Hampton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hampton clear sky chart from 2005-11-06 to 2024-01-12.

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	20% 10% 3 6% 5% 3 4 4 5% 6% 33%	74677
	Night	21% 10% 4 7% 6% 3 4 4 5% 6% 32%	75046
Transparency	Day	52% 6% 11% 19% 10% 1	74380
	Night	54% 6% 11% 18% 10% 1	74878
Seeing	Day	30% 20% 29% 16% 5% 1	15385
	Night	28% 17% 29% 21% 5%	23315

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	15% 15% 5% 11% 6% 2 4 4 4 5% 30%	1327
	11th to 20th	Day	22% 15% 5% 9% 5% 3 3 3 2 4 29%	1404
	21st to end	Day	12% 12% 4 7% 4 3 5% 4 5% 6% 38%	1782
February	1st to 10th	Day	17% 12% 5% 7% 6% 3 4 5% 5% 6% 30%	1620
	11th to 20th	Day	18% 14% 4 8% 6% 3 3 4 4 7% 29%	1573
	21st to end	Day	11% 12% 5% 7% 6% 5% 4 4 5% 6% 34%	1408
March	1st to 10th	Day	16% 17% 6% 8% 5% 3 4 4 4 4 30%	1917
	11th to 20th	Day	16% 13% 4 7% 7% 4 4 3 4 6% 33%	1980
	21st to end	Day	19% 13% 4 7% 7% 2 3 3 4 4 33%	2178
April	1st to 10th	Day	24% 14% 5% 6% 6% 3 5% 4 4 5% 25%	2089
	11th to 20th	Day	21% 12% 4 5% 5% 3 3 4 5% 6% 34%	2312
	21st to end	Day	24% 11% 3 6% 4 3 4 3 5% 6% 30%	2340
May	1st to 10th	Day	25% 11% 4 6% 5% 2 4 5% 4 6% 28%	2340
	11th to 20th	Day	24% 7% 3 5% 5% 3 4 4 4 5% 35%	2451
	21st to end	Day	20% 9% 3 7% 6% 3 4 4 5% 8% 31%	2730
June	1st to 10th	Day	26% 10% 4 5% 5% 3 5% 4 5% 6% 27%	2700
	11th to 20th	Day	22% 9% 3 6% 5% 2 4 4 5% 6% 34%	2700
	21st to end	Day	29% 8% 3 5% 4 3 4 4 5% 7% 28%	2700
July	1st to 10th	Day	20% 7% 2 5% 5% 3 5% 5% 6% 7% 34%	2700
	11th to 20th	Day	18% 8% 2 5% 5% 3 4 4 6% 9% 34%	2700
	21st to end	Day	20% 7% 3 6% 6% 4 5% 5% 6% 7% 31%	2584
August	1st to 10th	Day	18% 7% 3 5% 6% 3 5% 5% 5% 7% 35%	2327
	11th to 20th	Day	19% 7% 2 6% 6% 3 5% 6% 6% 8% 32%	2304
	21st to end	Day	17% 6% 3 5% 5% 3 4 4 5% 8% 41%	2558
September	1st to 10th	Day	14% 6% 3 5% 4 3 5% 5% 5% 8% 42%	2160
	11th to 20th	Day	20% 6% 2 5% 4 2 4 4 3 6% 45%	1987
	21st to end	Day	23% 6% 2 3 2 2 3 4 4 6% 45%	1980
October	1st to 10th	Day	20% 7% 3 5% 5% 2 3 3 5% 6% 40%	1810
	11th to 20th	Day	21% 9% 3 6% 4 3 4 4 4 6% 36%	1800
	21st to end	Day	21% 11% 3 7% 5% 3 4 4 5% 6% 31%	1907
November	1st to 10th	Day	23% 10% 3 6% 5% 2 3 3 4 5% 34%	1581
	11th to 20th	Day	19% 11% 4 6% 5% 3 4 4 4 6% 34%	1520
	21st to end	Day	20% 13% 5% 8% 5% 3 4 4 4 5% 29%	1520
December	1st to 10th	Day	25% 11% 5% 8% 6% 3 3 4 5% 5% 25%	1520
	11th to 20th	Day	22% 14% 5% 9% 7% 3 3 4 4 5% 24%	1737
	21st to end	Day	21% 10% 4 8% 7% 2 4 5% 4 4 32%	2431
January	1st to 10th	Night	17% 12% 5% 8% 6% 3 6% 5% 4 4 29%	2838
	11th to 20th	Night	19% 13% 4 8% 6% 3 5% 4 4 6% 28%	2589
	21st to end	Night	15% 9% 4 7% 6% 4 4 5% 4 7% 34%	2574
February	1st to 10th	Night	18% 11% 3 7% 5% 4 5% 4 5% 6% 31%	2340
	11th to 20th	Night	18% 13% 5% 8% 6% 3 4 4 5% 6% 28%	2273
	21st to end	Night	13% 10% 6% 8% 8% 4 5% 4 4 6% 32%	1844
