Saturday, September 13, 2025
BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
SATURDAY, SEPTEMBER 13, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0522E
SUNSET: 1757E
A BIT WARMER WITH A MIX OF SUN AND CLOUDS….
This morning began with some fog here on Blue Hill, which quickly
dissipated following sunrise. Skies were initially mostly clear with
just some scattered cirrus. Cumulus began developing around 10am,
increasing in coverage through the early afternoon.
The low temperature this morning was in the mid 50s, rising to the
mid 70s by the final observation. With the flow now out of the south,
the dew point has been creeping up today, reaching the upper 50s by
the afternoon.
Winds are on the light side, with an average speed of only 7mph. The
prevailing direction so far is out of the south-southwest. The peak
gust occurred around 12:30pm, with a speed of 17mph.
Visibility has held steady at 40 miles all day, likely limited by the
moisture in the air.
The maximum temperature so far today is 76F degrees, which is 2
degrees above the normal high of 74F. The minimum temperature
since midnight is 55F degrees, which is 2 degrees below the normal
low of 57F.
————————————————————–
Today’s Observations:
7 A.M.
Weather: Scattered cirrus, few altocumulus distant W-N
Temperature: 60F; Dew Point: 54F; Relative Humidity: 81%
Wind: SSW @ 5 kts, wind light
Sea-level pressure: 1022.7 mb; 30.20 in. Hg: falling, then rising
Visibility: 40 miles
6-hr Max temp: 60F
6-hr Min temp: 55F
24-hr Precip: 0.00 inches
BHO SA 1155 250 SCT 40 227/60/54/2005/020/ FEW AC DSNT W-N WND LGT/
8/051 53002 10060 20055
10 A.M.
Weather: Scattered cirrus, few small cumulus all quadrants
Temperature: 69F; Dew Point: 56F; Relative Humidity: 62%
Wind: SSW @ 5 kts, wind light
Sea-level pressure: 1021.6 mb; 30.17 in. Hg: falling, then more rapidly
Visibility: 40 miles
3-hr Precip: 0.00 inches
BHO SA 1455 250 SCT 40 216/69/56/2005/017/ FEW SML CU ALQDS WND LGT/
8/101 58011
1 P.M.
Weather: Broken cumulus, broken cirrus
Temperature: 76F Dew Point: 58F; Relative Humidity: 54%
Wind: SW @ 7 kts
Sea-level pressure: 1019.6 mb; 30.11 in. Hg: falling unsteadily
Visibility: 40 miles
6-hr Max temp: 76F
6-hr Min temp: 60F
6-hr Precip: 0.00 inches
BHO SA 1755 E40 BKN 250 BKN 40 196/76/58/2207/011/ 8/201 57020
10076 20060
————————————————————–
SUMMARY FOR FRIDAY, SEPTEMBER 12, 2025
TEMPERATURE (DEGREES F)
MAX…….71 NORMAL…..74
MIN…….56 NORMAL…..57
MEAN……64 NORMAL…..66
DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….-2
TOTAL DEPARTURE FOR THE MONTH………………………-24 [-2.2 DEGREES/DAY]
HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY……………..1 DEPARTURE……..-1
TOTAL HEATING UNITS FOR THE MONTH…………….22 DEPARTURE……..+5
TOTAL HEATING UNITS FOR THE SEASON……………42 DEPARTURE……..+6
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……..-3
TOTAL COOLING UNITS FOR THE MONTH…………….27 DEPARTURE…….-19
TOTAL COOLING UNITS FOR THE SEASON…………..699 DEPARTURE…….+57
TOTAL COOLING UNITS LAST SEASON TO DATE………724 DEPARTURE…….-25
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)………..24 ENE @ 09:02 A.M.
VECTOR #1 (1-Sec)……….24 NNE @ 01:25 A.M.
VECTOR #2 (1-Sec)……….24 NNE @ 07:19 A.M.
DAVIS #1……………….22 ENE @ 08:37 A.M.
DAVIS #2 ………………22 NE @ 07:04 A.M.
RMY #1 (Instantaneous)…..23 ENE @ 09:02 A.M.
RMY #2 (Instantaneous)…..24 NNE @ 07:19 A.M.
MERLIN………………….M
RICHARDS (C5C) (Inst)……21 @ 09:02 A.M.
FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………15 ENE @ 08:49 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..16 @ 07:19 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..16 @ 07:19 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………16 ENE @ 08:49 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………16 NE @ 07:19 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..15 NE @ 08:48 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..16 NNE @ 07:19 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………15 @ 08:48 A.M.
AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………9.8 ENE [236 total miles]
VECTOR #1……………….9.9
VECTOR #2………………10.6
DAVIS #1……………….10.2 ENE
DAVIS #2……………….10.3 E
RMY #1………………….9.7 ENE
RMY #2…………………10.5 ENE
RICHARDS (C5C)………….10.2
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…..+0.70
TOTAL PRECIPITATION FOR THE YEAR (2025)…….33.47 DEPARTURE…..-2.58
————————————————————–
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 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/…/.. 26 SSW VEC1 27 SSW RMY 28
9/5 82/63/73/+5/0.12/…/.. 30 SSW VEC1 31 SSW RMY 33
9/6 84/64/74/+6/1.05/…/.. 55 W VEC1 55 W RMY 57 TSTM
9/7 64/56/60/-7/0.97/…/.. 16 WNW VEC1 16 NNE RMY 15
9/8 68/49/59/-8/0.00/…/.. 21 NW VEC1 21 NW RMY 24
9/9 70/53/62/-5/0.00/…/.. 22 ENE VEC1 23 E RMY 23
9/10 65/54/60/-6/0.00/…/.. 24 NE VEC1 25 NE RMY 25
9/11 77/51/64/-2/0.00/…/.. 21 N VEC1 17 N RMY 18
9/12 71/56/64/-2/0.00/…/.. 24 ENE VEC1 24 NNE RMY 23
9/13 The low since midnight is 55F, the daily normal low is 57F.
————————————————————–
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 13
HIGH 91F IN 1957
LOW 40F IN 1985
PRECIP 3.10 INCHES IN 1987
PEAK GUST 44 MPH WNW IN 1986
RECORDS FOR SEPTEMBER 14
HIGH 90F IN 1931
LOW 34F IN 1911
PRECIP 2.90 INCHES IN 1944 (Great Atlantic Hurricane in 1944)
PEAK GUST 96e MPH E IN 1944 (Great Atlantic Hurricane in 1944)
TODAY’S REPORT PREPARED BY: Joshua Polen
