Monday, September 15, 2025
BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
MONDAY, SEPTEMBER 15, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0524E
SUNSET: 1753E
A MIX OF SUN AND CLOUDS WITH AN ONSHORE BREEZE AND COOLER
TEMPERATURES….
We started off with sunshine mixed with some high thin cirrus
clouds early this morning, but as the onshore flow freshened, a
stratus layer pushed down the coast and has spread over the area.
Thanks to the sun and somewhat drier air over the land, the
clouds did break up, so it’s created an interplay of sun and
clouds into early this afternoon of both stratucumulus and
cumulus.
Temperatures are cooler today thanks to the wind off the ocean.
Readings have reached the low 70s by early this afternoon. Dew
point values were a bit lower earlier this morning making for a
drier feel to the air than yesterday, but the dew point has since
risen back into the low 60s by late this morning into early this
afternoon. As such, there is a more humid feel out there this
afternoon.
Winds were quite light during the wee hours of the morning, but
freshened out of the north, then northeasterly by the 7am
observation. However, it has veered more easterly by early this
afternoon. The speed has been fairly steady since this morning,
averaging at around 8mph. The peak gust so far for the day is
20mph, which occurred just after 6:15am this morning.
Visibility has been limited today from haziness thanks to the high
humidity levels. The view decreased from around 35 miles early
this morning to only 20-25mph late this morning as the stratus
layer was moving in. It has rebounded back to around 35 miles
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 57F degrees, which is 1 degree above the normal
low of 56F.
————————————————————–
Today’s Observations:
7 A.M.
Weather: Thin broken cirrus, stratus layer distant NNW-NNE
Temperature: 60F; Dew Point: 57F; Relative Humidity: 89%
Wind: NNE @ 8G14 kts
Sea-level pressure: 1024.6 mb; 30.26 in. Hg: rising, then more rapidly
Visibility: 35 miles, hazy
6-hr Max temp: 63F
6-hr Min temp: 57F
24-hr Precip: 0.00 inches
BHO SA 1155 E250 -BKN 35 246/60/57/0308G14/026/ ST LYR DSNT
NNW-NNE HAZY/ 8/601 53013 10063 20057
10 A.M.
Weather: Broken stratocumulus, thin broken cirrus
Temperature: 68F; Dew Point: 61F; Relative Humidity: 78%
Wind: ENE @ 8 kts
Sea-level pressure: 1026.4 mb; 30.31 in. Hg: rising, then more rapidly
Visibility: 25 miles, hazy
3-hr Precip: 0.00 inches
BHO SA 1455 E10 BKN 250 -BKN 25 264/68/61/0708/031/ HAZY/
8/501 53018
1 P.M.
Weather: Scattered stratocumulus, scattered cumulus,
thin scattered cirrus
Temperature: 71F Dew Point: 62F; Relative Humidity: 72%
Wind: E @ 7 kts
Sea-level pressure: 1026.3 mb; 30.31 in. Hg: rising, then falling
Visibility: 35 miles, hazy
6-hr Max temp: 71F
6-hr Min temp: 60F
6-hr Precip: 0.00 inches
BHO SA 1755 20 SCT 25 SCT 250 -SCT 35 263/71/62/0807/031/ HAZY/
8/801 58001 10071 20060
————————————————————–
SUMMARY FOR SUNDAY, SEPTEMBER 14, 2025
TEMPERATURE (DEGREES F)
MAX…….79 NORMAL…..74
MIN…….57 NORMAL…..56
MEAN……68 NORMAL…..65
DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….+3
TOTAL DEPARTURE FOR THE MONTH………………………-20 [-1.6 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……..-1
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……………..3 DEPARTURE………0
TOTAL COOLING UNITS FOR THE MONTH…………….31 DEPARTURE…….-20
TOTAL COOLING UNITS FOR THE SEASON…………..703 DEPARTURE…….+56
TOTAL COOLING UNITS LAST SEASON TO DATE………737 DEPARTURE…….-34
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)………..15 NE @ 01:22 P.M.
VECTOR #1 (1-Sec)……….15 SW @ 12:38 A.M.
VECTOR #2 (1-Sec)……….15 SW @ 01:32 A.M.
DAVIS #1……………….15 SSW @ 12:34 A.M.
DAVIS #2 ………………15 WSW @ 12:39 A.M.
RMY #1 (Instantaneous)…..15 SW @ 12:36 A.M.
RMY #2 (Instantaneous)…..16 SW @ 01:32 A.M.
MERLIN………………….M
RICHARDS (C5C) (Inst)……16 SW @ 12:38 A.M.
FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………12 SW @ 01:18 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..12 SW @ 12:39 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..12 SW @ 12:37 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………12 SW @ 12:47 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………12 SW @ 01:33 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..12 SW @ 01:33 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..12 SW @ 12:37 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………12 WSW @ 01:50 A.M.
AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………6.0 NW [143 total miles]
VECTOR #1……………….6.7
VECTOR #2……………….6.8
DAVIS #1………………..6.4 SW
DAVIS #2………………..6.1 WSW
RMY #1………………….6.5 WSW
RMY #2………………….6.8 WSW
RICHARDS (C5C)…………..7.0
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…..+0.44
TOTAL PRECIPITATION FOR THE YEAR (2025)…….33.47 DEPARTURE…..-2.84
————————————————————–
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 The low since midnight is 57F, the daily normal low is 56F.
————————————————————–
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 15
HIGH 89F IN 1931
LOW 35F IN 1913
PRECIP 3.93 INCHES IN 1904 (Extra-tropical storm making landfall in New England on 9/15/1904 passing east of BHO and bringing a storm total of 4.11 inches 9/14-15/1904)
PEAK GUST 65e MPH NW IN 1944 (In the wake of Great Atlantic Hurricane)
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
TODAY’S REPORT PREPARED BY: Matt Douglas
