Thursday, May 21, 2026

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

THURSDAY, MAY 21, 2026
ALL TIMES ARE IN EASTERN STANDARD TIME (EST)
SUNRISE: 0417E
SUNSET: 1905E

LOTS OF CLOUDS TODAY WITH MUCH COOLER TEMPERATURES….

High pressure north of the Great Lakes is sliding eastward over
southern Canada, meanwhile a cold front is stalled just south of
southern New England.

Since the cold front is slow to move out, clouds have been
lingering over the area today. Some very light rain also occurred
for a few hours this morning, but it only amounted to 0.01″.

Temperatures are much cooler today than it was the last couple of
days. Readings have reached the mid to upper 60s today, which is
very refreshing after the upper 80s and 90s we just experienced.
Dew point values are much more comfortable today as well with
readings in the mid to upper 40s!

Winds were steady overnight out of the north to north-northwest,
but diminished quite a bit during the morning hours, becoming
light and variable by early this afternoon. The average speed for
the day so far is around 8mph. The peak gust so far for the day
is 22mph, which occurred around 5:30am this morning.

Visibility has been great most of the day with a view of 70-80
miles. It was lower in the southern quadrants early this morning
to the light rain.

The maximum temperature so far today is 68F degrees, which is
equal to the normal high of 68F. The minimum temperature since
midnight is 57F degrees, which is 7 degrees above the normal low
of 50F.

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Today’s Observations:

7 A.M.
Weather: Overcast altocumulus/nimbostratus, very light rain
Temperature: 58F; Dew Point: 48F; Relative Humidity: 70%
Wind: NNW @ 7 kts
Sea-level pressure: 1022.2 mb; 30.19 in. Hg: rising, then more slowly
Visibility: 80 miles, 10 miles SE, 20 miles SW-W
6-hr Max temp: 66F
6-hr Min temp: 57F
24-hr Precip: Trace
BHO SA 1155 E85 OVC 80R- 222/58/48/3407/019/ PCPN VRY LGT
VSBY 10 SE 20 SW-W/ 8/07/ 51028 6000/ 70000 10066 20057

10 A.M.
Weather: Broken altocumulus/altostratus, overcast cirrostratus
Temperature: 64F; Dew Point: 46F; Relative Humidity: 53%
Wind: NE @ 5kts, wind light
Sea-level pressure: 1023.2 mb; 30.22 in. Hg: rising unsteadily
Visibility: 70 miles
3-hr Precip: 0.01 inches
BHO SA 1455 E150 BKN 200 OVC 70 232/64/46/0505/022/ FEW CU DSNT SSW
SUN DMLY VSBL WND LGT/ 8/277 52010 6001/

1 P.M.
Weather: Broken altostratus, overcast cirrostratus, clearing line
distant WNW-NNE, few stratocumulus SE-S
Temperature: 66F; Dew Point: 47F; Relative Humidity: 50%
Wind: NNE @ 2 kts, wind light and variable
Sea-level pressure: 1023.2 mb; 30.22 in. Hg: falling, then rising
Visibility: 70 miles
6-hr Max temp: 67F
6-hr Min temp: 57F
6-hr Precip: 0.01 inches
BHO SA 1755 E150 BKN 200 OVC 70 232/66/47/0302/022/
CLRG LINE DSNT WNW-NNE FEW SC SE-S WND L/V/ 8/527 55000 6001/
10067 20057

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SUMMARY FOR WEDNESDAY, MAY 20, 2026

TEMPERATURE (DEGREES F)
MAX…….89 NORMAL…..68
MIN…….65 NORMAL…..49
MEAN……77 NORMAL…..59

DEPARTURE FROM 30-YEAR (1991-2020) NORMAL……………+18
TOTAL DEPARTURE FOR THE MONTH………………………+64 [+3.0 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026)
TOTAL HEATING UNITS FOR YESTERDAY……………..0 DEPARTURE……..-8
TOTAL HEATING UNITS FOR THE MONTH (MAY)………155 DEPARTURE…….-35
TOTAL HEATING UNITS FOR THE SEASON………….5991 DEPARTURE…….-86
TOTAL HEATING UNITS LAST SEASON TO DATE……..5500 DEPARTURE……+476

COOLING DEGREE DAYS (SEASON: JAN 2026 THRU DEC 2026)
TOTAL COOLING UNITS FOR YESTERDAY…………….12 DEPARTURE…….+11
TOTAL COOLING UNITS FOR THE MONTH (MAY)……….41 DEPARTURE…….+30
TOTAL COOLING UNITS FOR THE SEASON……………47 DEPARTURE…….+33
TOTAL COOLING UNITS LAST SEASON TO DATE……….14 DEPARTURE…….+33

