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 2026-07-31.

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% 4 4 5% 4 7% 10% 45%	138222
	Night	9% 5% 2 6% 4 4 5% 4 6% 9% 45%	134774
Transparency	Day	22% 39% 11% 13% 10% 4	142021
	Night	23% 37% 10% 13% 11% 5%	139047
Seeing	Day	9% 7% 22% 28% 22% 11%	17480
	Night	10% 6% 20% 32% 26% 7%	27463

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	11% 6% 2 6% 3 4 4 3 4 6% 51%	5258
	11th to 20th	Day	17% 7% 3 7% 4 4 4 4 5% 7% 38%	5280
	21st to end	Day	9% 6% 2 6% 4 4 4 4 5% 9% 48%	6356
February	1st to 10th	Day	14% 8% 2 7% 5% 3 3 3 5% 6% 44%	2100
	11th to 20th	Day	14% 6% 2 6% 3 3 4 3 5% 6% 49%	2048
	21st to end	Day	13% 7% 2 5% 4 4 4 3 5% 5% 48%	1730
March	1st to 10th	Day	15% 6% 2 5% 4 3 4 3 5% 9% 43%	4909
	11th to 20th	Day	8% 5% 2 4 3 3 4 3 5% 7% 55%	5090
	21st to end	Day	12% 4 1 4 3 3 4 3 5% 8% 52%	5586
April	1st to 10th	Day	7% 5% 1 5% 4 4 4 4 6% 8% 50%	2310
	11th to 20th	Day	9% 5% 2 5% 4 4 3 3 6% 7% 52%	2352
	21st to end	Day	5% 3 1 4 3 3 3 3 4 9% 62%	2635
May	1st to 10th	Day	9% 5% 2 6% 4 4 5% 4 6% 9% 46%	7616
	11th to 20th	Day	10% 4 2 5% 3 3 4 4 6% 9% 51%	7626
	21st to end	Day	3 3 1 4 4 4 5% 4 8% 13% 49%	8391
June	1st to 10th	Day	8% 5% 2 7% 5% 5% 6% 5% 8% 11% 38%	2730
	11th to 20th	Day	6% 3 2 6% 5% 4 6% 7% 10% 14% 37%	2730
	21st to end	Day	7% 4 2 6% 5% 5% 6% 7% 10% 12% 35%	2730
July	1st to 10th	Day	7% 3 1 5% 5% 6% 8% 7% 12% 16% 29%	6030
	11th to 20th	Day	3 2 1 5% 4 5% 7% 6% 9% 14% 42%	6030
	21st to end	Day	4 3 2 5% 5% 5% 7% 7% 11% 15% 35%	6554
August	1st to 10th	Day	11% 3 2 5% 5% 6% 6% 6% 9% 12% 33%	4105
	11th to 20th	Day	6% 4 2 5% 4 5% 5% 5% 8% 12% 45%	3849
	21st to end	Day	8% 5% 2 7% 6% 5% 6% 6% 8% 11% 37%	4147
September	1st to 10th	Day	8% 7% 3 8% 6% 7% 7% 5% 9% 12% 29%	2200
	11th to 20th	Day	8% 5% 2 8% 6% 6% 6% 6% 9% 12% 34%	2200
	21st to end	Day	7% 5% 2 6% 4 5% 5% 4 6% 9% 45%	2200
October	1st to 10th	Day	8% 5% 2 7% 5% 4 4 4 7% 9% 46%	2200
	11th to 20th	Day	5% 3 2 3 3 4 3 3 5% 7% 63%	2105
	21st to end	Day	6% 3 1 5% 4 4 4 3 5% 7% 56%	2200
November	1st to 10th	Day	8% 4 1 4 3 3 4 4 6% 8% 55%	2057
	11th to 20th	Day	9% 5% 2 4 3 3 4 3 6% 6% 56%	1930
	21st to end	Day	9% 5% 2 4 4 4 4 3 5% 8% 52%	1890
December	1st to 10th	Day	8% 5% 2 5% 3 4 4 4 5% 6% 54%	3020
	11th to 20th	Day	10% 6% 2 5% 3 3 3 3 5% 6% 53%	3463
	21st to end	Day	17% 7% 3 6% 3 3 3 3 4 6% 45%	4565
January	1st to 10th	Night	9% 6% 2 6% 3 3 3 3 5% 8% 53%	7635
	11th to 20th	Night	16% 6% 3 8% 5% 4 5% 4 5% 7% 37%	7680
	21st to end	Night	15% 7% 3 6% 3 3 4 3 5% 8% 41%	7808
February	1st to 10th	Night	13% 7% 3 6% 4 3 3 3 5% 6% 46%	2520
	11th to 20th	Night	13% 9% 2 6% 4 3 3 3 4 7% 46%	2458
	21st to end	Night	11% 8% 3 6% 3 3 4 4 4 6% 48%	2076
March	1st to 10th	Night	14% 8% 3 7% 4 4 4 3 4 6% 42%	5150
