Thursday, December 18, 2025

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

THURSDAY, DECEMBER 18, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0709E
SUNSET:  1613E

ABUNDANT SUNSHINE WITH MUCH MILDER TEMPERATURES….

Skies have been mainly clear all day with abundant sunshine giving
us a very beautiful day. Light wind and above normal temperatures
has been a well deserved reprieve today!

Temperatures have warmed into the mid to upper 40s by early this
afternoon. Once again, this is above normal! Dew point values have
been slowly rising up as well, from the mid 20s to the low 30s.

The wind has been much lighter today, averaging at around 9mph.
The peak gust for the day so far is 23mph, which occurred just
before 12:30pm.

Visibility has been decent today, with the view running between
60-70 miles.

The maximum temperature so far today is 47F degrees, which is
7 degrees above the normal high of 40F. The minimum temperature
since midnight is 32F degrees, which is 8 degrees above the
normal low of 24F.

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Today’s Observations:

7 A.M.
Weather: Clear, few cirrus distant all quadrants
Temperature: 34F; Dew Point: 27F; Relative Humidity: 75%
Wind: WSW @ 6 kts, wind light
Sea-level pressure: 1026.9 mb; 30.32 in. Hg: rising, then more slowly
Visibility: 60 miles
6-hr Max temp: 37F
6-hr Min temp: 32F
24-hr Precip: 0.00 inches
24-hr Snowfall: 0.0 inches
Snow Depth: Trace
BHO SA 1155 CLR 60 269/34/27/2406/032/ FEW CI DSNT ALQDS
WND LGT/ 8/001 4/000 51031 10037 20032

10 A.M.
Weather: Clear, few cirrus distant WNW-NE and distant ESE-SSW
Temperature: 41F; Dew Point: 29F; Relative Humidity: 61%
Wind: S @ 4 kts, wind light
Sea-level pressure: 1028.5 mb; 30.37 in. Hg: rising, then more slowly
Visibility: 70 miles
3-hr Precip: 0.00 inches
3-hr Snowfall: 0.0 inches
BHO SA 1455 CLR 70 285/41/29/1904/037/ FEW CI DSNT WNW-NE
AND DSNT ESE-SSW WND LGT/ 8/001 51016

1 P.M.
Weather: Clear, few cirrus distant W-N-NE
Temperature: 47F; Dew Point: 30F; Relative Humidity: 52%
Wind: S @ 7 kts
Sea-level pressure: 1026.7 mb; 30.32 in. Hg: falling, then more rapidly
Visibility: 70 miles
6-hr Max temp: 47F
6-hr Min temp: 34F
6-hr Precip: 0.00 inches
6-hr Snowfall: 0.0 inches
Snow Depth: Trace
BHO SA 1755 CLR 70 267/47/30/1907/032/ FEW CI DSNT W-N-NE/
8/001 4/000 58018 10047 20034

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SUMMARY FOR WEDNESDAY, DECEMBER 17, 2025

TEMPERATURE (DEGREES F)
MAX…….45   NORMAL…..40
MIN…….25   NORMAL…..24
MEAN……35   NORMAL…..32

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….+3
TOTAL DEPARTURE FOR THE MONTH……………………..-113 [-6.8 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY…………….30  DEPARTURE……..-3
TOTAL HEATING UNITS FOR THE MONTH……………632  DEPARTURE……+113
TOTAL HEATING UNITS FOR THE SEASON………….1749  DEPARTURE…….+26
TOTAL HEATING UNITS LAST SEASON TO DATE……..1471  DEPARTURE……+278

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)………..43 SW   @   10:25 A.M.
VECTOR #1 (1-Sec)……….42 SW   @   10:37 A.M.
VECTOR #2 (1-Sec)……….41 SSW  @   08:03 A.M.
DAVIS #1……………….50 S    @   07:13 A.M.
DAVIS #2 ………………40 SW   @   08:03 A.M.
RMY #1 (Instantaneous)…..43 SW   @   10:25 A.M.
RMY #2 (Instantaneous)…..47 SSW  @   07:59 A.M.
MERLIN…………………38 S
RICHARDS (C5C) (Inst)……45 SW   @   10:25 A.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………29 SW   @   09:00 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..29 SW   @   11:18 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..29 SW   @   11:18 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………28 SW   @   11:18 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………29 SW   @   11:18 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..29 SW   @   11:18 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..29 SW   @   11:18 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………27 SW   @   10:26 A.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL……..18.0 SW [432 total miles] VECTOR #1………………17.5
VECTOR #2………………18.4
DAVIS #1……………….17.5 SW
DAVIS #2……………….18.4 WSW
RMY #1…………………17.2 SW
RMY #2…………………18.3 SW
RICHARDS (C5C)………….16.1

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.18
TOTAL PRECIPITATION FOR THE MONTH…………..1.08 DEPARTURE…..-1.96
TOTAL PRECIPITATION FOR THE YEAR (2025)…….45.54 DEPARTURE…..-5.97

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..0.0 DEPARTURE…..-0.4
TOTAL SNOWFALL FOR THE MONTH………………..2.4 DEPARTURE…..-3.3
TOTAL SNOWFALL FOR THE SEASON (2025-2026)…….2.5 DEPARTURE…..-5.7

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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  The low since midnight is 32F, the daily normal low is 24F.

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DECEMBER DAILY RECORDS TO DATE

NONE.

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

RECORDS FOR DECEMBER 18
HIGH 61 IN 2023
LOW -11 IN 1919
PRECIP 2.47 INS. IN 2023
SNOWFALL 7.0 INS. IN 1904
PEAK GUST 90 SSE IN 2023

RECORDS FOR DECEMBER 19
HIGH 59 IN 1899
LOW -1 IN 1919
PRECIP 2.06 INS. IN 1986
SNOWFALL 14.1 INS. IN 1945
PEAK GUST 68 NE IN 1986

TODAY’S REPORT PREPARED BY: Matt Douglas