Hampton Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hampton Beach clear sky chart from 2005-11-06 to 2024-02-25.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	17% 6% 3 5% 5% 3 4 4 5% 7% 41%	78298
	Night	18% 7% 3 5% 5% 3 4 4 5% 6% 40%	80992
Transparency	Day	29% 37% 9% 15% 9% 2	78003
	Night	31% 35% 8% 15% 9% 1	80821
Seeing	Day	19% 9% 28% 30% 12% 2	14043
	Night	20% 10% 31% 28% 10% 1	23060

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 7% 3 5% 4 2 3 4 5% 6% 44%	2517
	11th to 20th	Day	17% 7% 3 6% 4 2 4 4 4 6% 42%	2520
	21st to end	Day	20% 10% 3 5% 4 3 5% 4 4 5% 36%	2772
February	1st to 10th	Day	19% 7% 3 5% 5% 3 5% 5% 6% 7% 36%	1743
	11th to 20th	Day	14% 6% 3 5% 6% 3 4 5% 6% 6% 41%	1848
	21st to end	Day	16% 11% 3 5% 5% 3 4 5% 4 5% 38%	1520
March	1st to 10th	Day	18% 8% 3 5% 4 3 4 5% 5% 9% 37%	1797
	11th to 20th	Day	16% 7% 3 5% 5% 3 4 4 4 7% 40%	1916
	21st to end	Day	19% 8% 3 6% 5% 3 3 3 4 5% 41%	2265
April	1st to 10th	Day	19% 7% 3 5% 6% 3 4 3 4 7% 39%	2160
	11th to 20th	Day	17% 6% 2 4 5% 3 5% 6% 6% 7% 39%	2177
	21st to end	Day	22% 5% 3 5% 5% 4 4 4 4 6% 37%	2340
May	1st to 10th	Day	23% 7% 3 6% 5% 3 4 4 5% 7% 34%	2340
	11th to 20th	Day	18% 6% 3 6% 4 3 3 5% 5% 8% 39%	2325
	21st to end	Day	16% 5% 2 5% 4 2 5% 5% 5% 8% 43%	2725
June	1st to 10th	Day	20% 7% 3 6% 5% 3 5% 4 6% 8% 34%	2520
	11th to 20th	Day	16% 6% 2 5% 5% 3 5% 5% 5% 9% 40%	2520
	21st to end	Day	17% 6% 3 6% 5% 3 5% 5% 6% 8% 35%	2520
July	1st to 10th	Day	15% 4 3 5% 4 3 4 5% 7% 10% 41%	2520
	11th to 20th	Day	11% 7% 2 6% 4 3 5% 5% 7% 10% 40%	2520
	21st to end	Day	12% 4 2 5% 6% 3 5% 6% 8% 8% 42%	2744
August	1st to 10th	Day	9% 5% 2 6% 6% 4 6% 5% 6% 8% 42%	2343
	11th to 20th	Day	12% 6% 2 5% 5% 4 6% 5% 6% 9% 41%	2304
	21st to end	Day	13% 3 2 3 4 2 4 6% 6% 9% 47%	2399
September	1st to 10th	Day	13% 5% 1 4 4 3 4 5% 6% 7% 47%	2138
	11th to 20th	Day	15% 4 2 4 3 2 3 3 3 5% 54%	1980
	21st to end	Day	16% 6% 2 4 4 3 4 3 4 7% 47%	1980
October	1st to 10th	Day	22% 6% 2 5% 3 3 4 3 5% 5% 41%	1980
	11th to 20th	Day	15% 5% 2 4 5% 3 4 4 5% 7% 46%	1752
	21st to end	Day	23% 5% 2 5% 4 3 4 4 5% 6% 40%	1782
November	1st to 10th	Day	17% 6% 2 5% 3 2 3 3 4 5% 49%	1671
	11th to 20th	Day	19% 6% 2 4 3 2 3 3 4 7% 46%	1710
	21st to end	Day	20% 6% 2 5% 3 2 3 4 4 6% 43%	1710
December	1st to 10th	Day	19% 7% 3 5% 5% 2 4 4 5% 6% 39%	1562
	11th to 20th	Day	23% 5% 3 5% 3 2 3 3 4 6% 44%	1906
	21st to end	Day	24% 10% 3 5% 5% 4 4 4 4 6% 34%	2772
January	1st to 10th	Night	19% 7% 2 4 4 2 3 4 4 6% 46%	4429
	11th to 20th	Night	15% 8% 3 7% 6% 3 4 4 5% 6% 40%	4440
	21st to end	Night	22% 11% 3 6% 5% 3 5% 4 5% 5% 31%	4884
February	1st to 10th	Night	16% 9% 2 5% 5% 3 4 5% 5% 6% 38%	2432
	11th to 20th	Night	14% 8% 4 5% 5% 3 4 4 5% 5% 42%	2218
	21st to end	Night	18% 7% 3 4 4 3 4 5% 5% 7% 41%	1831
