Keaton Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Keaton Beach clear sky chart from 2005-11-06 to 2024-02-15.

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	9% 5% 2 5% 5% 3 5% 5% 7% 9% 44%	78786
	Night	9% 6% 2 5% 5% 3 5% 5% 6% 9% 45%	80287
Transparency	Day	36% 9% 15% 18% 15% 7%	78509
	Night	35% 7% 14% 19% 16% 8%	80083
Seeing	Day	10% 7% 21% 27% 24% 12%	14133
	Night	10% 5% 19% 32% 26% 7%	24246

By Month

Percentage Cloud Cover SE (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	14% 7% 2 5% 4 3 4 5% 5% 7% 45%	2836
	11th to 20th	Day	15% 7% 3 6% 5% 2 5% 5% 5% 7% 40%	2840
	21st to end	Day	12% 7% 3 7% 6% 3 4 4 5% 6% 44%	3424
February	1st to 10th	Day	16% 6% 3 6% 5% 3 3 3 5% 6% 44%	1900
	11th to 20th	Day	13% 5% 2 5% 4 3 3 4 4 6% 51%	1788
	21st to end	Day	13% 6% 2 5% 4 3 4 5% 5% 6% 46%	1480
March	1st to 10th	Day	7% 4 2 4 4 2 4 4 5% 9% 55%	1926
	11th to 20th	Day	9% 4 2 4 4 3 4 5% 5% 8% 52%	1980
	21st to end	Day	8% 4 2 4 4 2 3 5% 5% 7% 55%	2178
April	1st to 10th	Day	7% 4 2 4 5% 3 5% 5% 6% 9% 51%	1980
	11th to 20th	Day	10% 5% 2 5% 5% 3 4 4 5% 8% 49%	2012
	21st to end	Day	5% 3 1 4 3 2 3 4 5% 9% 62%	2258
May	1st to 10th	Day	5% 2 1 2 3 2 3 4 6% 8% 64%	2340
	11th to 20th	Day	6% 4 2 4 4 3 4 6% 8% 10% 49%	2301
	21st to end	Day	6% 3 2 4 5% 3 5% 5% 7% 11% 48%	2531
June	1st to 10th	Day	8% 6% 2 6% 6% 4 6% 6% 8% 11% 37%	2340
	11th to 20th	Day	6% 3 2 5% 6% 3 6% 8% 10% 15% 36%	2340
	21st to end	Day	8% 4 3 6% 6% 4 6% 7% 9% 13% 35%	2340
July	1st to 10th	Day	9% 4 2 5% 6% 4 8% 8% 10% 14% 31%	2340
	11th to 20th	Day	6% 5% 3 7% 7% 5% 8% 10% 9% 15% 27%	2340
	21st to end	Day	6% 4 3 6% 7% 4 7% 7% 9% 13% 32%	2547
August	1st to 10th	Day	10% 3 1 4 6% 5% 7% 8% 10% 12% 33%	2258
	11th to 20th	Day	10% 5% 3 7% 6% 5% 7% 7% 10% 12% 28%	2125
	21st to end	Day	9% 6% 2 7% 8% 3 6% 8% 9% 11% 31%	2286
September	1st to 10th	Day	7% 6% 3 7% 7% 5% 7% 8% 9% 13% 28%	1980
	11th to 20th	Day	8% 4 3 7% 7% 4 6% 7% 9% 12% 33%	1980
	21st to end	Day	7% 5% 3 6% 5% 4 5% 6% 6% 9% 45%	1980
October	1st to 10th	Day	7% 5% 2 5% 6% 2 4 5% 7% 9% 47%	1980
	11th to 20th	Day	5% 3 2 3 4 3 4 3 5% 7% 61%	1895
	21st to end	Day	7% 3 1 5% 4 3 5% 5% 6% 7% 55%	1980
November	1st to 10th	Day	8% 4 2 4 3 2 4 4 6% 9% 55%	1857
	11th to 20th	Day	10% 5% 2 4 3 2 4 3 6% 6% 55%	1747
	21st to end	Day	9% 5% 2 4 4 2 5% 5% 5% 8% 51%	1710
December	1st to 10th	Day	11% 6% 2 5% 5% 3 4 4 6% 7% 47%	1710
	11th to 20th	Day	13% 7% 2 5% 5% 3 4 4 6% 7% 44%	2153
	21st to end	Day	19% 8% 3 5% 4 2 4 4 4 6% 41%	3124
January	1st to 10th	Night	15% 8% 3 5% 4 3 4 4 6% 8% 41%	4109
	11th to 20th	Night	11% 8% 3 7% 6% 3 5% 6% 5% 8% 39%	4120
	21st to end	Night	15% 9% 4 7% 4 3 4 4 4 6% 40%	4215
February	1st to 10th	Night	14% 7% 2 5% 5% 3 3 4 5% 7% 45%	2280
	11th to 20th	Night	12% 8% 3 5% 4 2 3 4 5% 7% 48%	2153
	21st to end	Night	12% 8% 3 6% 5% 3 4 5% 4 6% 45%	1776
