Tuesday, September 23, 2025

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

TUESDAY, SEPTEMBER 23, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0533E
SUNSET:  1739E

WARMER AND MORE HUMID TODAY WITH INCREASING CLOUDS….

We started the day with fog early this morning, but it quickly
burned off giving us a period of sunshine through the mid
morning period. Thereafter mid and high level clouds began
to stream into the area filtering the sunshine late this
morning, but a deck of lower clouds have since overspread
the area drastically limiting the sun by the 1pm observation.

Temperatures are warmer today, with readings reaching the
upper 70s by early this afternoon. With the dew point rising
into the mid 60s, it does feel quite a bit more humid today,
giving us a little taste of summer on this first full day of
astronomical fall.

The wind has been fairly steady out of the southwest and west-
southwest. The average speed for the day so far is around 12mph.
The peak gust is 24mph so far, which occurred just after 11:30am
this morning.

Visibility has improved since early this morning, but overall
is still limited by hazy conditions. The view was as low as 1/8th
of a mile for a time very early this morning during the fog, but
has recovered to around 30 miles for the balance of the day.

The maximum temperature so far today is 78F degrees, which is
8 degrees above the normal high of 70F. The minimum temperature
since midnight is 57F degrees, which is 4 degrees above the
normal low of 53F.

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Today’s Observations:

7 A.M.
Weather: Broken stratus fractus, thin broken cirrus
Temperature: 61F; Dew Point: 60F; Relative Humidity: 96%
Wind: SW @ 9 kts
Sea-level pressure: 1017.2 mb; 30.04 in. Hg: rising, then more rapidly
Visibility: 12 miles, thin fog
6-hr Max temp: 61F
6-hr Min temp: 57F
24-hr Precip: 0.00 inches
BHO SA 1155 E1 BKN 250 -BKN 12 172/61/60/2209/004/ THN F ALQDS/
8/601 53007 10061 20057

10 A.M.
Weather: Broken altocumulus, broken cirrostratus, few small cumulus
all quadrants
Temperature: 71F; Dew Point: 64F; Relative Humidity: 76%
Wind: WSW @ 8G15 kts
Sea-level pressure: 1017.0 mb; 30.03 in. Hg: steady, then falling
Visibility: 30 miles, hazy
3-hr Precip: 0.00 inches
BHO SA 1455 E100 BKN 200 BKN 30 170/71/64/2408G15/003/
FEW SML CU ALQDS HAZY/ 8/156 58002

1 P.M.
Weather: Broken stratocumulus, broken altocumulus, broken cirrus
Temperature: 77F Dew Point: 66F; Relative Humidity: 69%
Wind: SW @ 9G18 kts
Sea-level pressure: 1015.1 mb; 29.98 in. Hg: falling, then more rapidly
Visibility: 30 miles, hazy
6-hr Max temp: 78F
6-hr Min temp: 61F
6-hr Precip: 0.00 inches
BHO SA 1755 E25 BKN 120 BKN 250 BKN 30 151/77/66/2309G18/998/
HAZY/ 8/551 58019 10078 20061

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SUMMARY FOR MONDAY, SEPTEMBER 22, 2025

TEMPERATURE (DEGREES F)
MAX…….73   NORMAL…..70
MIN…….53   NORMAL…..53
MEAN……63   NORMAL…..62

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….+1
TOTAL DEPARTURE FOR THE MONTH………………………-16 [-0.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY……………..2  DEPARTURE……..-3
TOTAL HEATING UNITS FOR THE MONTH…………….39  DEPARTURE…….-13
TOTAL HEATING UNITS FOR THE SEASON……………59  DEPARTURE…….-11
TOTAL HEATING UNITS LAST SEASON TO DATE……….39  DEPARTURE…….+20

COOLING DEGREE DAYS (SEASON JAN 2025 THRU DEC 2025)
TOTAL COOLING UNITS FOR YESTERDAY……………..0  DEPARTURE……..-2
TOTAL COOLING UNITS FOR THE MONTH…………….38  DEPARTURE…….-28
TOTAL COOLING UNITS FOR THE SEASON…………..710  DEPARTURE…….+48
TOTAL COOLING UNITS LAST SEASON TO DATE………753  DEPARTURE…….-43

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 SSW  @   05:40 P.M.
VECTOR #1 (1-Sec)……….20 SW   @   11:28 P.M.
VECTOR #2 (1-Sec)……….20 SWE  @   11:09 P.M.
DAVIS #1……………….20 S    @   05:39 P.M.
DAVIS #2 ………………24 S    @   05:40 P.M.
RMY #1 (Instantaneous)…..21 SW   @   11:28 P.M.
RMY #2 (Instantaneous)…..20 SW   @   11:07 P.M.
MERLIN…………………19 WSW
RICHARDS (C5C) (Inst)……21 SW   @   11:28 P.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………16 SW   @   11:17 P.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..15 SW   @   11:09 P.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..15 SW   @   11:09 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………14 SW   @   11:09 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………16 S    @   05:41 P.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..15 SW   @   10:56 P.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..15 SW   @   11:09 P.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………14 SSW  @   05:41 P.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………7.3 SSW [176 total miles] VECTOR #1……………….7.9
VECTOR #2……………….8.2
DAVIS #1………………..7.3 S
DAVIS #2………………..7.7 SSW
RMY #1………………….7.7 S
RMY #2………………….8.3 S
RICHARDS (C5C)…………..7.9

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.15
TOTAL PRECIPITATION FOR THE MONTH…………..2.58 DEPARTURE…..-0.28
TOTAL PRECIPITATION FOR THE YEAR (2025)…….33.91 DEPARTURE…..-3.56

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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/+3/0.00/572/76            15 NE  VEC1 15 SW  RMY 15
9/15  72/57/65/0/0.00/689/92             20 N   VEC1 19 N   RMY 18
9/16  71/55/63/-1/0.00/403/54            20 E   VEC1 19 ESE RMY 19
9/17  71/55/63/-1/T/424/57               22 E   VEC1 22 E   RMY 21
9/18  75/61/68/+5/0.44/252/34            20 S   VEC1 20 S   RMY 20 TSTM
9/19  80/57/69/+6/0.00/715/97            24 N   VEC1 24 N   RMY 23
9/20  67/51/59/-4/0.00/…/..            20 SE  VEC1 19 SE  RMY 18
9/21  68/52/60/-2/0.00/…/..            18 ESE VEC1 19 SE  RMY 19
9/22  73/53/63/+1/0.00/…/..            20 SSW VEC1 20 SW  RMY 21

9/23 The low since midnight is 57F, the daily normal low is 53F.

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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 23
HIGH 93F IN 1895,1914
LOW 33F IN 1904
PRECIP 2.67 INCHES IN 1994
PEAK GUST 62 MPH SSW IN 1989

RECORDS FOR SEPTEMBER 24
HIGH 87F IN 1959
LOW 33F IN 1885,1950,1963
PRECIP 1.19 INCHES IN 1955
PEAK GUST 54e MPH SW IN 1940

TODAY’S REPORT PREPARED BY: Matt Douglas