Wright Brothers National Memorial
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wright Brothers National Memorial clear sky chart from 2005-11-06 to 2026-10-14.

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	11% 6% 2 6% 4 4 5% 4 6% 8% 42%	148463
	Night	12% 7% 2 6% 4 4 5% 4 6% 8% 42%	143254
Transparency	Day	38% 7% 14% 23% 15% 3	152055
	Night	39% 6% 13% 21% 17% 4	147733
Seeing	Day	14% 7% 21% 28% 22% 7%	18015
	Night	16% 7% 22% 31% 20% 4	27546

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	9% 6% 3 6% 3 3 4 3 4 6% 53%	4938
	11th to 20th	Day	14% 5% 2 5% 4 4 3 3 4 5% 53%	5280
	21st to end	Day	14% 13% 3 7% 4 4 4 3 5% 6% 37%	5780
February	1st to 10th	Day	13% 8% 3 7% 5% 4 4 3 5% 7% 41%	1936
	11th to 20th	Day	19% 8% 3 6% 5% 4 3 3 5% 4 41%	2048
	21st to end	Day	15% 7% 2 5% 5% 3 5% 4 5% 6% 42%	1730
March	1st to 10th	Day	17% 8% 2 6% 4 3 4 3 5% 6% 41%	4760
	11th to 20th	Day	9% 5% 2 6% 4 4 4 3 4 6% 53%	5090
	21st to end	Day	11% 7% 2 5% 3 4 4 3 5% 7% 50%	5838
April	1st to 10th	Day	11% 6% 2 5% 4 4 4 3 5% 6% 51%	2520
	11th to 20th	Day	8% 5% 2 5% 4 4 3 4 6% 8% 52%	2494
	21st to end	Day	10% 5% 2 5% 4 4 4 3 6% 9% 50%	2520
May	1st to 10th	Day	11% 6% 3 7% 5% 5% 5% 4 7% 9% 39%	7021
	11th to 20th	Day	12% 7% 2 6% 4 4 5% 3 5% 8% 43%	7577
	21st to end	Day	10% 7% 3 8% 5% 5% 5% 4 6% 8% 39%	9045
June	1st to 10th	Day	8% 5% 2 6% 5% 4 5% 4 8% 11% 42%	2940
	11th to 20th	Day	8% 5% 2 5% 4 5% 5% 4 7% 11% 44%	2940
	21st to end	Day	5% 4 2 6% 5% 4 5% 5% 9% 12% 43%	2940
July	1st to 10th	Day	7% 5% 2 5% 5% 5% 6% 5% 8% 12% 39%	8280
	11th to 20th	Day	8% 6% 3 8% 5% 5% 5% 5% 8% 12% 34%	7867
	21st to end	Day	11% 6% 3 7% 5% 5% 6% 5% 8% 10% 33%	8340
August	1st to 10th	Day	11% 9% 4 8% 5% 6% 6% 5% 8% 12% 27%	5766
	11th to 20th	Day	7% 5% 2 6% 4 5% 5% 5% 7% 12% 42%	5488
	21st to end	Day	9% 6% 2 7% 5% 5% 5% 4 7% 9% 40%	6080
September	1st to 10th	Day	11% 6% 2 6% 4 5% 5% 4 7% 9% 42%	2520
	11th to 20th	Day	12% 6% 2 7% 5% 5% 5% 4 5% 7% 40%	2500
	21st to end	Day	18% 7% 3 8% 5% 5% 4 4 5% 7% 35%	2304
October	1st to 10th	Day	15% 6% 2 6% 4 3 4 3 5% 6% 46%	2100
	11th to 20th	Day	15% 7% 2 5% 4 4 3 2 5% 5% 48%	2030
	21st to end	Day	12% 6% 2 5% 4 4 4 4 6% 6% 49%	2200