March	1st to 10th	Night	9% 5% 3 4 3 3 3 3 5% 9% 55%	2033
	11th to 20th	Night	11% 5% 2 4 4 3 4 3 6% 9% 49%	1980
	21st to end	Night	7% 5% 2 5% 4 2 3 3 4 8% 56%	2178
April	1st to 10th	Night	10% 5% 2 5% 5% 3 4 5% 5% 7% 49%	1980
	11th to 20th	Night	8% 4 2 6% 5% 2 5% 5% 5% 9% 49%	1911
	21st to end	Night	5% 3 1 4 3 3 4 4 5% 8% 59%	1702
May	1st to 10th	Night	6% 3 2 3 3 2 4 5% 5% 10% 59%	1620
	11th to 20th	Night	5% 3 2 5% 5% 3 5% 5% 6% 12% 50%	1592
	21st to end	Night	5% 3 2 3 4 2 4 5% 7% 12% 53%	1744
June	1st to 10th	Night	9% 5% 2 6% 6% 3 5% 5% 8% 11% 40%	1620
	11th to 20th	Night	5% 3 2 5% 6% 4 6% 7% 8% 13% 42%	1620
	21st to end	Night	7% 5% 2 6% 6% 3 5% 6% 9% 12% 38%	1620
July	1st to 10th	Night	6% 3 3 4 6% 4 6% 7% 10% 15% 35%	1620
	11th to 20th	Night	4 5% 2 7% 7% 5% 5% 9% 9% 15% 33%	1620
	21st to end	Night	5% 4 2 5% 6% 4 8% 8% 9% 15% 36%	1771
August	1st to 10th	Night	6% 4 2 5% 5% 3 5% 6% 9% 15% 40%	1673
	11th to 20th	Night	5% 5% 2 5% 7% 5% 8% 8% 10% 14% 32%	1776
	21st to end	Night	8% 6% 3 7% 7% 5% 6% 7% 8% 10% 33%	2049
September	1st to 10th	Night	7% 7% 3 6% 7% 5% 6% 7% 10% 13% 29%	1980
	11th to 20th	Night	9% 6% 2 7% 7% 4 8% 7% 8% 11% 31%	1980
	21st to end	Night	8% 5% 2 6% 5% 3 5% 6% 7% 10% 43%	1980
October	1st to 10th	Night	7% 5% 3 6% 5% 4 5% 4 5% 7% 49%	1980
	11th to 20th	Night	6% 4 2 4 4 3 4 4 5% 6% 58%	2064
	21st to end	Night	7% 4 2 4 5% 3 5% 5% 6% 6% 52%	2376
November	1st to 10th	Night	6% 4 2 5% 6% 3 4 5% 5% 7% 53%	2221
	11th to 20th	Night	10% 5% 2 4 4 3 4 4 5% 7% 52%	2430
	21st to end	Night	10% 6% 3 6% 4 3 4 5% 5% 7% 48%	2470
December	1st to 10th	Night	12% 5% 3 5% 5% 3 4 5% 6% 8% 45%	2470
	11th to 20th	Night	12% 6% 3 6% 5% 2 4 4 4 7% 47%	3042
	21st to end	Night	15% 8% 3 5% 5% 3 4 4 5% 7% 41%	4532

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	38% 5% 9% 17% 19% 13%	2837
	11th to 20th	Day	42% 5% 8% 15% 16% 15%	2840
	21st to end	Day	36% 9% 10% 14% 20% 10%	3424
February	1st to 10th	Day	41% 4 11% 13% 19% 12%	1900
	11th to 20th	Day	34% 5% 8% 17% 25% 11%	1798
	21st to end	Day	36% 5% 13% 15% 21% 10%	1480
March	1st to 10th	Day	26% 6% 11% 21% 27% 10%	1926
	11th to 20th	Day	32% 6% 15% 20% 17% 11%	1980
	21st to end	Day	29% 7% 12% 23% 19% 10%	2178
April	1st to 10th	Day	31% 8% 12% 19% 18% 11%	1980
	11th to 20th	Day	35% 6% 8% 22% 21% 8%	2012
	21st to end	Day	22% 7% 12% 27% 23% 9%	2258
May	1st to 10th	Day	20% 7% 11% 28% 25% 10%	2340
	11th to 20th	Day	30% 10% 18% 22% 17% 4	2305
	21st to end	Day	32% 10% 15% 23% 18% 2	2531
June	1st to 10th	Day	39% 13% 21% 20% 6%	2340
	11th to 20th	Day	36% 13% 22% 21% 7%	2340
	21st to end	Day	40% 13% 23% 16% 6% 1	2340
July	1st to 10th	Day	40% 17% 27% 15% 2	2275
	11th to 20th	Day	44% 16% 24% 13% 2	2271
	21st to end	Day	40% 14% 27% 17% 2	2405
August	1st to 10th	Day	41% 16% 24% 16% 2	2245
	11th to 20th	Day	46% 15% 27% 10% 2	2125
