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Tuesday, May 20, 2025

May 20, 2025

BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA TUESDAY, MAY 20, 2025 ALL TIMES ARE…

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

TUESDAY, MAY 20, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0418E
SUNSET:  1904E

STORM OFFSHORE THROWS CLOUDS OUR WAY….

As a storm system sits and spins offshore to our east, cloudiness and
cool temperatures remain for a second day. Stratocumulus have filled
the sky since this morning, with only a few occasional breaks, primarily
to the west.

Flow out of the north has brought cooler temperatures. The low this morning
was in the mid 40s. With a lack of sunshine and cold advection, temperatures
have struggled to rise, only reaching the mid 50s by the afternoon. The dew
point has held in the low 40s. It is a bit chilly out there!

Yesterday was quite breezy, but wind speeds have slowed dramatically today.
The average so far is 11mph with a decreasing trend. As before mentioned, the
prevailing direction for the day is out of the north-northwest, but winds
became easterly as of noon time. The peak gust occurred this morning around
12:30am, with a speed of 29mph.

Visibility is great, with views extending up to 70 miles all day!

The maximum temperature for today is 55F degrees, which is 13 degrees
below the normal high of 68F. The minimum temperature since midnight
is 46F degrees, which is 3 degrees below the normal low.

————————————————————–

Today’s Observations:

7 A.M.
Weather: Broken stratocumulus
Temperature: 49F; Dew Point: 41F; Relative Humidity: 78%
Wind: NNW @ 09G16 kts
Sea-level pressure: 1011.6 mb; 29.87 in. Hg: rising, then more slowly
Visibility: 70 miles
6-hr Max temp: 49F
6-hr Min temp: 46F
24-hr Precip:  0.00 inches
24-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1155 E40 BKN 70 116/49/41/3309G16/987/ 8/500 51015 10049 20046

10 A.M.
Weather: Overcast stratocumulus
Temperature: 54F; Dew Point: 42F; Relative Humidity: 65%
Wind: NNW @ 8 kts
Sea-level pressure: 1013.1 mb; 29.92 in. Hg: rising unsteadily
Visibility: 70 miles
3-hr Precip:  0.00 inches
3-hr Snowfall: 0.0 inches
BHO SA 1455 E35 OVC 70 131/54/42/3408/992/ 8/5// 52015

1 P.M.
Weather: Overcast stratocumulus
Temperature: 54F Dew Point: 44F; Relative Humidity: 69%
Wind: E @ 6 kts, wind light
Sea-level pressure: 1014.5 mb; 29.96 in. Hg: rising unsteadily
Visibility: 70 miles
6-hr Max temp: 55F
6-hr Min temp: 49F
6-hr Precip:  0.00 inches
6-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1755 E35 OVC 70 145/54/44/0806/996/ WND LGT/ 8/5// 52014 10055 20049

————————————————————–

SUMMARY FOR MONDAY, MAY 19, 2025

TEMPERATURE (DEGREES F)
MAX…….63   NORMAL…..68
MIN…….46   NORMAL…..49
MEAN……55   NORMAL…..58

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….-3
TOTAL DEPARTURE FOR THE MONTH………………………+81 [+4.1 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2024 THRU JUN 2025)
TOTAL HEATING UNITS FOR YESTERDAY…………….10  DEPARTURE……..+2
TOTAL HEATING UNITS FOR THE MONTH……………102  DEPARTURE…….-81
TOTAL HEATING UNITS FOR THE SEASON………….5500  DEPARTURE……-570
TOTAL HEATING UNITS LAST SEASON TO DATE……..5357  DEPARTURE……+143

COOLING DEGREE DAYS (SEASON JAN 2025 THRU DEC 2025)
TOTAL COOLING UNITS FOR YESTERDAY……………..0  DEPARTURE……..-1
TOTAL COOLING UNITS FOR THE MONTH…………….11  DEPARTURE……..+1
TOTAL COOLING UNITS FOR THE SEASON……………14  DEPARTURE……..+1
TOTAL COOLING UNITS LAST SEASON TO DATE………..2  DEPARTURE…….+12

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)………..41 NW   @   08:15 A.M.
VECTOR #1 (1-Sec)……….42 NW   @   04:09 A.M.
VECTOR #2 (1-Sec)……….45 WNW  @   04:09 A.M.
DAVIS #1……………….40 WNW  @   04:05 A.M.
DAVIS #2 ………………40 NW   @   04:07 A.M.
RMY #1 (Instantaneous)…..44 NW   @   04:06 A.M.
RMY #2 (Instantaneous)…..46 WNW  @   04:09 A.M.
MERLIN…………………38 NW
RICHARDS (C5C) (Inst)…..OTS