March	1st to 10th	Night	15% 14% 4 7% 5% 3 5% 3 4 5% 32%	2029
	11th to 20th	Night	18% 11% 4 7% 8% 4 4 4 5% 6% 29%	1979
	21st to end	Night	18% 12% 4 8% 6% 3 4 3 4 5% 32%	2178
April	1st to 10th	Night	23% 14% 3 7% 6% 3 5% 4 4 4 27%	1869
	11th to 20th	Night	23% 10% 3 5% 5% 4 4 4 5% 6% 33%	1598
	21st to end	Night	24% 11% 3 6% 6% 2 5% 4 4 7% 28%	1620
May	1st to 10th	Night	22% 10% 4 6% 6% 3 4 5% 5% 6% 28%	1620
	11th to 20th	Night	26% 9% 4 5% 5% 2 4 5% 5% 5% 31%	1440
	21st to end	Night	20% 11% 3 6% 5% 3 5% 5% 5% 7% 30%	1550
June	1st to 10th	Night	27% 7% 3 7% 7% 4 4 4 5% 6% 25%	1269
	11th to 20th	Night	22% 9% 4 5% 6% 2 4 4 5% 6% 33%	1260
	21st to end	Night	30% 8% 3 5% 5% 3 4 4 4 6% 29%	1260
July	1st to 10th	Night	19% 9% 4 7% 5% 3 4 5% 6% 8% 29%	1260
	11th to 20th	Night	21% 8% 3 6% 5% 4 4 4 6% 7% 31%	1260
	21st to end	Night	20% 10% 4 6% 6% 3 6% 5% 6% 7% 27%	1711
August	1st to 10th	Night	17% 6% 3 5% 5% 4 5% 6% 5% 7% 36%	1612
	11th to 20th	Night	21% 8% 3 6% 5% 4 5% 4 6% 8% 30%	1596
	21st to end	Night	16% 7% 3 4 5% 3 4 5% 6% 8% 40%	1797
September	1st to 10th	Night	18% 7% 2 5% 5% 2 4 5% 5% 7% 40%	1800
	11th to 20th	Night	21% 7% 2 5% 4 2 3 3 4 7% 42%	1970
	21st to end	Night	22% 5% 2 4 4 2 4 5% 4 6% 41%	1980
October	1st to 10th	Night	21% 7% 3 5% 4 3 3 4 5% 8% 39%	2150
	11th to 20th	Night	17% 11% 3 6% 5% 4 4 4 5% 6% 37%	2160
	21st to end	Night	23% 10% 3 6% 5% 3 4 3 4 5% 32%	2448
November	1st to 10th	Night	22% 9% 3 6% 4 3 4 4 4 6% 34%	2497
	11th to 20th	Night	20% 9% 4 7% 5% 3 5% 4 5% 6% 32%	2660
	21st to end	Night	21% 11% 4 7% 6% 3 4 3 4 6% 31%	2660
December	1st to 10th	Night	26% 11% 4 8% 6% 3 4 4 4 5% 25%	2660
	11th to 20th	Night	26% 12% 4 7% 6% 3 4 4 4 4 26%	3459
	21st to end	Night	22% 13% 5% 8% 6% 2 4 3 3 4 30%	5236

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	58% 5% 13% 14% 10% 1	1328
	11th to 20th	Day	61% 5% 8% 17% 8% 1	1404
	21st to end	Day	47% 5% 10% 20% 16% 1	1782
February	1st to 10th	Day	54% 5% 11% 17% 10% 2	1620
	11th to 20th	Day	57% 4 12% 16% 9% 1	1581
	21st to end	Day	50% 5% 11% 21% 10% 3	1408
March	1st to 10th	Day	59% 4 8% 18% 10% 2	1921
	11th to 20th	Day	54% 4 11% 16% 14% 2	1980
	21st to end	Day	56% 3 8% 16% 13% 4	2178
April	1st to 10th	Day	62% 5% 8% 12% 11% 2	2089
	11th to 20th	Day	51% 4 10% 20% 13% 1	2312
	21st to end	Day	56% 5% 10% 15% 11% 3	2340
May	1st to 10th	Day	59% 5% 9% 16% 10% 1	2340
	11th to 20th	Day	51% 6% 9% 21% 11% 1	2455
	21st to end	Day	53% 7% 11% 20% 8% 1	2730
June	1st to 10th	Day	58% 6% 10% 17% 8%	2700
	11th to 20th	Day	52% 5% 12% 19% 10% 1	2700
	21st to end	Day	57% 7% 11% 15% 9% 1	2700
July	1st to 10th	Day	48% 9% 14% 19% 10% 1	2625
	11th to 20th	Day	47% 8% 16% 21% 8% 1	2619
	21st to end	Day	51% 9% 14% 19% 7%	2439
August	1st to 10th	Day	47% 9% 15% 20% 8%	2314