	21st to end	Day	46% 15% 20% 14% 4	2286
September	1st to 10th	Day	48% 14% 17% 14% 6% 2	1980
	11th to 20th	Day	43% 14% 20% 13% 9% 2	1980
	21st to end	Day	37% 8% 14% 20% 15% 6%	1980
October	1st to 10th	Day	35% 9% 12% 17% 16% 11%	1980
	11th to 20th	Day	23% 6% 9% 25% 28% 9%	1895
	21st to end	Day	28% 6% 11% 15% 25% 16%	1980
November	1st to 10th	Day	27% 5% 12% 18% 22% 15%	1857
	11th to 20th	Day	30% 5% 8% 19% 26% 11%	1747
	21st to end	Day	32% 5% 9% 22% 23% 8%	1710
December	1st to 10th	Day	36% 5% 12% 22% 18% 7%	1710
	11th to 20th	Day	38% 6% 9% 17% 20% 10%	2150
	21st to end	Day	45% 4 6% 21% 19% 6%	3124
January	1st to 10th	Night	40% 4 8% 13% 19% 16%	4109
	11th to 20th	Night	43% 4 7% 15% 21% 10%	4120
	21st to end	Night	43% 6% 9% 12% 19% 10%	4215
February	1st to 10th	Night	38% 5% 10% 14% 20% 12%	2280
	11th to 20th	Night	36% 4 7% 18% 21% 13%	2154
	21st to end	Night	39% 5% 9% 17% 18% 11%	1776
March	1st to 10th	Night	28% 5% 11% 22% 22% 12%	2033
	11th to 20th	Night	34% 5% 14% 21% 16% 11%	1980
	21st to end	Night	29% 5% 11% 25% 20% 10%	2178
April	1st to 10th	Night	35% 5% 13% 18% 18% 11%	1980
	11th to 20th	Night	32% 7% 8% 25% 22% 7%	1911
	21st to end	Night	22% 5% 13% 28% 24% 8%	1702
May	1st to 10th	Night	23% 5% 12% 28% 23% 10%	1620
	11th to 20th	Night	28% 8% 21% 23% 16% 4	1593
	21st to end	Night	23% 9% 19% 24% 22% 3	1745
June	1st to 10th	Night	37% 10% 21% 25% 7%	1620
	11th to 20th	Night	29% 13% 28% 24% 6%	1620
	21st to end	Night	35% 11% 27% 20% 7% 1	1620
July	1st to 10th	Night	34% 15% 30% 17% 3	1575
	11th to 20th	Night	36% 18% 28% 15% 3	1566
	21st to end	Night	33% 15% 33% 17% 3	1672
August	1st to 10th	Night	30% 16% 34% 17% 4	1662
	11th to 20th	Night	35% 17% 34% 12% 2	1776
	21st to end	Night	43% 14% 23% 17% 3 1	2049
September	1st to 10th	Night	44% 14% 21% 15% 6% 1	1980
	11th to 20th	Night	42% 13% 21% 16% 7% 1	1980
	21st to end	Night	34% 8% 17% 20% 15% 5%	1980
October	1st to 10th	Night	34% 7% 14% 17% 16% 12%	1980
	11th to 20th	Night	26% 5% 10% 24% 27% 8%	2064
	21st to end	Night	30% 5% 10% 16% 24% 15%	2376
November	1st to 10th	Night	31% 4 10% 21% 20% 14%	2221
	11th to 20th	Night	33% 4 8% 18% 23% 14%	2430
	21st to end	Night	35% 5% 11% 19% 20% 10%	2470
December	1st to 10th	Night	36% 6% 11% 23% 17% 7%	2470
	11th to 20th	Night	38% 5% 9% 16% 22% 10%	3044
	21st to end	Night	43% 5% 8% 21% 19% 5%	4532

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	11% 14% 48% 19% 7% 1	270
	11th to 20th	Day	10% 14% 40% 27% 7% 2	270
	21st to end	Day	19% 20% 44% 14% 4	297
February	1st to 10th	Day	17% 17% 37% 21% 9%	270
	11th to 20th	Day	19% 15% 34% 25% 8%	252
	21st to end	Day	12% 14% 45% 22% 8%	198
March	1st to 10th	Day	8% 15% 36% 30% 11%	366
	11th to 20th	Day	15% 11% 32% 27% 13% 1	420
	21st to end	Day	10% 12% 33% 29% 14% 2	462
April	1st to 10th	Day	14% 10% 32% 27% 15% 2	420
