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Thursday, September 17, 2026

September 17, 2026

BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA THURSDAY, SEPTEMBER 17, 2026 ALL TIMES ARE…

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

THURSDAY, SEPTEMBER 17, 2026
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0526E
SUNSET:  1750E

A TASTE OF SUMMER RETURNS WITH WARM TEMPERATURES AND INCREASING
HUMIDITY….

Mother nature has turned the summer switch back on as we return
to warm temperatures and rather high humidity levels, especially
compared to recent conditions. We started the day with plenty
of sunshine, but clouds have been filling in the sky as the day
has progressed. The increase in clouds is due to a couple of
different processes. 1) the increasing low-level cumulus field
is due to the convective process along with increased low level
moisture. 2) the mid and high level clouds are spreading in
ahead of a cold frontal system that will cross the region tonight
and early tomorrow.

Temperatures started the day on the “warm” side with the low
this morning in the low to mid 60s (which is decently above
normal for this time of year). With plenty of sun through the
morning into early this afternoon, readings warmed quickly
through the 70s and into the lower 80s by early this afternoon.
As the warmer and more humid air mass is advected into the
region ahead of the front, dew point values have also been on
the increase throughout the day, reaching near 70F by early this
afternoon! This is rather unpleasant at any time of year, much
less in mid September.

Winds have generally been on the light side today, although it
has been showing signs of picking up a bit early this afternoon.
A variable wind has finally settled out of a southerly direction.
The average speed for the day so far is only around 6mph. The
peak gust for the day so far is 18mph, which occurred just after
11am this morning.

Visibility has been limited all day due to haziness. The view has
generally been held between 30-35 miles.

The maximum temperature so far today is 82F, which is 10 degrees
above the normal high of 72F. The minimum temperature since
midnight is 63F, which is 8 degrees above the normal low of 55F.

————————————————————–

Today’s Observations:

7 A.M.
Weather: Clear, few altocumulus distant SSW-W-N, few cirrus
distant WSW-N-NE
Temperature: 67F; Dew Point: 64F; Relative Humidity: 92%
Wind: S @ 2 kts, wind light
Sea-level pressure: 1025.5 mb; 30.28 in. Hg: rising, then falling
Visibility: 30 miles, hazy
6-hr Max temp: 67F
6-hr Min temp: 63F
24-hr Precip: 0.00 inches
BHO SA 1155 CLR 30 255/67/64/1902/028/ FEW AC DSNT SSW-W-N
FEW CI DSNT WSW-N-NE HAZY WND LGT/ 8/051 55001 10067 20063

10 A.M.
Weather: Broken cirrus, few cumulus all quadrants, few altocumulus
distant W-NNE
Temperature: 78F; Dew Point: 65F; Relative Humidity: 65%
Wind: S @ 6 kts, wind light and variable
Sea-level pressure: 1025.0 mb; 30.27 in. Hg: falling unsteadily
Visibility: 35 miles, hazy
3-hr Precip: 0.00 inches
BHO SA 1455 E250 BKN 30 250/78/65/1806/027/ FEW CU ALQDS
FEW AC DSNT W-NNE HAZY WND L/V/ 8/251 57005

1 P.M.
Weather: Broken cumulus, broken altocumulus, broken cirrus
Temperature: 81F; Dew Point: 69F; Relative Humidity: 65%
Wind: S @ 7 kts
Sea-level pressure: 1022.4 mb; 30.19 in. Hg: falling, then more rapidly
Visibility: 30 miles, hazy
6-hr Max temp: 81F
6-hr Min temp: 67F
6-hr Precip: 0.00 inches
BHO SA 1755 E30 BKN 60 BKN 250 BKN 30 224/81/69/1907/019/ HAZY/
8/251 58026 10081 20067

————————————————————–

SUMMARY FOR WEDNESDAY, SEPTEMBER 16, 2026

TEMPERATURE (DEGREES F)
MAX…….78   NORMAL…..73
MIN…….53   NORMAL…..56
MEAN……66   NORMAL…..64

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….+2
TOTAL DEPARTURE FOR THE MONTH (SEP)………………….-5 [-0.5 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2026 THRU JUN 2027)
TOTAL HEATING UNITS FOR YESTERDAY……………..0  DEPARTURE……..-3
TOTAL HEATING UNITS FOR THE MONTH (SEP)……….16  DEPARTURE…….-12
TOTAL HEATING UNITS FOR THE SEASON……………19  DEPARTURE…….-27
TOTAL HEATING UNITS LAST SEASON TO DATE……….44  DEPARTURE…….-25

