Thursday, July 17, 2025
BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA
THURSDAY, JULY 17, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0423E
SUNSET: 1918E
EARLY FOG BURNS OFF TO PARTIAL SUNSHINE; ONCE AGAIN HOT AND HUMID
BUT JUST MISSING OUT ON OUR SECOND OFFICIAL HEATWAVE OF THE SEASON….
We started the day once again with low clouds and fog. The fog
lifted pretty quickly this morning, but a lot of clouds have stuck
around giving us generally a mix of sun and clouds for the day.
The temperature reached just short of 90F (89.3F) today, as such
we have not reached the criteria of 3 consecutive days of 90F, thus
to this point, we have avoided our second official heatwave of the
season here on the summit. Dew point values were holding steady in
the mid 70s all morning, but have dropped a bit to the low 70s
thanks to some mixing from aloft. Heat index values did push into
the mid and upper 90s for a time late this morning, but have eased
back to the low 90s for the time being.
The one saving grace today is the wind. We’re finally seeing a day
with something other than light speed. A south-southwest to
southwest breeze has been gradually increasing through the morning
into early this afternoon. The average speed for the day so far is
around 13mph. Gusts have been ramping up getting above 30mph at
times. The peak gust so far is 38mph, which occurred right around
12:30pm.
Visibility has been limited today, first by fog early this morning,
then by haziness the rest of the day. The view improved to around
35-40 miles at most by early afternoon.
The maximum temperature so far today is 89F degrees, which is
7 degrees above the normal high of 82F. The minimum temperature
since midnight is 73F degrees, which is 9 degrees above the normal
low of 64F.
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Today’s Observations:
7 A.M.
Weather: Overcast stratocumulus, few breaks in overcast all quadrants
Temperature: 78F; Dew Point: 76F; Relative Humidity: 92%
Wind: SSW @ 8 kts
Sea-level pressure: 1013.1 mb; 29.92 in. Hg: falling, then rising
Visibility: 12 miles, thin fog
6-hr Max temp: 78F
6-hr Min temp: 73F
24-hr Precip: 0.00 inches
BHO SA 1155 E3 OVC 12 131/78/76/2108/992/ FEW BINOVC ALQDS
THN F ALQDS/ 8/5// 55002 10078 20073
10 A.M.
Weather: Broken cumulus, broken altocumulus, thin broken cirrus
Temperature: 85F; Dew Point: 76F; Relative Humidity: 73%
Wind: SW @ 13G21 kts
Sea-level pressure: 1011.3 mb; 29.86 in. Hg: falling, then more slowly
Visibility: 25 miles, hazy
3-hr Precip: 0.00 inches
BHO SA 1455 E22 BKN 150 BKN 250 -BKN 25 113/85/76/2213G21/986/
HAZY/ 8/251 56018
1 P.M.
Weather: Broken altocumulus/castellanus, broken dense cirrus,
thin broken cirrus
Temperature: 85F Dew Point: 71F; Relative Humidity: 62%
Wind: SW @ 17G28 kts, peak wind SW 38mph at 12:31 P.M.
Sea-level pressure: 1009.9 mb; 29.82 in. Hg: falling, then more slowly
Visibility: 40 miles, hazy
6-hr Max temp: 89F
6-hr Min temp: 78F
6-hr Precip: 0.00 inches
BHO SA 1755 E100 BKN 180 BKN 250 BKN 40 099/85/75/2217G28/982/
FEW CU ALQDS FEW AS ALQDS HAZY PK WND 2233/31/ 8/273 56014
10089 20078
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SUMMARY FOR WEDNESDAY, JULY 16, 2025
TEMPERATURE (DEGREES F); R = RECORD VALUE
MAX…….93 NORMAL…..82
MIN…….71R NORMAL…..64
MEAN……82 NORMAL…..73
DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….+9
TOTAL DEPARTURE FOR THE MONTH………………………+45 [+2.6 DEGREES/DAY]
HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY……………..0 DEPARTURE………0
TOTAL HEATING UNITS FOR THE MONTH……………..1 DEPARTURE……..-3
TOTAL HEATING UNITS FOR THE SEASON…………….1 DEPARTURE……..-3
TOTAL HEATING UNITS LAST SEASON TO DATE………..0 DEPARTURE……..+1
COOLING DEGREE DAYS (SEASON JAN 2025 THRU DEC 2025)
TOTAL COOLING UNITS FOR YESTERDAY…………….17 DEPARTURE……..+9
TOTAL COOLING UNITS FOR THE MONTH……………164 DEPARTURE…….+42
TOTAL COOLING UNITS FOR THE SEASON…………..364 DEPARTURE……+103
TOTAL COOLING UNITS LAST SEASON TO DATE………370 DEPARTURE……..-6
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)……….E24 SSW @ 03:21 P.M.