	11th to 20th	Day	11% 10% 31% 28% 17% 3	412
	21st to end	Day	7% 5% 30% 34% 19% 5%	420
May	1st to 10th	Day	6% 6% 26% 35% 19% 8%	423
	11th to 20th	Day	7% 3 15% 35% 28% 11%	447
	21st to end	Day	9% 3 10% 27% 34% 17%	485
June	1st to 10th	Day	11% 2 12% 30% 30% 15%	450
	11th to 20th	Day	8% 3 12% 20% 33% 23%	450
	21st to end	Day	6% 2 7% 26% 35% 25%	450
July	1st to 10th	Day	8% 1 7% 21% 33% 30%	445
	11th to 20th	Day	6% 2 4 18% 39% 32%	444
	21st to end	Day	7% 2 5% 23% 39% 25%	488
August	1st to 10th	Day	11% 3 6% 18% 35% 27%	446
	11th to 20th	Day	10% 3 3 16% 41% 28%	439
	21st to end	Day	8% 2 6% 24% 37% 23%	495
September	1st to 10th	Day	8% 4 9% 21% 34% 24%	450
	11th to 20th	Day	9% 2 11% 30% 33% 15%	450
	21st to end	Day	8% 3 12% 26% 36% 14%	450
October	1st to 10th	Day	9% 4 22% 33% 25% 7%	450
	11th to 20th	Day	5% 4 20% 34% 27% 10%	450
	21st to end	Day	8% 5% 22% 40% 22% 4	495
November	1st to 10th	Day	11% 7% 22% 39% 16% 5%	455
	11th to 20th	Day	12% 8% 31% 35% 12% 2	307
	21st to end	Day	10% 9% 38% 33% 9% 1	270
December	1st to 10th	Day	12% 12% 34% 29% 9% 4	270
	11th to 20th	Day	17% 11% 34% 30% 7% 1	270
	21st to end	Day	15% 10% 35% 25% 12% 2	297
January	1st to 10th	Night	16% 10% 34% 28% 11% 1	760
	11th to 20th	Night	11% 9% 29% 35% 15% 1	760
	21st to end	Night	19% 10% 34% 29% 8%	836
February	1st to 10th	Night	17% 9% 28% 33% 12%	760
	11th to 20th	Night	18% 9% 31% 30% 11% 1	722
	21st to end	Night	15% 8% 27% 42% 8%	592
March	1st to 10th	Night	11% 8% 29% 39% 13% 1	720
	11th to 20th	Night	14% 8% 22% 36% 20% 1	720
	21st to end	Night	9% 8% 29% 37% 17% 1	792
April	1st to 10th	Night	12% 8% 22% 39% 18% 1	720
	11th to 20th	Night	8% 8% 25% 38% 19% 1	669
	21st to end	Night	6% 4 24% 39% 25% 2	540
May	1st to 10th	Night	6% 4 20% 40% 26% 4	540
	11th to 20th	Night	6% 2 16% 36% 35% 5%	531
	21st to end	Night	5% 2 8% 34% 44% 7%	584
June	1st to 10th	Night	9% 3 7% 32% 40% 9%	540
	11th to 20th	Night	4 3 6% 29% 39% 19%	540
	21st to end	Night	8% 2 5% 21% 44% 20%	540
July	1st to 10th	Night	5% 2 3 16% 45% 28%	525
	11th to 20th	Night	4 1 2 15% 44% 33%	522
	21st to end	Night	5% 1 2 13% 53% 25%	591
August	1st to 10th	Night	4 2 2 15% 51% 26%	537
	11th to 20th	Night	5% 2 3 11% 53% 27%	534
	21st to end	Night	9% 3 6% 23% 40% 19%	663
September	1st to 10th	Night	9% 3 7% 22% 42% 18%	720
	11th to 20th	Night	9% 3 9% 29% 41% 10%	720
	21st to end	Night	10% 3 11% 29% 39% 8%	720
October	1st to 10th	Night	10% 3 20% 37% 27% 4	720
	11th to 20th	Night	7% 4 17% 39% 31% 3	720
	21st to end	Night	10% 3 20% 41% 24% 2	792
November	1st to 10th	Night	9% 6% 28% 36% 20% 2	740
	11th to 20th	Night	13% 7% 26% 36% 17% 2	760
	21st to end	Night	12% 6% 28% 38% 16%	760
December	1st to 10th	Night	14% 6% 25% 34% 19% 2	760
	11th to 20th	Night	14% 7% 30% 31% 16% 1	760
	21st to end	Night	15% 9% 26% 34% 16%	836

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