW/ 8/050 52035

1 P.M.
Weather: Thin scattered cirrus, few altocumulus distant SW-N,
few cirrostratus all quadrants
Temperature: 36F; Dew Point: 18F; Relative Humidity: 47%
Wind: W @ 7 kts
Sea-level pressure: 1019.3 mb; 30.10 in. Hg: rising, then falling
Visibility: 70 miles
6-hr Max temp: 36F
6-hr Min temp: 27F
6-hr Precip: 0.00 inches
6-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1755 250 -SCT 70 193/36/18/2707/010/ FEW AC DSNT SW-N
FEW CS ALQDS/ 8/055 58002 10036 20027

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SUMMARY FOR FRIDAY, DECEMBER 19, 2025

TEMPERATURE (DEGREES F)
MAX…….58   NORMAL…..39
MIN…….32   NORMAL…..24
MEAN……45   NORMAL…..32

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL……………+13
TOTAL DEPARTURE FOR THE MONTH………………………-92 [-5.0 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY…………….20  DEPARTURE…….-13
TOTAL HEATING UNITS FOR THE MONTH……………677  DEPARTURE…….+91
TOTAL HEATING UNITS FOR THE SEASON………….1794  DEPARTURE……..+4
TOTAL HEATING UNITS LAST SEASON TO DATE……..1521  DEPARTURE……+273

PEAK WIND GUST (MPH):
Note: Instruments designated #1 = Main Tower, #2 = South Tower,
F420C, Contacting, Merlin, and Richards are all on Main Tower.
E=Estimated *=Last of multiple occurrences

F420C (Official)………..79 S    @   11:48 A.M.
VECTOR #1 (1-Sec)……….79 S    @   11:48 A.M.
VECTOR #2 (1-Sec)……….79 SSE  @   11:48 A.M.
DAVIS #1……………….81 S    @   12:46 P.M.
DAVIS #2 ………………95 S    @   11:02 A.M.
RMY #1 (Instantaneous)…..81 S    @   11:48 A.M.
RMY #2 (Instantaneous)…..86 SSE  @   11:48 A.M.
MERLIN…………………73 S
RICHARDS (C5C) (Inst)……79 S    @   11:48 A.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………54 SSE  @   11:49 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..53 SSE  @   11:49 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..55 SSE  @   11:26 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………49 SSE  @   11:50 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………62 S    @   12:14 P.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..51 SSE  @   11:49 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..52 SSE  @   11:26 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………52 S    @   11:50 A.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL……..24.1 S [578 total miles] VECTOR #1………………23.1
VECTOR #2………………24.7
DAVIS #1……………….22.6 SSW
DAVIS #2……………….25.3 SSW
RMY #1…………………22.1 SSW
RMY #2…………………24.0 SSW
RICHARDS (C5C)………….22.3

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.58 DEPARTURE…..+0.40
TOTAL PRECIPITATION FOR THE MONTH…………..1.68 DEPARTURE…..-1.71
TOTAL PRECIPITATION FOR THE YEAR (2025)…….46.14 DEPARTURE…..-5.72

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..0.0 DEPARTURE…..-0.5
TOTAL SNOWFALL FOR THE MONTH………………..2.4 DEPARTURE…..-4.2
TOTAL SNOWFALL FOR THE SEASON (2025-2026)…….2.5 DEPARTURE…..-6.6

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PRELIMINARY CLIMATE SUMMARY FOR DECEMBER CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN)/SUN(%)/PEAK GUST/VEC1/RMY GUST
PEAK GUST: F420C (Official)
VEC1: Vector #1 1-second gust
RMY:  R.M. Young #1 wind gust recording system (Instantaneous)
TSTM: Thunderstorm day (thunder heard some time during day)
….: Data not yet available, records not finalized
M:    Missing data

12/1   42/27/35/-2/T/0.0/547/98          37 WNW VEC1 37 WNW RMY 38
12/2   36/27/32/-5/0.85/T/000/00         38 N   VEC1 38 NNE RMY 38
12/3   37/27/32/-4/0.06/0.6/423/76       28 NW  VEC1 29 NNW RMY 30
12/4   38/15/27/-9/T/T/255/46            60 NW  VEC1 59 WNW RMY 61
12/5   25/8/17/-19/T/T/510/92            30 NW  VEC1 30 NW  RMY 30
12/6   39/25/32/-3/T/T/122/22            21 W   VEC1 21 W   RMY 22
12/7   39/27/33/-2/0.00/0.0/248/45       24 W   VEC1 24 W   RMY 24
12/8   31/12/22/-13/T/T/457/83           43 NW  VEC1 43 NW  RMY 44
12/9   28/9/19/-15/0.00/0.0/452/82       33 SSW VEC1 33 SSW RMY 33
12/10  46/28/37/+3/0.04/T/187/34         50 SSW VEC1 50 SSW RMY 51
12/11  37/21/29/-5/0.00/0.0/450/82       51 WNW VEC1 51 WNW RMY 53
12/12  33/18/26/-8/0.00/0.0/532/97       41 W   VEC1 41 W   RMY 42
12/13  34/23/29/-4/0.00/0.0/038/07       28 SW  VEC1 28 SW  RMY 31
12/14  31/15/23/-10/0.13/1.8/000/00      39 NNW VEC1 39 NNW RMY 40
12/15  23/10/17/-16/0.00/0.0/496/91      40 NW  VEC1 40 NW  RMY 42
12/16  36/19/28/-4/0.00/0.0/437/80       29 SW  VEC1 29 SW  RMY 30
12/17  45/25/35/+3/0.00/0.0/196/36       43 SW  VEC1 42 SW  RMY 43
12/18  47/32/40/+8/0.00/0.0/…/..       32 S   VEC1 32 S   RMY 34
12/19  58/32/45/+13/0.60/0.0/…/..      79 S   VEC1 79 S   RMY 81

12/20  The low since midnight is 27F, the daily normal low is 24F.

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DECEMBER DAILY RECORDS TO DATE

12/19 PEAK GUST OF 79 MPH S,
BEAT THE OLD RECORD OF 68 MPH NE IN 1986.

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DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated)

RECORDS FOR DECEMBER 20
HIGH 61 IN 1957
LOW -16 IN 1942
PRECIP 1.69 INS. IN 1936
SNOWFALL 13.7 INS. IN 2009
PEAK GUST 75 MPH S IN 2002

RECORDS FOR DECEMBER 21
HIGH 62 IN 2018
LOW -10 IN 1942
PRECIP 2.37 INS. IN 1946
SNOWFALL 11.4 INS. IN 1954
PEAK GUST 77 MPH SSE IN 1957

TODAY’S REPORT PREPARED BY: Joshua Polen