March	1st to 10th	Night	16% 8% 3 5% 5% 3 5% 3 4 5% 42%	2150
	11th to 20th	Night	18% 8% 3 5% 6% 3 4 5% 5% 6% 37%	2043
	21st to end	Night	19% 8% 2 6% 4 2 4 3 4 5% 43%	2088
April	1st to 10th	Night	19% 9% 3 5% 5% 3 4 4 4 6% 38%	1800
	11th to 20th	Night	19% 6% 2 6% 4 2 4 4 5% 6% 41%	1731
	21st to end	Night	21% 7% 3 7% 5% 3 5% 4 5% 4 37%	1620
May	1st to 10th	Night	23% 8% 3 6% 5% 3 4 4 5% 6% 33%	1620
	11th to 20th	Night	19% 6% 2 6% 4 3 6% 6% 5% 7% 35%	1583
	21st to end	Night	19% 8% 3 5% 4 3 3 4 5% 7% 39%	1550
June	1st to 10th	Night	21% 7% 3 5% 6% 3 4 4 4 6% 35%	1440
	11th to 20th	Night	20% 6% 2 5% 4 2 5% 4 6% 9% 37%	1440
	21st to end	Night	17% 6% 3 5% 5% 3 5% 5% 5% 8% 37%	1440
July	1st to 10th	Night	17% 5% 3 5% 5% 4 5% 5% 5% 9% 38%	1440
	11th to 20th	Night	13% 5% 3 5% 6% 3 5% 6% 7% 10% 38%	1440
	21st to end	Night	14% 4 2 5% 4 3 5% 5% 6% 8% 44%	1574
August	1st to 10th	Night	10% 5% 2 4 5% 3 5% 6% 6% 8% 46%	1576
	11th to 20th	Night	14% 6% 2 6% 6% 4 5% 5% 7% 9% 36%	1596
	21st to end	Night	14% 5% 2 4 4 3 4 5% 6% 8% 45%	1954
September	1st to 10th	Night	13% 5% 2 5% 5% 2 4 4 5% 7% 48%	1822
	11th to 20th	Night	15% 5% 2 4 4 2 3 3 4 6% 52%	1980
	21st to end	Night	14% 5% 2 5% 5% 3 3 4 5% 7% 46%	1980
October	1st to 10th	Night	22% 6% 3 5% 5% 2 3 4 6% 6% 40%	1980
	11th to 20th	Night	16% 5% 2 5% 4 3 4 4 5% 6% 44%	2202
	21st to end	Night	24% 7% 2 5% 4 3 3 4 4 5% 38%	2574
November	1st to 10th	Night	15% 6% 2 4 4 3 5% 4 4 6% 47%	2407
	11th to 20th	Night	17% 6% 2 5% 4 3 4 3 4 6% 46%	2470
	21st to end	Night	17% 6% 3 4 4 3 4 4 5% 6% 45%	2470
December	1st to 10th	Night	20% 9% 3 5% 5% 3 4 4 5% 5% 38%	2616
	11th to 20th	Night	20% 6% 2 5% 5% 3 3 4 5% 6% 41%	3288
	21st to end	Night	23% 9% 3 6% 5% 3 4 4 3 5% 36%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	30% 27% 9% 26% 7%	2518
	11th to 20th	Day	34% 27% 9% 20% 9% 1	2520
	21st to end	Day	40% 25% 8% 21% 5% 1	2772
February	1st to 10th	Day	30% 36% 9% 15% 8% 2	1743
	11th to 20th	Day	26% 37% 10% 16% 9% 2	1857
	21st to end	Day	34% 36% 8% 13% 7% 2	1520
March	1st to 10th	Day	30% 38% 9% 13% 8% 2	1800
	11th to 20th	Day	30% 37% 8% 14% 9% 2	1916
	21st to end	Day	27% 37% 5% 14% 12% 4	2265
April	1st to 10th	Day	29% 38% 7% 11% 12% 2	2160
	11th to 20th	Day	29% 37% 9% 14% 9% 2	2177
	21st to end	Day	29% 39% 6% 12% 11% 3	2340
May	1st to 10th	Day	33% 36% 6% 13% 10% 2	2340
	11th to 20th	Day	29% 38% 7% 12% 11% 3	2329
	21st to end	Day	25% 39% 9% 15% 10% 2	2725
June	1st to 10th	Day	34% 38% 8% 13% 5%	2520
	11th to 20th	Day	28% 39% 10% 13% 8% 2	2520
	21st to end	Day	31% 39% 10% 13% 6% 1	2520
July	1st to 10th	Day	27% 40% 11% 15% 7% 1	2450
	11th to 20th	Day	25% 39% 11% 17% 7%	2445
	21st to end	Day	23% 41% 10% 16% 8% 2	2591
August	1st to 10th	Day	26% 41% 10% 16% 7%	2329
	11th to 20th	Day	26% 38% 10% 17% 9% 1	2304
	21st to end	Day	21% 40% 10% 16% 12% 2	2399