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………29 NW   @   04:08 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..28      @   05:08 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..32      @   04:07 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………30 WNW  @   04:07 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………31 NW   @   04:07 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..28 NW   @   05:08 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..31 WNW  @   04:07 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE……..OTS

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL……..18.2 NW [437 total miles] VECTOR #1………………17.1
VECTOR #2………………18.1
DAVIS #1……………….17.7 NW
DAVIS #2……………….17.6 NNW
RMY #1…………………16.6 NW
RMY #2…………………17.4 NW
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…………..3.34 DEPARTURE…..+1.08
TOTAL PRECIPITATION FOR THE YEAR (2025)…….17.46 DEPARTURE…..-3.58

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..0.0 DEPARTURE…….0.0
TOTAL SNOWFALL FOR THE MONTH………………..0.0 DEPARTURE…….0.0
TOTAL SNOWFALL FOR THE SEASON (2024-2025)……35.8 DEPARTURE…..-33.9

————————————————————–

PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/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

5/1   69/43/56/+3/0.00/0.0/744/88        28 S   VEC1 28 SSW RMY 28
5/2   79/47/63/+9/0.19/0.0/339/40        28 SE  VEC1 29 SE  RMY 25 TSTM
5/3   84/54/69/+15/0.15/0.0/561/66       43 SSW VEC1 42 SSW RMY 44 TSTM
5/4   77/50/64/+10/0.06/0.0/256/30       33 SW  VEC1 34 SW  RMY 32
5/5   50/46/48/-7/0.26/0.0/000/00        35 ENE VEC1 35 ENE RMY 36
5/6   61/48/55/0/0.57/0.0/000/00         26 S   VEC1 27 ENE RMY 27
5/7   72/54/63/+8/0.01/0.0/310/36        33 SSW VEC1 33 SW  RMY 35
5/8   74/51/63/+8/0.04/0.0/474/55        18 ESE VEC1 18 ESE RMY 18
5/9   51/46/49/-7/1.15/0.0/000/00        33 E   VEC1 34 ENE RMY 35
5/10  62/45/54/-2/0.29/0.0/121/14        36 NW  VEC1 37 NW  RMY 41
5/11  70/49/60/+4/0.00/0.0/851/98        33 NW  VEC1 32 NW  RMY 34
5/12  73/46/60/+3/0.00/0.0/853/98        36 SW  VEC1 34 SW  RMY 36
5/13  70/51/61/+4/0.00/0.0/759/87        26 ESE VEC1 27 ESE RMY 26
5/14  73/48/61/+4/0.00/0.0/586/67        18 SSE VEC1 19 SSE RMY 17
5/15  72/58/65/+8/0.62/0.0/079/09        20 SSE VEC1 20 SSE RMY 19 TSTM
5/16  78/61/70/+12/0.00/0.0/404/46       23 SW  VEC1 23 SSW RMY 23
5/17  76/58/67/+9/T/0.0/…/..           30 S   VEC1 29 S   RMY 30
5/18  68/54/61/+3/T/0.0/…/..           39 W   VEC1 39 W   RMY 38
5/19  63/46/55/-3/0.00/0.0/…/..        41 NW  VEC1 42 NW  RMY 44

5/20 The low since midnight is 46F, the daily normal low is 49F.

————————————————————–

MAY DAILY RECORDS TO DATE

5/16 RECORD HIGH MINIMUM TEMPERATURE OF 61F;
PREVIOUS RECORD WAS 60F SET IN 2014

————————————————————–

DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated)

RECORDS FOR MAY 20
HIGH 91F IN 1975,1996
LOW 37F IN 1948, 2002
PRECIP 1.97 INCHES IN 2023
PEAK GUST 57 MPH S IN 1963, WNW IN 1982

RECORDS FOR MAY 21
HIGH 92F IN 1921
LOW 35F IN 1907
PRECIP 1.61 INS IN 1954
PEAK GUST 74 MPH WSW IN 2006

TODAY’S REPORT PREPARED BY: Joshua Polen

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Blue Hill Observatory & Science Center · Legal

Data Use & Privacy Policy

Please read the full Policy before accessing Observatory data · Effective January 1, 2025

Notice: By accessing, downloading, or using any Blue Hill Observatory data or services, you unconditionally accept and agree to be bound by this Policy in its entirety. If you do not agree, you may not access or use Observatory data.
Effective January 1, 2025 · Milton, Massachusetts · bluehill.org
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