Wednesday, May 21, 2025

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

WEDNESDAY, MAY 21, 2025
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0417E
SUNSET:  1905E

OVERCAST AND CHILLY TODAY AS WE’RE STUCK BETWEEN SYSTEMS….

Skies have been overcast all day with a raw easterly wind keeping
the air mass on the chilly side. Periods of light drizzle have been
observed since last evening, but it’s been very light for the most
part only amounting to 0.01″ total.

Temperatures are well below normal for the day, at least in terms
maximum temperatures. Values have been stuck in the 40s all day only
reaching the upper 40s to this point. This is a solid 20 degrees
below expected values for the date.

The easterly flow has been raw today averaging at around 9mph for
the day so far. Gusts have frequently exceeded 20mph adding to the
discomfort of the air. The peak gust occurred this morning around
9:20am, with a speed of 26mph.

Visibility has been variable, reaching as high as 70 miles during
the mid to late morning hours. Otherwise it’s been around 30 miles
for the most part, dropping lower at times due to areas of drizzle.

The maximum temperature for today is 48F degrees, which is 20 degrees
below the normal high of 68F. The minimum temperature since midnight
is 43F degrees, which is 7 degrees below the normal low of 50F.

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Today’s Observations:

7 A.M.
Weather: Broken stratocumulus, overcast altostratus, few breaks in
overcast all quadrants
Temperature: 47F; Dew Point: 40F; Relative Humidity: 76%
Wind: ENE @ 12G21 kts
Sea-level pressure: 1019.5 mb; 30.11 in. Hg: rising, then falling
Visibility: 40 miles
6-hr Max temp: 47F
6-hr Min temp: 43F
24-hr Precip:  0.01 inches
24-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1155 E20 BKN 40 OVC 40 195/47/40/0612G21/011/ FEW BINOVC ALQDS/
8/52/ 50005 6001/ 70001 10047 20043

10 A.M.
Weather: Overcast stratocumulus
Temperature: 46F; Dew Point: 38F; Relative Humidity: 67%
Wind: NE @ 12G21 kts
Sea-level pressure: 1019.5 mb; 30.11 in. Hg: falling, then rising
Visibility: 70 miles
3-hr Precip:  0.00 inches
3-hr Snowfall: 0.0 inches
BHO SA 1455 E20 OVC 70 195/46/38/0512G21/011/ 8/5// 55000

1 P.M.
Weather: Overcast stratocumulus, intermittent light drizzle
Temperature: 47F Dew Point: 40F; Relative Humidity: 76%
Wind: E @ 10G19 kts
Sea-level pressure: 1018.9 mb; 30.09 in. Hg: rising, then falling
Visibility: 30 miles, 10 mile W-NW
6-hr Max temp: 48F
6-hr Min temp: 45F
6-hr Precip:  Trace
6-hr Snowfall: 0.0 inches
Snow Depth: 0 inches
BHO SA 1755 E20 OVC 30 189/47/40/0810G19/009/ INTMT L- VSBY 10 W-NW/
8/5// 58006 6000/ 10048 20045

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SUMMARY FOR TUESDAY, MAY 20, 2025

TEMPERATURE (DEGREES F)
MAX…….55   NORMAL…..68
MIN…….45   NORMAL…..49
MEAN……50   NORMAL…..59

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….-9
TOTAL DEPARTURE FOR THE MONTH………………………+72 [+3.4 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2024 THRU JUN 2025)
TOTAL HEATING UNITS FOR YESTERDAY…………….15  DEPARTURE……..+8
TOTAL HEATING UNITS FOR THE MONTH……………117  DEPARTURE…….-73
TOTAL HEATING UNITS FOR THE SEASON………….5515  DEPARTURE……-562
TOTAL HEATING UNITS LAST SEASON TO DATE……..5365  DEPARTURE……+150

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………0
TOTAL COOLING UNITS FOR THE SEASON……………14  DEPARTURE………0
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)………..29 NNW  @   12:26 A.M.
VECTOR #1 (1-Sec)……….29 NNW  @   12:58 A.M.
VECTOR #2 (1-Sec)……….29 NW   @   03:46 A.M.
DAVIS #1……………….28 NNW  @   12:27 A.M.
DAVIS #2 ………………25 NNW  @   03:46 A.M.
RMY #1 (Instantaneous)…..30 NNW  @   12:26 A.M.
RMY #2 (Instantaneous)…..30 NW   @   03:46 A.M.
MERLIN………………….M
RICHARDS (C5C) (Inst)…..OTS

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………18 NNW  @   12:36 A.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..19      @   12:27 A.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..18      @   12:54 A.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………19 NW   @   01:00 A.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………18 NNW  @   03:33 A.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..18 NW   @   12:27 A.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..18 NW   @   12:54 A.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE……..OTS

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL………9.5 NNW [227 total miles] VECTOR #1……………….9.3
VECTOR #2………………10.0
DAVIS #1………………..9.8 NNE
DAVIS #2………………..9.9 NNE
RMY #1………………….9.4 NNE
RMY #2………………….9.8 NNE
RICHARDS (C5C)…………..OTS

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.01 DEPARTURE…..-0.11
TOTAL PRECIPITATION FOR THE MONTH…………..3.35 DEPARTURE…..+0.97
TOTAL PRECIPITATION FOR THE YEAR (2025)…….17.47 DEPARTURE…..-3.69

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

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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  55/45/50/-9/T/0.0/…/..           29 NNW VEC1 29 NNW RMY 30

5/21 The low since midnight is 43F, the daily normal low is 50F.

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MAY DAILY RECORDS TO DATE

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

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

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

RECORDS FOR MAY 22
HIGH 93F IN 1911, 2022
LOW 35F IN 1907
PRECIP 3.75 INCHES IN 1920
PEAK GUST 49e MPH SSW IN 1947

TODAY’S REPORT PREPARED BY: MFD