September	1st to 10th	Day	23% 39% 9% 16% 13%	2138
	11th to 20th	Day	21% 37% 7% 20% 14% 2	1980
	21st to end	Day	27% 37% 7% 15% 13% 1	1980
October	1st to 10th	Day	28% 37% 7% 15% 12% 1	1980
	11th to 20th	Day	26% 38% 8% 19% 7% 1	1752
	21st to end	Day	27% 38% 8% 15% 10% 2	1782
November	1st to 10th	Day	23% 41% 8% 17% 11% 1	1671
	11th to 20th	Day	22% 41% 8% 16% 12% 1	1710
	21st to end	Day	27% 41% 11% 15% 7%	1710
December	1st to 10th	Day	29% 41% 10% 11% 8% 1	1562
	11th to 20th	Day	31% 32% 9% 13% 10% 4	1906
	21st to end	Day	41% 27% 9% 16% 6% 1	2772
January	1st to 10th	Night	31% 26% 11% 24% 7% 2	4429
	11th to 20th	Night	35% 27% 9% 17% 10% 3	4440
	21st to end	Night	45% 25% 8% 15% 7% 1	4884
February	1st to 10th	Night	30% 37% 10% 13% 9% 1	2432
	11th to 20th	Night	30% 36% 8% 14% 10% 2	2220
	21st to end	Night	29% 36% 9% 16% 7% 2	1831
March	1st to 10th	Night	29% 37% 6% 15% 10% 3	2160
	11th to 20th	Night	33% 37% 9% 12% 8% 1	2044
	21st to end	Night	29% 36% 7% 11% 14% 3	2088
April	1st to 10th	Night	30% 38% 8% 13% 10% 2	1800
	11th to 20th	Night	30% 36% 6% 13% 13% 1	1731
	21st to end	Night	33% 37% 6% 11% 10% 2	1620
May	1st to 10th	Night	34% 36% 5% 13% 9% 2	1620
	11th to 20th	Night	32% 39% 8% 10% 8% 3	1584
	21st to end	Night	27% 39% 10% 13% 9% 2	1551
June	1st to 10th	Night	35% 36% 8% 13% 7% 1	1440
	11th to 20th	Night	31% 39% 9% 10% 9% 2	1440
	21st to end	Night	32% 39% 10% 11% 7%	1440
July	1st to 10th	Night	33% 40% 9% 13% 5% 1	1400
	11th to 20th	Night	26% 40% 11% 16% 6%	1392
	21st to end	Night	25% 40% 10% 17% 6% 1	1486
August	1st to 10th	Night	26% 40% 9% 17% 7%	1566
	11th to 20th	Night	29% 38% 11% 13% 9%	1596
	21st to end	Night	26% 38% 8% 17% 10% 1	1954
September	1st to 10th	Night	24% 38% 8% 17% 13% 1	1822
	11th to 20th	Night	22% 37% 7% 18% 15% 1	1980
	21st to end	Night	25% 38% 8% 15% 13% 2	1980
October	1st to 10th	Night	30% 37% 8% 14% 9% 1	1980
	11th to 20th	Night	29% 39% 8% 17% 7% 1	2202
	21st to end	Night	30% 38% 8% 14% 9% 1	2574
November	1st to 10th	Night	23% 41% 9% 15% 11% 2	2407
	11th to 20th	Night	26% 40% 7% 16% 10% 1	2470
	21st to end	Night	27% 40% 8% 15% 8% 1	2470
December	1st to 10th	Night	31% 41% 8% 14% 6% 1	2616
	11th to 20th	Night	29% 34% 10% 13% 13%	3288
	21st to end	Night	41% 26% 7% 19% 7%	4884

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	24% 17% 26% 27% 7%	180
	11th to 20th	Day	20% 21% 33% 19% 7%	180
	21st to end	Day	19% 15% 32% 28% 6%	198
February	1st to 10th	Day	24% 16% 36% 21% 2	365
	11th to 20th	Day	20% 19% 40% 18% 3	456
	21st to end	Day	20% 16% 33% 27% 4	362
March	1st to 10th	Day	20% 15% 35% 26% 5%	420
	11th to 20th	Day	19% 16% 37% 24% 3 1	420
	21st to end	Day	23% 15% 34% 20% 6% 2	462
April	1st to 10th	Day	23% 13% 35% 21% 7% 2	420
	11th to 20th	Day	19% 12% 41% 20% 8% 1	412
	21st to end	Day	25% 7% 33% 28% 7% 1	420