	11th to 20th	Night	7% 5% 2 4 3 3 4 3 6% 9% 54%	5090
	21st to end	Night	11% 5% 2 5% 4 3 4 3 5% 7% 50%	5588
April	1st to 10th	Night	10% 6% 2 6% 5% 4 3 5% 6% 7% 47%	2310
	11th to 20th	Night	7% 4 2 6% 4 3 4 3 6% 8% 53%	2232
	21st to end	Night	5% 3 2 4 4 4 4 4 5% 9% 57%	1985
May	1st to 10th	Night	7% 4 2 6% 4 4 5% 4 6% 10% 49%	5237
	11th to 20th	Night	11% 4 2 6% 4 4 4 4 6% 9% 48%	5234
	21st to end	Night	3 2 1 5% 4 4 4 4 8% 13% 52%	5761
June	1st to 10th	Night	8% 6% 2 7% 5% 5% 5% 4 8% 12% 39%	1890
	11th to 20th	Night	5% 4 2 5% 5% 6% 6% 5% 9% 13% 41%	1890
	21st to end	Night	6% 6% 2 6% 5% 5% 5% 6% 10% 12% 39%	1890
July	1st to 10th	Night	6% 4 2 7% 8% 7% 8% 8% 12% 15% 24%	4148
	11th to 20th	Night	3 3 1 5% 4 4 5% 6% 9% 15% 45%	4147
	21st to end	Night	5% 4 2 6% 5% 5% 7% 6% 11% 16% 34%	4517
August	1st to 10th	Night	8% 4 2 7% 5% 5% 6% 5% 9% 14% 35%	3037
	11th to 20th	Night	3 3 1 4 4 4 6% 5% 9% 14% 46%	3200
	21st to end	Night	7% 6% 3 8% 6% 6% 7% 6% 9% 12% 31%	3715
September	1st to 10th	Night	8% 7% 3 7% 6% 6% 6% 6% 9% 12% 29%	2200
	11th to 20th	Night	9% 6% 2 7% 5% 6% 7% 6% 8% 11% 33%	2200
	21st to end	Night	8% 5% 2 7% 4 4 5% 5% 7% 9% 45%	2200
October	1st to 10th	Night	7% 5% 3 6% 5% 5% 4 4 5% 7% 47%	2200
	11th to 20th	Night	6% 4 2 4 3 4 4 3 5% 6% 60%	2294
	21st to end	Night	7% 4 2 5% 4 4 5% 3 7% 6% 54%	2640
November	1st to 10th	Night	6% 4 2 6% 4 5% 4 4 5% 8% 52%	2461
	11th to 20th	Night	10% 5% 2 5% 4 3 3 3 5% 6% 53%	2686
	21st to end	Night	9% 7% 2 6% 4 3 4 4 5% 7% 49%	2730
December	1st to 10th	Night	10% 5% 2 5% 4 4 3 3 5% 7% 53%	4380
	11th to 20th	Night	9% 6% 3 6% 3 3 4 3 4 7% 52%	4952
	21st to end	Night	13% 7% 3 6% 4 4 4 3 6% 7% 43%	6633

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	26% 23% 7% 13% 22% 9%	5259
	11th to 20th	Day	39% 22% 4 10% 13% 12%	5280
	21st to end	Day	23% 26% 10% 16% 15% 10%	6356
February	1st to 10th	Day	15% 59% 4 7% 8% 6%	2100
	11th to 20th	Day	14% 59% 4 10% 10% 2	2058
	21st to end	Day	14% 59% 5% 6% 10% 6%	1730
March	1st to 10th	Day	32% 31% 8% 11% 13% 6%	4909
	11th to 20th	Day	19% 31% 7% 11% 17% 14%	5090
	21st to end	Day	22% 30% 7% 20% 13% 8%	5586
April	1st to 10th	Day	13% 61% 6% 9% 6% 4	2310
	11th to 20th	Day	12% 60% 3 8% 12% 5%	2352
	21st to end	Day	10% 60% 6% 13% 8% 3	2635
May	1st to 10th	Day	30% 29% 13% 16% 9% 3	7651
	11th to 20th	Day	24% 26% 13% 24% 11% 2	7630
	21st to end	Day	20% 30% 21% 18% 10% 1	8405
June	1st to 10th	Day	17% 63% 9% 8% 2	2730
	11th to 20th	Day	15% 65% 10% 7% 2	2730
	21st to end	Day	12% 64% 11% 10% 3	2730
July	1st to 10th	Day	31% 39% 25% 5%	5965
	11th to 20th	Day	19% 36% 32% 12% 1	5961
	21st to end	Day	26% 37% 19% 17%	6370
August	1st to 10th	Day	27% 44% 14% 11% 3	4092
	11th to 20th	Day	14% 43% 18% 17% 8%	3885
	21st to end	Day	22% 44% 16% 15% 2	4147
September	1st to 10th	Day	20% 60% 9% 6% 4 1	2200
