Friday, September 12, 2025

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

FRIDAY, SEPTEMBER 12, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0521E
SUNSET:  1759E

MOSTLY SUNNY SKIES TODAY WITH INCREASING PM CLOUDS….

Today has been similar to yesterday, as we have had plenty
of sunshine. By the early afternoon we had increasing clouds,
mostly from daytime heating. Still though, it’s been an
overall comfortable day with seasonable temperatures and a
gentle sea breeze.

Temperatures overnight were not as cool as the previous night,
but we still managed to near normal temperatures. The temperature
steadily rose as the day progressed, but so far we are still
just below normal values. Dew points have also remained in the
mid 50’s, which is still comfortable, though high enough to
impact the visibility just slightly.

We have had a sea breeze for much of the day today, with an
average speed so far of around 11mph. We have had gusts in
the 15-20mph range, with heavier gusts occurring in the early
morning hours. By afternoon the wind had decreased quite a
bit and became variable. The peak gust so far is 24mph, which
occurred just before 1:30am this morning.

Visibility has been pretty decent today with a view of about 50 miles
throughout the day.

The maximum temperature so far today is 70F degrees, which is 4
degrees below the normal high of 74F. The minimum temperature
since midnight is 56F degrees, which is 1 degree below the normal
low of 57F.

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Today’s Observations:

7 A.M.
Weather: Clear, few altocumulus NW-NNE-ESE
Temperature: 60F; Dew Point: 52F; Relative Humidity: 74%
Wind: NNE @ 10G18 kts
Sea-level pressure: 1023.5 mb; 30.22 in. Hg: rising, then
more slowly
Visibility: 50 miles
6-hr Max temp: 56F
6-hr Min temp: 51F
24-hr Precip: 0.00 inches
BHO SA 1155 CLR 50 235/60/52/0310G18/022/ FEW AC NW-NNE-ESE/
8/050 51014 10063 20056

10 A.M.
Weather: Clear, few cumulus all quadrants, few altocumulus
NW-NE
Temperature: 66F; Dew Point: 53F; Relative Humidity: 63%
Wind: ENE @ 9G18 kts
Sea-level pressure: 1024.6 mb; 30.26 in. Hg: falling, then
more slowly
Visibility: 50 miles
3-hr Precip: 0.00 inches
BHO SA 1455 CLR 50 246/66/53/0709G18/026/ FEW CU ALQDS
FEW AC NW-NE/ 8/250 51011

1 P.M.
Weather: Scattered cumulus
Temperature: 69F Dew Point: 54F; Relative Humidity: 58%
Wind: NE @ 4 kts, wind light and variable
Sea-level pressure: 1024.0 mb; 30.24 in. Hg: steady, then
falling
Visibility: 50 miles
6-hr Max temp: 70F
6-hr Min temp: 63F
6-hr Precip: 0.00 inches
BHO SA 1755 45 SCT 50 240/69/54/0504/024/ WND L/V/ 8/200
58006 10070 20063

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SUMMARY FOR THURSDAY, SEPTEMBER 11, 2025

TEMPERATURE (DEGREES F)
MAX…….77   NORMAL…..74
MIN…….51   NORMAL…..57
MEAN……64   NORMAL…..66

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….-2
TOTAL DEPARTURE FOR THE MONTH………………………-22 [-2.2 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY……………..1  DEPARTURE……..-1
TOTAL HEATING UNITS FOR THE MONTH…………….21  DEPARTURE……..+6
TOTAL HEATING UNITS FOR THE SEASON……………41  DEPARTURE……..+8
TOTAL HEATING UNITS LAST SEASON TO DATE……….21  DEPARTURE…….+20

COOLING DEGREE DAYS (SEASON JAN 2025 THRU DEC 2025)
TOTAL COOLING UNITS FOR YESTERDAY……………..0  DEPARTURE……..-3
TOTAL COOLING UNITS FOR THE MONTH…………….27  DEPARTURE…….-16
TOTAL COOLING UNITS FOR THE SEASON…………..699  DEPARTURE…….+60
TOTAL COOLING UNITS LAST SEASON TO DATE………719  DEPARTURE…….-20

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

F420C (Official)………..18 N    @   11:21 P.M.
VECTOR #1 (1-Sec)……….17 N    @   11:08 P.M.
VECTOR #2 (1-Sec)……….20 N    @   11:16 P.M.
DAVIS #1……………….16 NNW  @   04:00 A.M.
DAVIS #2 ………………16 NNW  @   06:54 A.M.
RMY #1 (Instantaneous)…..18 N    @   11:21 P.M.
RMY #2 (Instantaneous)…..19 N    @   11:16 P.M.
MERLIN…………………19 N
RICHARDS (C5C) (Inst)……17 N    @   11:21 P.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………13 NNW  @   02:44 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..13 NNW  @   02:44 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..13 N    @   11:23 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………13 NNW  @   03:53 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………13 N    @   04:02 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..13 NNW  @   03:54 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..13 NNW  @   04:02 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………13 NNW  @   03:54 A.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………6.8 NNW [163 total miles] VECTOR #1……………….7.5
VECTOR #2……………….7.7
DAVIS #1………………..7.2 NNW
DAVIS #2………………..7.1 N
RMY #1………………….7.3 NNW
RMY #2………………….7.6 NNW
RICHARDS (C5C)…………..7.8

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.12
TOTAL PRECIPITATION FOR THE MONTH…………..2.14 DEPARTURE…..+0.83
TOTAL PRECIPITATION FOR THE YEAR (2025)…….33.47 DEPARTURE…..-2.45

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PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/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

9/1   73/55/64/-5/0.00/221/28            23 NE  VEC1 23 ENE RMY 23
9/2   77/58/68/-1/0.00/714/91            18 ESE VEC1 19 ESE RMY 18
9/3   78/57/68/0/0.00/719/92             21 SSW VEC1 21 SSW RMY 21
9/4   81/56/69/+1/0.00/…/..            26 SSW VEC1 27 SSW RMY 28
9/5   82/63/73/+5/0.12/…/..            30 SSW VEC1 31 SSW RMY 33
9/6   84/64/74/+6/1.05/…/..            55 W   VEC1 55 W   RMY 57 TSTM
9/7   64/56/60/-7/0.97/…/..            16 WNW VEC1 16 NNE RMY 15
9/8   68/49/59/-8/0.00/…/..            21 NW  VEC1 21 NW  RMY 24
9/9   70/53/62/-5/0.00/…/..            22 ENE VEC1 23 E   RMY 23
9/10  65/54/60/-6/0.00/…/..            24 NE  VEC1 25 NE  RMY 25
9/11  77/51/64/-2/0.00/…/..            21 N   VEC1 17 N   RMY 18

9/12 The low since midnight is 56F, the daily normal low is 57F.

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SEPTEMBER 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 SEPTEMBER 12
HIGH 92F IN 1961
LOW 42F IN 1958,1967,1985
PRECIP 2.79 INCHES IN 1960 (HURRICANE DONNA)
PEAK GUST 140 MPH SSE IN 1960 (HURRICANE DONNA)

RECORDS FOR SEPTEMBER 13
HIGH 91F IN 1957
LOW 40F IN 1985
PRECIP 3.10 INCHES IN 1987
PEAK GUST 44 MPH WNW IN 1986

TODAY’S REPORT PREPARED BY: Amanda Joly