VECTOR #1 (1-Sec)……….24 SSW @ 03:21 P.M.
VECTOR #2 (1-Sec)……….24 SW @ 04:01 P.M.
DAVIS #1……………….25 S @ 03:50 P.M.
DAVIS #2 ………………27 S @ 03:42 P.M.
RMY #1 (Instantaneous)…..23 SSW @ 05:38 P.M.
RMY #2 (Instantaneous)…..25 SSW @ 03:21 P.M.
MERLIN…………………21 SW
RICHARDS (C5C) (Inst)…..OTS
FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………17 SSW @ 04:42 P.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..17 @ 04:43 P.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..19 @ 04:43 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………17 S @ 04:43 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………19 S @ 05:22 P.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..17 SSW @ 04:54 P.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..19 SSW @ 04:43 P.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE……..OTS
AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………8.6 SSW [206 total miles]
VECTOR #1……………….9.1
VECTOR #2……………….9.4
DAVIS #1………………..8.6 SSW
DAVIS #2………………..9.4 SSW
RMY #1………………….8.9 SSW
RMY #2………………….9.5 SW
RICHARDS (C5C)…………..OTS
PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.11
TOTAL PRECIPITATION FOR THE MONTH…………..5.20 DEPARTURE…..+3.41
TOTAL PRECIPITATION FOR THE YEAR (2025)…….28.43 DEPARTURE…..-0.59
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PRELIMINARY CLIMATE SUMMARY FOR JULY 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
7/1 90/68/79/+8/0.14/411/45 38 W VEC1 38 W RMY 41 TSTM
7/2 85/69/77/+6/0.02/247/27 23 WSW VEC1 24 WSW RMY 24
7/3 88/63/76/+4/0.03/748/82 39 SW VEC1 39 SW RMY 40 TSTM
7/4 80/60/70/-2/0.00/875/96 28 NNW VEC1 27 NNW RMY 29
7/5 83/61/72/0/0.00/664/73 23 W VEC1 23 W RMY 24
7/6 92/65/79/+7/0.00/818/90 29 SW VEC1 29 SW RMY 29
7/7 88/69/79/+7/0.01/490/54 28 SSW VEC1 28 SSW RMY 29 TSTM
7/8 94/67/81/+9/0.36/562/62 24 WSW VEC1 24 WSW RMY 27 TSTM
7/9 74/65/70/-3/0.73/172/19 26 SW VEC1 27 SW RMY 28 TSTM
7/10 66/61/64/-9/3.85/000/00 24 ENE VEC1 24 ENE RMY 24 TSTM
7/11 80/62/71/-2/0.00/190/21 18 SSW VEC1 18 SSW RMY 18
7/12 84/65/75/+2/0.00/505/56 20 S VEC1 20 S RMY 19
7/13 85/63/74/+1/0.00/505/56 21 SSW VEC1 21 SSW RMY 21
7/14 81/65/73/0/T/216/24 23 SW VEC1 23 SW RMY 25
7/15 90/71/81/+8/0.06/665/74 24 SSW VEC1 24 SSW RMY 24
7/16 93/71/82/+9/0.00/690/77 24 SSW VEC1 24 SSW RMY 23
7/17 The low since midnight is 73F, the daily normal low is 64F.
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JULY DAILY RECORDS TO DATE
7/10 RECORD HIGHEST PRECIPITATION OF 3.85 INCHES;
BEATING OLD RECORD OF 1.95 INCHES SET IN 2015
7/16 TIED RECORD HIGH MINIMUM TEMPERATURE OF 71F;
ALSO SET IN 1901, 1958, 1968, 2013, AND 2023
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DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated)
RECORDS FOR JULY 17
HIGH 96F IN 1999
LOW 47F IN 1892
PRECIP 1.39 INS IN 1989
WIND 46 MPH WNW IN 1971
RECORDS FOR JULY 18
HIGH 96F IN 1991, 1999
LOW 54F IN 1892, 1956, 1971
PRECIP 1.65 INS IN 2000
WIND 43e MPH SW IN 1949
TODAY’S REPORT PREPARED BY: MFD