	11th to 20th	Day	49% 8% 15% 23% 6%	2304
	21st to end	Day	42% 8% 14% 25% 12%	2558
September	1st to 10th	Day	41% 7% 14% 24% 14% 1	2160
	11th to 20th	Day	43% 4 11% 24% 14% 3	1987
	21st to end	Day	41% 5% 10% 25% 17% 1	1980
October	1st to 10th	Day	46% 5% 10% 26% 13%	1810
	11th to 20th	Day	50% 5% 12% 25% 8%	1800
	21st to end	Day	54% 6% 11% 17% 12%	1907
November	1st to 10th	Day	55% 5% 10% 20% 10% 1	1581
	11th to 20th	Day	51% 5% 13% 18% 12% 1	1520
	21st to end	Day	58% 5% 12% 18% 7%	1520
December	1st to 10th	Day	61% 5% 10% 17% 6% 1	1520
	11th to 20th	Day	62% 5% 10% 13% 9% 1	1737
	21st to end	Day	56% 4 16% 15% 8% 2	2431
January	1st to 10th	Night	58% 6% 10% 17% 8% 1	2838
	11th to 20th	Night	59% 6% 9% 16% 8% 1	2589
	21st to end	Night	49% 6% 11% 20% 12% 2	2574
February	1st to 10th	Night	53% 6% 12% 16% 12% 1	2340
	11th to 20th	Night	57% 5% 10% 15% 10% 2	2276
	21st to end	Night	53% 5% 11% 17% 12% 2	1844
March	1st to 10th	Night	54% 5% 8% 18% 13% 2	2038
	11th to 20th	Night	56% 5% 9% 14% 13% 2	1980
	21st to end	Night	55% 4 9% 17% 13% 3	2178
April	1st to 10th	Night	60% 5% 8% 13% 10% 4	1869
	11th to 20th	Night	52% 4 11% 19% 13% 1	1598
	21st to end	Night	56% 6% 10% 15% 12% 1	1620
May	1st to 10th	Night	56% 7% 9% 16% 10% 2	1620
	11th to 20th	Night	53% 8% 10% 19% 9% 1	1441
	21st to end	Night	54% 8% 10% 17% 10% 1	1551
June	1st to 10th	Night	60% 6% 10% 17% 6% 1	1269
	11th to 20th	Night	52% 7% 11% 21% 8% 2	1260
	21st to end	Night	59% 7% 8% 16% 9% 1	1260
July	1st to 10th	Night	53% 9% 13% 16% 8%	1225
	11th to 20th	Night	52% 10% 10% 20% 9%	1218
	21st to end	Night	55% 9% 13% 15% 7% 1	1616
August	1st to 10th	Night	46% 10% 14% 22% 8%	1600
	11th to 20th	Night	52% 10% 14% 19% 6%	1596
	21st to end	Night	41% 8% 15% 24% 12% 1	1797
September	1st to 10th	Night	42% 8% 11% 26% 13% 1	1800
	11th to 20th	Night	44% 5% 12% 23% 15% 1	1970
	21st to end	Night	45% 5% 10% 25% 14% 2	1980
October	1st to 10th	Night	46% 4 10% 24% 14% 1	2150
	11th to 20th	Night	48% 6% 12% 25% 9%	2160
	21st to end	Night	55% 4 10% 18% 12% 1	2448
November	1st to 10th	Night	52% 5% 12% 19% 11% 1	2497
	11th to 20th	Night	53% 5% 12% 18% 10% 1	2660
	21st to end	Night	55% 6% 15% 16% 8%	2660
December	1st to 10th	Night	61% 4 10% 17% 7%	2660
	11th to 20th	Night	62% 5% 9% 16% 9%	3460
	21st to end	Night	58% 5% 11% 18% 6% 2	5236

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	36% 24% 31% 9% 1	180
	11th to 20th	Day	41% 22% 27% 7% 2	169
	21st to end	Day	23% 26% 33% 13% 5%	374
February	1st to 10th	Day	34% 23% 26% 14% 2	340
	11th to 20th	Day	36% 27% 24% 10% 2	336
	21st to end	Day	28% 28% 28% 13% 3	314
March	1st to 10th	Day	29% 28% 29% 11% 2	420
	11th to 20th	Day	31% 24% 31% 11% 2 1	420
	21st to end	Day	38% 22% 25% 11% 3 1	462
April	1st to 10th	Day	43% 25% 21% 7% 3	420
	11th to 20th	Day	36% 26% 24% 10% 3	412