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 *=Last of multiple occurrences

F420C (Official)………..39 WNW @ 05:30 P.M.
VECTOR #1 (1-Sec)……….38 WNW @ 05:29 P.M.
VECTOR #2 (1-Sec)……….38 WNW @ 03:00 P.M.
DAVIS #1……………….38 WNW @ 05:29 P.M.
DAVIS #2 ………………35 WNW @ 05:30 P.M.
RMY #1 (Instantaneous)…..41 WNW @ 05:29 P.M.
RMY #2 (Instantaneous)…..38 WNW @ 05:23 P.M.
MERLIN…………………38 NW
RICHARDS (C5C) (Inst)……39 WNW @ 05:29 P.M.

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL………………27 WNW @ 05:31 P.M.
MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..26 WNW @ 05:29 P.M.
MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..29 WNW @ 05:25 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………27 WNW @ 05:29 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………28 WNW @ 05:31 P.M.
MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..25 WNW @ 05:29 P.M.
MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..28 WNW @ 05:25 P.M.
MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………26 WNW @ 05:29 P.M.

AVERAGE WIND SPEED AND DIRECTION:
CONTACTING/OFFICIAL……..14.1 WNW [339 total miles] VECTOR #1………………14.1
VECTOR #2………………14.9
DAVIS #1……………….14.4 W
DAVIS #2……………….14.3 W
RMY #1…………………13.8 W
RMY #2…………………14.6 W
RICHARDS (C5C)………….13.7

PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M…….TRACE DEPARTURE…..-0.12
TOTAL PRECIPITATION FOR THE MONTH (MAY)……..1.29 DEPARTURE…..-1.09
TOTAL PRECIPITATION FOR THE YEAR (2026)…….14.96 DEPARTURE…..-6.20

SNOWFALL (INCHES) THROUGH THIS MORNING (EST):
TOTAL SNOWFALL 24 HRS ENDING 7 A.M…………..0.0 DEPARTURE……0.0
TOTAL SNOWFALL FOR THE MONTH (MAY)…………..0.0 DEPARTURE……0.0
TOTAL SNOWFALL FOR THE SEASON (2025-2026)……81.6 DEPARTURE….+11.9

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PRELIMINARY CLIMATE SUMMARY FOR MAY 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

5/1 63/43/53/0/0.00/769/91 26 WNW VEC1 27 NNW RMY 27
5/2 58/45/52/-2/0.04/127/15 29 SSW VEC1 29 SSW RMY 28
5/3 53/41/47/-7/T/119/14 37 NW VEC1 36 NW RMY 39
5/4 71/41/56/+2/0.00/775/91 46 SW VEC1 46 SW RMY 48
5/5 78/49/64/+9/0.00/718/84 43 SSW VEC1 43 SSW RMY 45
5/6 68/54/61/+6/0.08/146/17 43 SSW VEC1 42 SSW RMY 44
5/7 65/46/56/+1/0.22/697/81 28 WNW VEC1 27 WNW RMY 28
5/8 62/40/51/-4/0.00/741/86 33 W VEC1 33 W RMY 33
5/9 58/43/51/-5/0.35/000/00 30 SSW VEC1 31 SSW RMY 30
5/10 72/49/61/+5/T/346/40 28 SSW VEC1 28 SSW RMY 27
5/11 62/45/54/-2/T/191/22 26 NNW VEC1 26 NNW RMY 26
5/12 63/42/53/-4/T/835/96 29 WNW VEC1 29 WNW RMY 29
5/13 65/46/56/-1/T/122/14 41 S VEC1 40 S RMY 44
5/14 61/48/55/-2/0.26/000/00 37 SSE VEC1 38 SE RMY 36
5/15 56/47/52/-5/0.04/026/03 18 NE VEC1 19 NE RMY 20
5/16 78/47/63/+5/0.00/853/97 33 SW VEC1 34 SSW RMY 35
5/17 86/56/71/+13/0.05/827/94 39 W VEC1 38 W RMY 40
5/18 84/62/73/+15/0.00/829/94 33 SSW VEC1 32 SSW RMY 33
5/19 95/65/80/+22/0.25/716/81 47 NW VEC1 47 NW RMY 50 TSTM
5/20 89/65/77/+18/0.00/789/89 39 WNW VEC1 39 WNW RMY 41