Tuesday, September 30, 2025

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

TUESDAY SEPTEMBER 30, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0541E
SUNSET:  1727E

FILTERED SUNSHINE THROUGH HIGH CIRRUS CLOUDS, COOLER AND BRISK….

High clouds continue to streak into the region as a frontal
system well to our south, interacting with both Hurricanes
Humberto and Imelda, continues to impact parts of the Mid
Atlantic and Southeastern U.S. Filtered sunshine has been getting
through the cloud deck, so all in all it’s been a rather nice
day with a brisk northeast flow developing.

Temperatures are cooler than they have been the past few days
with readings making it into the lower 70s. Dew point values in
spent most of the day in the low to mid 50s, but have climbed
into the upper 50s by the 1pm observation. Despite the rise, it
still feels quite comfortable for any outdoor activities.

The wind was generally on the light side during the wee hours
of the morning, then began to freshen by around 8am as it
shifted from a northwesterly direction to northeasterly. It
has gotten a bit gusty at times by late this morning. The average
speed for the day so far is around 11mph. The peak gust so far is
24mph, which occurred just before 10am this morning.

Visibility has decreased a bit from early this morning when it
was around 50 miles, to around 40 miles by late this morning and
early this afternoon.

The maximum temperature so far today is 71F degrees, which is
4 degrees above the normal high of 67F. The minimum temperature
since midnight is 59F degrees, which is 9 degrees above the
normal low of 50F.

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Today’s Observations:

7 A.M.
Weather: Overcast cirrus, thin spots in overcast all quadrants
Temperature: 61F; Dew Point: 51F; Relative Humidity: 69%
Wind: NNW @ 9 kts
Sea-level pressure: 1020.1 mb; 30.12 in. Hg: rising unsteadily
Visibility: 50 miles
6-hr Max temp: 61F
6-hr Min temp: 59F
24-hr Precip: 0.00 inches
BHO SA 1155 E250 OVC 50 201/61/51/3409/012/ THN SPTS IOVC ALQDS
SUN DMLY VSBL/ 8/004 52006 10061 20059

10 A.M.
Weather: Broken cirrus
Temperature: 69F; Dew Point: 52F; Relative Humidity: 55%
Wind: NE @ 12G21 kts
Sea-level pressure: 1020.6 mb; 30.14 in. Hg: rising, then falling
Visibility: 40 miles
3-hr Precip: 0.00 inches
BHO SA 1455 E250 BKN 40 206/69/52/0512G21/014/ 8/002 50005

1 P.M.
Weather: Thin broken cirrus
Temperature: 70F Dew Point: 58F; Relative Humidity: 65%
Wind: ENE @ 10G18 kts
Sea-level pressure: 1020.0 mb; 30.12 in. Hg: rising, then falling
Visibility: 40 miles, hazy
6-hr Max temp: 71F
6-hr Min temp: 61F
6-hr Precip: 0.00 inches
BHO SA 1755 E250 -BKN 40 200/70/58/0710G18/012/ HAZY/ 8/001
58006 10071 20061

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SUMMARY FOR MONDAY, SEPTEMBER 29, 2025

TEMPERATURE (DEGREES F)
MAX…….78   NORMAL…..68
MIN…….58   NORMAL…..51
MEAN……68   NORMAL…..59

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….+9
TOTAL DEPARTURE FOR THE MONTH………………………+41 [+1.2 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY……………..0  DEPARTURE……..-7
TOTAL HEATING UNITS FOR THE MONTH…………….41  DEPARTURE…….-52
TOTAL HEATING UNITS FOR THE SEASON……………61  DEPARTURE…….-50
TOTAL HEATING UNITS LAST SEASON TO DATE……….68  DEPARTURE……..-7

COOLING DEGREE DAYS (SEASON JAN 2025 THRU DEC 2025)
TOTAL COOLING UNITS FOR YESTERDAY……………..3  DEPARTURE……..+2
TOTAL COOLING UNITS FOR THE MONTH…………….64  DEPARTURE…….-10
TOTAL COOLING UNITS FOR THE SEASON…………..736  DEPARTURE…….+67
TOTAL COOLING UNITS LAST SEASON TO DATE………757  DEPARTURE…….-21

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)………..18 W    @   09:42 P.M.*
VECTOR #1 (1-Sec)……….18 N    @   12:14 A.M.
VECTOR #2 (1-Sec)……….19 N    @   12:48 P.M.
DAVIS #1……………….18 W    @   09:35 P.M.
DAVIS #2 ………………19 W    @   09:37 P.M.
RMY #1 (Instantaneous)…..18 N    @   12:42 A.M.
RMY #2 (Instantaneous)…..20 W    @   09:37 P.M.
MERLIN…………………17 W
RICHARDS (C5C) (Inst)……18 N    @   12:14 A.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………15 W    @   09:40 P.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..15 W    @   09:42 P.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..15 W    @   09:34 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………15 W    @   09:42 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………14 W    @   09:34 P.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..14 W    @   09:42 P.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..15 W    @   09:34 P.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………14 W    @   09:42 P.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………7.5 N [180 total miles] VECTOR #1……………….8.1
VECTOR #2……………….8.4
DAVIS #1………………..7.8 WNW
DAVIS #2………………..7.8 WNW
RMY #1………………….7.9 WNW
RMY #2………………….8.3 W
RICHARDS (C5C)…………..8.0

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.15
TOTAL PRECIPITATION FOR THE MONTH…………..4.49 DEPARTURE…..+0.59
TOTAL PRECIPITATION FOR THE YEAR (2025)…….35.82 DEPARTURE…..-2.69

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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/-4/0.00/705/96            20 SE  VEC1 19 SE  RMY 18
9/21  68/52/60/-2/0.00/593/81            18 ESE VEC1 19 SE  RMY 19
9/22  73/53/63/+1/0.00/620/85            20 SSW VEC1 20 SW  RMY 21
9/23  78/57/68/+6/0.00/305/42            25 SW  VEC1 25 SW  RMY 26
9/24  64/61/63/+2/0.19/000/00            21 E   VEC1 21 E   RMY 22
9/25  70/62/66/+5/1.67/000/00            35 SSW VEC1 35 SSW RMY 35 TSTM
9/26  80/63/72/+12/0.00/625/87           24 NW  VEC1 23 WNW RMY 27
9/27  80/59/70/+10/0.00/443/62           20 S   VEC1 20 S   RMY 18
9/28  81/63/72/+13/0.05/534/75           22 N   VEC1 22 N   RMY 22
9/29  78/58/68/+9/0.00/604/85            18 W   VEC1 18 N   RMY 18

9/30 The low since midnight is 59F, the daily normal low is 50F.

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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 30
HIGH 84F IN 1986
LOW 31F IN 1992
PRECIP 2.44 INCHES IN 2015
PEAK GUST 71 MPH S IN 2020

RECORDS FOR OCTOBER 1
HIGH 85F IN 1927
LOW 30F IN 1992
PRECIP 1.63 INCHES IN 2014
PEAK GUST 68e MPH SSE IN 1977

TODAY’S REPORT PREPARED BY: Matt Douglas