	21st to end	Day	36% 20% 28% 11% 4 1	420
May	1st to 10th	Day	39% 22% 26% 9% 4	423
	11th to 20th	Day	30% 20% 29% 16% 4 1	597
	21st to end	Day	31% 19% 29% 16% 4 1	680
June	1st to 10th	Day	33% 20% 28% 15% 4	630
	11th to 20th	Day	28% 18% 30% 18% 6%	630
	21st to end	Day	33% 15% 26% 20% 7%	630
July	1st to 10th	Day	26% 14% 32% 21% 6% 1	620
	11th to 20th	Day	24% 11% 34% 22% 8% 1	618
	21st to end	Day	21% 15% 39% 19% 5% 1	517
August	1st to 10th	Day	21% 13% 39% 20% 6% 1	446
	11th to 20th	Day	25% 12% 35% 21% 5% 1	439
	21st to end	Day	22% 15% 32% 23% 7% 2	495
September	1st to 10th	Day	16% 17% 39% 20% 6% 1	450
	11th to 20th	Day	27% 17% 26% 20% 6% 2	450
	21st to end	Day	26% 19% 29% 16% 7% 3	450
October	1st to 10th	Day	26% 17% 24% 21% 10% 2	365
	11th to 20th	Day	27% 21% 26% 18% 6% 2	360
	21st to end	Day	31% 21% 28% 15% 4 1	396
November	1st to 10th	Day	32% 19% 28% 14% 5% 2	365
	11th to 20th	Day	34% 23% 23% 15% 5%	370
	21st to end	Day	33% 25% 29% 10% 2 1	370
December	1st to 10th	Day	36% 21% 27% 13% 3	370
	11th to 20th	Day	41% 27% 20% 11% 1	249
	21st to end	Day	35% 28% 26% 9% 1 1	198
January	1st to 10th	Night	30% 22% 26% 19% 2	850
	11th to 20th	Night	31% 22% 26% 17% 4	751
	21st to end	Night	23% 23% 33% 17% 5%	792
February	1st to 10th	Night	29% 22% 30% 17% 2	720
	11th to 20th	Night	30% 25% 25% 17% 2	703
	21st to end	Night	23% 23% 30% 20% 4	592
March	1st to 10th	Night	26% 21% 34% 17% 2	720
	11th to 20th	Night	28% 17% 30% 20% 4	720
	21st to end	Night	26% 21% 31% 15% 6%	792
April	1st to 10th	Night	36% 17% 30% 14% 3	614
	11th to 20th	Night	29% 18% 31% 18% 4	534
	21st to end	Night	32% 17% 29% 16% 6% 1	540
May	1st to 10th	Night	29% 15% 30% 21% 5% 1	540
	11th to 20th	Night	32% 16% 32% 17% 3 1	532
	21st to end	Night	25% 17% 37% 17% 4	583
June	1st to 10th	Night	32% 11% 26% 26% 5%	369
	11th to 20th	Night	24% 13% 28% 29% 6%	360
	21st to end	Night	31% 8% 26% 29% 6%	360
July	1st to 10th	Night	24% 6% 37% 27% 6%	350
	11th to 20th	Night	25% 7% 29% 30% 8%	348
	21st to end	Night	24% 8% 32% 30% 6%	562
August	1st to 10th	Night	18% 9% 33% 32% 8%	538
	11th to 20th	Night	26% 8% 28% 31% 8% 1	532
	21st to end	Night	19% 11% 27% 30% 12%	594
September	1st to 10th	Night	21% 10% 36% 25% 8% 1	540
	11th to 20th	Night	26% 11% 23% 26% 13% 1	710
	21st to end	Night	26% 13% 27% 24% 10%	720
October	1st to 10th	Night	25% 12% 26% 27% 10% 1	720
	11th to 20th	Night	24% 16% 31% 19% 9% 1	720
	21st to end	Night	31% 19% 27% 20% 3	792
November	1st to 10th	Night	31% 18% 25% 19% 7% 1	782
	11th to 20th	Night	29% 20% 26% 18% 6% 1	850
	21st to end	Night	30% 23% 25% 19% 4	850
December	1st to 10th	Night	34% 19% 27% 16% 3	850
	11th to 20th	Night	35% 23% 26% 13% 2	850
	21st to end	Night	33% 23% 24% 16% 4	935

Page generated at 2024-01-09 17:24:23. Version ac07

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