May	1st to 10th	Day	27% 8% 34% 23% 7% 1	423
	11th to 20th	Day	16% 9% 32% 32% 9% 2	447
	21st to end	Day	20% 3 26% 35% 14% 3	485
June	1st to 10th	Day	20% 3 25% 34% 16% 3	450
	11th to 20th	Day	14% 5% 30% 36% 14% 2	450
	21st to end	Day	18% 2 26% 38% 14% 3	450
July	1st to 10th	Day	18% 2 12% 41% 23% 4	445
	11th to 20th	Day	14% 3 16% 39% 23% 4	444
	21st to end	Day	10% 2 16% 51% 19% 2	488
August	1st to 10th	Day	11% 2 19% 37% 28% 3	446
	11th to 20th	Day	14% 4 17% 36% 24% 6%	439
	21st to end	Day	14% 3 16% 43% 19% 6%	495
September	1st to 10th	Day	16% 3 23% 30% 21% 7%	450
	11th to 20th	Day	19% 6% 23% 28% 18% 7%	450
	21st to end	Day	16% 4 28% 30% 16% 6%	450
October	1st to 10th	Day	26% 6% 22% 24% 17% 4	450
	11th to 20th	Day	15% 11% 26% 31% 15% 2	385
	21st to end	Day	26% 8% 30% 25% 11% 1	396
November	1st to 10th	Day	15% 11% 32% 28% 12% 3	365
	11th to 20th	Day	23% 15% 31% 25% 6% 1	370
	21st to end	Day	23% 14% 28% 24% 10% 1	370
December	1st to 10th	Day	20% 9% 40% 23% 8%	222
	11th to 20th	Day	21% 17% 39% 21% 3	180
	21st to end	Day	23% 17% 32% 21% 6% 2	198
January	1st to 10th	Night	21% 18% 39% 19% 3	760
	11th to 20th	Night	24% 17% 39% 17% 3	760
	21st to end	Night	19% 19% 38% 20% 4	836
February	1st to 10th	Night	22% 16% 38% 23% 2	760
	11th to 20th	Night	19% 17% 45% 16% 3	743
	21st to end	Night	22% 14% 37% 23% 4	611
March	1st to 10th	Night	21% 16% 37% 22% 3	720
	11th to 20th	Night	20% 14% 38% 22% 5%	720
	21st to end	Night	23% 11% 34% 24% 7%	792
April	1st to 10th	Night	23% 13% 33% 26% 5%	720
	11th to 20th	Night	23% 7% 35% 25% 9% 1	667
	21st to end	Night	23% 8% 31% 30% 7% 1	540
May	1st to 10th	Night	27% 5% 31% 29% 8% 1	540
	11th to 20th	Night	21% 5% 30% 33% 9% 1	522
	21st to end	Night	22% 5% 22% 36% 14% 2	389
June	1st to 10th	Night	23% 5% 21% 36% 13% 3	360
	11th to 20th	Night	21% 4 20% 40% 13% 1	360
	21st to end	Night	20% 3 17% 43% 16% 1	360
July	1st to 10th	Night	18% 2 15% 44% 19% 3	350
	11th to 20th	Night	13% 3 12% 47% 23% 1	348
	21st to end	Night	14% 3 13% 48% 20% 1	394
August	1st to 10th	Night	12% 2 14% 44% 26% 1	502
	11th to 20th	Night	15% 3 15% 42% 23% 2	532
	21st to end	Night	15% 3 16% 37% 25% 3	766
September	1st to 10th	Night	15% 2 23% 34% 23% 3	720
	11th to 20th	Night	16% 6% 22% 33% 18% 5%	720
	21st to end	Night	17% 3 24% 32% 19% 4	720
October	1st to 10th	Night	24% 6% 24% 27% 16% 3	720
	11th to 20th	Night	18% 8% 29% 30% 13% 2	720
	21st to end	Night	26% 8% 31% 26% 9%	792
November	1st to 10th	Night	16% 9% 35% 29% 10% 1	740
	11th to 20th	Night	20% 13% 36% 23% 7% 1	760
	21st to end	Night	20% 18% 34% 23% 5% 1	760
December	1st to 10th	Night	23% 13% 40% 19% 4 1	760
	11th to 20th	Night	22% 17% 35% 22% 3	760
	21st to end	Night	24% 16% 38% 20% 2	836

Page generated at 2024-02-22 06:05:43. Version ac07

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