	11th to 20th	Day	15% 60% 9% 10% 6%	2200
	21st to end	Day	15% 59% 8% 11% 6% 1	2200
October	1st to 10th	Day	33% 39% 5% 7% 11% 4	3590
	11th to 20th	Day	5% 35% 3 12% 27% 18%	3410
	21st to end	Day	8% 36% 4 17% 27% 7%	3538
November	1st to 10th	Day	14% 54% 7% 9% 9% 6%	2057
	11th to 20th	Day	15% 55% 4 8% 12% 6%	1930
	21st to end	Day	14% 55% 4 11% 10% 5%	1890
December	1st to 10th	Day	19% 36% 7% 10% 19% 10%	3020
	11th to 20th	Day	21% 33% 5% 16% 18% 7%	3460
	21st to end	Day	33% 28% 5% 14% 18% 2	4565
January	1st to 10th	Night	24% 22% 7% 14% 23% 10%	7636
	11th to 20th	Night	41% 21% 4 12% 13% 9%	7680
	21st to end	Night	32% 24% 7% 15% 15% 7%	7808
February	1st to 10th	Night	16% 60% 3 7% 9% 5%	2520
	11th to 20th	Night	16% 58% 5% 10% 8% 3	2459
	21st to end	Night	14% 60% 5% 7% 9% 5%	2076
March	1st to 10th	Night	36% 30% 5% 11% 11% 6%	5150
	11th to 20th	Night	19% 29% 7% 14% 16% 14%	5090
	21st to end	Night	27% 29% 5% 16% 15% 8%	5588
April	1st to 10th	Night	15% 60% 5% 9% 6% 5%	2310
	11th to 20th	Night	11% 60% 2 10% 10% 6%	2232
	21st to end	Night	11% 60% 5% 12% 9% 3	1985
May	1st to 10th	Night	27% 28% 14% 20% 7% 4	5264
	11th to 20th	Night	27% 26% 13% 20% 12% 2	5235
	21st to end	Night	18% 29% 21% 23% 9%	5771
June	1st to 10th	Night	16% 62% 10% 9% 3	1890
	11th to 20th	Night	14% 64% 13% 7% 2	1890
	21st to end	Night	12% 61% 13% 10% 3	1890
July	1st to 10th	Night	37% 36% 23% 4	4105
	11th to 20th	Night	16% 34% 38% 11%	4096
	21st to end	Night	27% 33% 25% 14% 1	4387
August	1st to 10th	Night	26% 42% 19% 10% 3	3026
	11th to 20th	Night	11% 42% 22% 20% 5%	3230
	21st to end	Night	26% 43% 18% 10% 3	3715
September	1st to 10th	Night	20% 61% 8% 6% 4 1	2200
	11th to 20th	Night	16% 61% 10% 9% 4 1	2200
	21st to end	Night	14% 58% 9% 11% 7% 1	2200
October	1st to 10th	Night	36% 39% 6% 8% 8% 3	3590
	11th to 20th	Night	8% 36% 3 14% 22% 17%	3728
	21st to end	Night	8% 36% 4 17% 27% 8%	4252
November	1st to 10th	Night	17% 54% 6% 10% 6% 6%	2461
	11th to 20th	Night	16% 55% 5% 9% 10% 6%	2686
	21st to end	Night	16% 55% 5% 9% 10% 6%	2730
December	1st to 10th	Night	22% 35% 5% 10% 14% 14%	4380
	11th to 20th	Night	22% 34% 7% 13% 16% 8%	4954
	21st to end	Night	33% 28% 6% 14% 15% 4	6633

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% 50% 19% 6% 1	330
	11th to 20th	Day	12% 16% 40% 25% 6% 2	330
	21st to end	Day	17% 21% 43% 15% 4	363
February	1st to 10th	Day	14% 16% 39% 22% 8% 1	330
	11th to 20th	Day	20% 17% 34% 23% 6%	330
	21st to end	Day	12% 17% 45% 19% 7%	273
March	1st to 10th	Day	11% 15% 34% 28% 11%	477
	11th to 20th	Day	14% 13% 33% 27% 12% 1	540
	21st to end	Day	10% 12% 32% 30% 14% 1	594
April	1st to 10th	Day	13% 11% 33% 27% 14% 2	540
	11th to 20th	Day	10% 10% 32% 29% 17% 3	532
	21st to end	Day	5% 6% 29% 35% 19% 5%	540
May	1st to 10th	Day	6% 8% 27% 34% 18% 6%	543
