Tuesday, September 16, 2025

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

TUESDAY, SEPTEMBER 16, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0526E
SUNSET:  1752E

DENSE FOG BURNS OFF TO A MIX OF SUN AND CLOUDS….

The day started with dense fog and visibility that dropped as
low as 1/8th of a mile early this morning. The low clouds and
fog burned off by mid morning leaving with quite a bit of
high cirrus clouds. This is creating a mix of sun and clouds
once again for today.

Temperatures are a bit on the cool side today thanks to the wind
off the ocean. Readings did reach the low 70s for a time, but has
dipped back into the upper 60s as clouds thickened a bit, at
least temporarily. Dew point values have been generally hanging
out in the mid 50s most of the day.

Winds have been light today for the most part, but have been
increasing a bit early this afternoon out of an easterly
direction. The speed has only been averaging at around 6mph for
the day so far, but closer to 10mph in the last hour or so. The
peak gust so far for the day is 20mph, which occurred just
before 12:30pm.

As noted, the visibility was very limited early this morning due
to the fog. But it has recovered nicely to around 40 miles by
early this afternoon.

The maximum temperature so far today is 71F degrees, which is 2
degrees below the normal high of 73F. The minimum temperature
since midnight is 55F degrees, which is 1 degree below the normal
low of 56F.

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Today’s Observations:

7 A.M.
Weather: Sky partially obscured, broken cirrus
Temperature: 57F; Dew Point: 57F; Relative Humidity: 100%
Wind: NNE @ 4 kts, wind light
Sea-level pressure: 1026.9 mb; 30.32 in. Hg: steady, then rising
Visibility: 1/4 mile, fog
6-hr Max temp: 59F
6-hr Min temp: 55F
24-hr Precip: 0.00 inches
BHO SA 1155 -X E250 BKN 1/4F 269/57/57/0304/032/ SUN DMLY VSBL
WND LGT/ 8/601 53009 10059 20055

10 A.M.
Weather: Broken cirrus, few stratocumulus distant all quadrants,
fog bank distant NNE-E
Temperature: 65F; Dew Point: 56F; Relative Humidity: 72%
Wind: ENE @ 6 kts, wind light
Sea-level pressure: 1027.1 mb; 30.33 in. Hg: rising, then falling
Visibility: 35 miles, 10 miles NNE-ENE, hazy
3-hr Precip: 0.00 inches
BHO SA 1455 E250 BKN 35 271/65/56/0706/033/ FEW SC DSNT ALQDS
F BNK DSNT NNE-E VSBY 10 NNE-ENE HAZY WND LGT/ 8/504 50002

1 P.M.
Weather: Scattered altocumulus, broken cirrus, broken cirrus,
few stratocumulus distant all quadrants, fog bank disant NNE-E
Temperature: 67F Dew Point: 54F; Relative Humidity: 62%
Wind: E @ 8G14 kts
Sea-level pressure: 1026.5 mb; 30.31 in. Hg: steady, then falling
Visibility: 40 miles, hazy
6-hr Max temp: 71F
6-hr Min temp: 57F
6-hr Precip: 0.00 inches
BHO SA 1755 150 SCT E220 BKN 250 BKN 40 265/67/54/0808G14/031/
FEW SC DSNT ALQDS F BNK DSNT NNE-E VSBY 12 NNE-ENE HAZY/ 8/554
58006 10071 20057

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SUMMARY FOR MONDAY, SEPTEMBER 15, 2025

TEMPERATURE (DEGREES F)
MAX…….72   NORMAL…..73
MIN…….57   NORMAL…..56
MEAN……65   NORMAL…..65

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL……………..0
TOTAL DEPARTURE FOR THE MONTH………………………-20 [-1.5 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY……………..0  DEPARTURE……..-3
TOTAL HEATING UNITS FOR THE MONTH…………….22  DEPARTURE……..-3
TOTAL HEATING UNITS FOR THE SEASON……………42  DEPARTURE……..-1
TOTAL HEATING UNITS LAST SEASON TO DATE……….21  DEPARTURE…….+21