COOLING DEGREE DAYS (SEASON: JAN 2026 THRU DEC 2026)
TOTAL COOLING UNITS FOR YESTERDAY……………..1  DEPARTURE……..-1
TOTAL COOLING UNITS FOR THE MONTH (SEP)……….39  DEPARTURE…….-17
TOTAL COOLING UNITS FOR THE SEASON…………..793  DEPARTURE……+142
TOTAL COOLING UNITS LAST SEASON TO DATE………703  DEPARTURE…….+90

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)………..21 SW   @   09:20 A.M.*
VECTOR #1 (1-Sec)……….21 WSW  @   09:21 A.M.
VECTOR #2 (1-Sec)……….21 SW   @   09:34 A.M.
DAVIS #1……………….21 S    @   10:08 A.M.
DAVIS #2 ………………21 S    @   05:20 P.M.
RMY #1 (Instantaneous)…..21 SW   @   09:20 A.M.
RMY #2 (Instantaneous)…..21 SW   @   06:44 A.M.
MERLIN…………………19 SW
RICHARDS (C5C) (Inst)……23 SW   @   09:20 A.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………13 SSW  @   12:50 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..15 WSW  @   09:21 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..16 SW   @   09:21 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………15 SW   @   09:21 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………15 WSW  @   09:21 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..15 WSW  @   09:21 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..16 SW   @   09:21 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………15 WSW  @   09:22 A.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL……..9.0 SW [217 total miles] VECTOR #1………………9.9
VECTOR #2……………..10.2
DAVIS #1……………….9.7 SW
DAVIS #2……………….9.8 SW
RMY #1…………………9.8 SW
RMY #2………………..10.2 SW
RICHARDS (C5C)………….9.5

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.14
TOTAL PRECIPITATION FOR THE MONTH (SEP)……..2.01 DEPARTURE…..+0.04
TOTAL PRECIPITATION FOR THE YEAR (2026)…….28.00 DEPARTURE…..-8.58

————————————————————–

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  69/57/63/-6/0.21/008/01             15 SSW VEC1 15 E   RMY 14
9/2  76/58/67/-2/0.00/393/50             21 ESE VEC1 21 ESE RMY 20
9/3  74/60/67/-1/0.45/196/25             24 SSE VEC1 24 SSE RMY 23
9/4  84/63/74/+6/0.00/624/80             24 NNW VEC1 25 NNW RMY 24
9/5  71/60/66/-2/T/412/53                24 ENE VEC1 24 ENE RMY 25
9/6  69/53/61/-7/0.35/364/47             24 NE  VEC1 24 NNE RMY 27
9/7  79/52/66/-1/0.00/732/95             30 NW  VEC1 30 NW  RMY 30
9/8  80/58/69/+2/0.00/546/71             23 WNW VEC1 22 NNW RMY 24
9/9  80/58/69/+2/0.02/130/17             36 SSW VEC1 36 SSW RMY 36
9/10 84/67/76/+10/T/641/84               44 W   VEC1 43 W   RMY 47
9/11 77/59/68/+2/0.00/654/86             23 NW  VEC1 23 NW  RMY 25
9/12 77/55/66/0/0.00/667/88              23 SSW VEC1 23 SSW RMY 22
9/13 67/60/64/-1/0.98/000/00             25 SE  VEC1 26 SE  RMY 24
9/14 72/53/63/-2/T/572/76                32 NNW VEC1 32 NNW RMY 34
9/15 68/48/58/-7/0.00/727/97             18 S   VEC1 18 SE  RMY 18
9/16 78/53/66/+2/0.00/522/70             21 SW  VEC1 21 WSW RMY 21

9/17 The low since midnight is 63F, the daily normal low is 55F.

————————————————————–

SEPTEMBER DAILY RECORDS TO DATE

NONE.

————————————————————–

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

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

RECORDS FOR SEPTEMBER 18
HIGH 88F IN 1906
LOW 36F IN 1919
PRECIP 4.25 INCHES IN 1996
PEAK GUST 77e MPH WNW IN 1948

TODAY’S REPORT PREPARED BY: Matt Douglas

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Blue Hill Observatory & Science Center · Legal

Data Use & Privacy Policy

Please read the full Policy before accessing Observatory data · Effective January 1, 2025

Notice: By accessing, downloading, or using any Blue Hill Observatory data or services, you unconditionally accept and agree to be bound by this Policy in its entirety. If you do not agree, you may not access or use Observatory data.
Effective January 1, 2025 · Milton, Massachusetts · bluehill.org
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