	11th to 20th	Day	8% 4 21% 34% 25% 9%	567
	21st to end	Day	7% 4 14% 31% 29% 15%	617
June	1st to 10th	Day	10% 3 15% 32% 27% 13%	570
	11th to 20th	Day	7% 3 15% 23% 31% 20%	570
	21st to end	Day	5% 2 7% 28% 34% 24%	570
July	1st to 10th	Day	7% 2 7% 22% 33% 29%	565
	11th to 20th	Day	5% 2 4 22% 37% 30%	564
	21st to end	Day	6% 1 6% 25% 37% 25%	616
August	1st to 10th	Day	11% 3 8% 19% 33% 26%	526
	11th to 20th	Day	9% 2 3 18% 40% 27%	519
	21st to end	Day	8% 2 7% 26% 37% 21%	583
September	1st to 10th	Day	9% 5% 12% 22% 31% 22%	530
	11th to 20th	Day	9% 2 12% 32% 31% 14%	530
	21st to end	Day	8% 4 12% 27% 34% 14%	530
October	1st to 10th	Day	10% 5% 23% 34% 23% 6%	530
	11th to 20th	Day	5% 4 23% 32% 27% 9%	530
	21st to end	Day	8% 5% 22% 42% 20% 3	583
November	1st to 10th	Day	10% 7% 21% 39% 18% 4	535
	11th to 20th	Day	10% 8% 32% 34% 14% 2	370
	21st to end	Day	9% 10% 39% 30% 10% 1	330
December	1st to 10th	Day	14% 14% 35% 26% 8% 3	330
	11th to 20th	Day	15% 10% 36% 29% 9% 1	330
	21st to end	Day	14% 9% 38% 24% 12% 2	363
January	1st to 10th	Night	15% 11% 34% 29% 10% 1	840
	11th to 20th	Night	12% 9% 30% 34% 14% 1	840
	21st to end	Night	19% 10% 34% 30% 7%	924
February	1st to 10th	Night	17% 8% 28% 35% 12%	840
	11th to 20th	Night	18% 9% 31% 30% 10% 1	823
	21st to end	Night	14% 10% 30% 40% 7%	692
March	1st to 10th	Night	13% 8% 29% 38% 12% 1	840
	11th to 20th	Night	13% 9% 23% 36% 18% 1	840
	21st to end	Night	9% 8% 28% 38% 16% 1	924
April	1st to 10th	Night	12% 9% 24% 37% 17% 1	840
	11th to 20th	Night	8% 8% 25% 39% 19% 1	780
	21st to end	Night	6% 3 23% 40% 26% 2	630
May	1st to 10th	Night	6% 4 20% 41% 25% 4	630
	11th to 20th	Night	8% 3 16% 37% 32% 4	621
	21st to end	Night	5% 2 9% 34% 43% 7%	683
June	1st to 10th	Night	8% 3 9% 33% 39% 8%	630
	11th to 20th	Night	4 3 7% 28% 40% 17%	630
	21st to end	Night	7% 2 5% 20% 46% 20%	630
July	1st to 10th	Night	5% 2 4 16% 45% 28%	615
	11th to 20th	Night	4 1 2 15% 46% 31%	612
	21st to end	Night	5% 2 2 14% 53% 24%	687
August	1st to 10th	Night	5% 3 4 15% 49% 25%	597
	11th to 20th	Night	5% 2 3 12% 54% 26%	594
	21st to end	Night	8% 3 7% 24% 40% 18%	737
September	1st to 10th	Night	10% 3 8% 24% 40% 16%	800
	11th to 20th	Night	9% 3 10% 31% 39% 9%	800
	21st to end	Night	11% 3 11% 30% 39% 8%	800
October	1st to 10th	Night	11% 4 21% 37% 25% 3	800
	11th to 20th	Night	6% 4 18% 39% 30% 2	800
	21st to end	Night	10% 4 21% 42% 23% 2	880
November	1st to 10th	Night	8% 6% 26% 37% 21% 2	820
	11th to 20th	Night	12% 7% 25% 37% 17% 2	840
	21st to end	Night	12% 7% 28% 36% 17%	840
December	1st to 10th	Night	14% 7% 26% 35% 17% 1	840
	11th to 20th	Night	13% 6% 30% 33% 16% 1	840
	21st to end	Night	14% 9% 26% 35% 15%	924

Page generated at 2026-07-28 03:25:26. Version ac07

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