COOLING DEGREE DAYS (SEASON JAN 2025 THRU DEC 2025)
TOTAL COOLING UNITS FOR YESTERDAY……………..0  DEPARTURE……..-2
TOTAL COOLING UNITS FOR THE MONTH…………….31  DEPARTURE…….-22
TOTAL COOLING UNITS FOR THE SEASON…………..703  DEPARTURE…….+54
TOTAL COOLING UNITS LAST SEASON TO DATE………741  DEPARTURE…….-38

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)………..20 N    @   06:17 A.M.
VECTOR #1 (1-Sec)……….19 N    @   06:17 A.M.
VECTOR #2 (1-Sec)……….18 N    @   05:58 A.M.
DAVIS #1……………….18 ENE  @   11:52 A.M.
DAVIS #2 ………………17 ENE  @   11:24 A.M.
RMY #1 (Instantaneous)…..18 ENE  @   11:52 A.M.
RMY #2 (Instantaneous)…..17 N    @   06:10 A.M.
MERLIN…………………17 ENE
RICHARDS (C5C) (Inst)……16 N    @   05:58 A.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………15 NNE  @   05:50 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..14 N    @   06:06 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..16 N    @   05:51 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………14 NNE  @   06:06 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………15 NNE  @   05:51 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..14 N    @   06:09 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..15 N    @   05:51 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………14 N    @   06:09 A.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………7.8 ENE [186 total miles] VECTOR #1……………….8.1
VECTOR #2……………….8.6
DAVIS #1………………..8.3 ENE
DAVIS #2………………..8.2 ENE
RMY #1………………….8.1 ENE
RMY #2………………….8.5 NE
RICHARDS (C5C)…………..8.6

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.13
TOTAL PRECIPITATION FOR THE MONTH…………..2.14 DEPARTURE…..+0.31
TOTAL PRECIPITATION FOR THE YEAR (2025)…….33.47 DEPARTURE…..-2.97

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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/+1/0.00/694/89            26 SSW VEC1 27 SSW RMY 28
9/5   82/63/73/+5/0.12/404/52            30 SSW VEC1 31 SSW RMY 33
9/6   84/64/74/+6/1.05/457/59            55 W   VEC1 55 W   RMY 57 TSTM
9/7   64/56/60/-7/0.97/000/00            16 WNW VEC1 16 NNE RMY 15
9/8   68/49/59/-8/0.00/508/66            21 NW  VEC1 21 NW  RMY 24
9/9   70/53/62/-5/0.00/697/91            22 ENE VEC1 23 E   RMY 23
9/10  65/54/60/-6/0.00/183/24            24 NE  VEC1 25 NE  RMY 25
9/11  77/51/64/-2/0.00/714/94            21 N   VEC1 17 N   RMY 18
9/12  71/56/64/-2/0.00/735/97            24 ENE VEC1 24 NNE RMY 23
9/13  76/55/66/+1/T/634/84               26 S   VEC1 26 S   RMY 25
9/14  79/57/68/+3/0.00/…/..            15 NE  VEC1 15 SW  RMY 15
9/15  72/57/65/0/0.00/…/..             20 N   VEC1 19 N   RMY 18

9/16 The low since midnight is 55F, the daily normal low is 56F.

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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 16
HIGH 91F IN 1939,1941
LOW 39F IN 1984
PRECIP 5.12 INCHES IN 1933 (Hurricane)
PEAK GUST 59 MPH SSE IN 1999

RECORDS FOR SEPTEMBER 17
HIGH 87F IN 2015
LOW 38F IN 1959
PRECIP 2.73 INCHES IN 1933
PEAK GUST 60 MPH WNW IN 1999

TODAY’S REPORT PREPARED BY: Matt Douglas