November	1st to 10th	Day	17% 5% 2 5% 4 4 4 4 5% 5% 44%	1934
	11th to 20th	Day	14% 6% 2 4 4 4 3 3 5% 7% 47%	1890
	21st to end	Day	12% 6% 3 6% 4 3 4 4 5% 7% 47%	1890
December	1st to 10th	Day	12% 6% 2 5% 4 4 4 3 5% 6% 50%	2759
	11th to 20th	Day	13% 9% 2 7% 6% 4 5% 4 6% 5% 39%	3070
	21st to end	Day	12% 6% 2 5% 4 4 4 4 5% 8% 46%	4048
January	1st to 10th	Night	11% 6% 3 5% 4 3 4 3 5% 7% 49%	7951
	11th to 20th	Night	11% 5% 2 5% 4 4 3 3 5% 5% 53%	7680
	21st to end	Night	15% 8% 3 8% 4 4 4 3 5% 5% 41%	8401
February	1st to 10th	Night	17% 8% 2 6% 4 3 3 3 6% 7% 41%	2683
	11th to 20th	Night	19% 8% 3 6% 4 4 4 3 5% 7% 39%	2458
	21st to end	Night	15% 8% 3 7% 4 4 4 3 5% 6% 43%	2076
March	1st to 10th	Night	17% 8% 3 7% 5% 4 4 3 4 5% 39%	5309
	11th to 20th	Night	14% 6% 2 6% 3 4 3 4 5% 5% 48%	5090
	21st to end	Night	14% 7% 3 6% 4 3 3 3 4 5% 48%	5336
April	1st to 10th	Night	12% 5% 2 6% 4 4 4 3 5% 8% 46%	2100
	11th to 20th	Night	9% 7% 3 6% 3 3 4 4 6% 8% 49%	2075
	21st to end	Night	11% 6% 2 6% 5% 4 4 2 5% 7% 48%	2100
May	1st to 10th	Night	9% 7% 3 9% 5% 5% 6% 5% 7% 10% 35%	5833
	11th to 20th	Night	14% 7% 3 6% 4 4 4 4 6% 7% 41%	5305
	21st to end	Night	12% 9% 4 9% 5% 4 5% 4 6% 8% 35%	5108
June	1st to 10th	Night	10% 6% 2 5% 5% 5% 4 5% 6% 9% 42%	1680
	11th to 20th	Night	8% 5% 2 5% 4 4 5% 6% 8% 11% 41%	1680
	21st to end	Night	7% 4 2 5% 5% 5% 5% 4 8% 12% 43%	1680
July	1st to 10th	Night	7% 4 2 5% 4 4 6% 5% 7% 12% 44%	4678
	11th to 20th	Night	8% 6% 3 7% 5% 6% 6% 5% 9% 13% 32%	5071
	21st to end	Night	13% 6% 3 7% 6% 6% 6% 5% 8% 10% 31%	5736
August	1st to 10th	Night	10% 7% 3 7% 6% 5% 6% 6% 8% 11% 30%	4323
	11th to 20th	Night	7% 5% 3 7% 6% 6% 6% 5% 7% 10% 39%	4557
	21st to end	Night	10% 6% 3 7% 5% 5% 5% 4 7% 10% 38%	5045
September	1st to 10th	Night	12% 5% 2 5% 5% 4 5% 4 6% 9% 42%	2100
	11th to 20th	Night	14% 8% 2 7% 5% 5% 5% 4 6% 7% 38%	2118
	21st to end	Night	18% 9% 3 8% 4 5% 5% 4 5% 7% 33%	2311
October	1st to 10th	Night	13% 6% 2 5% 4 4 4 3 4 8% 46%	2520
	11th to 20th	Night	16% 7% 2 6% 3 3 3 3 4 5% 49%	2437
	21st to end	Night	12% 6% 2 5% 3 4 4 3 5% 7% 50%	2640
November	1st to 10th	Night	16% 6% 2 6% 5% 4 4 3 6% 6% 42%	2582
	11th to 20th	Night	14% 7% 2 6% 5% 4 4 4 5% 6% 42%	2730
	21st to end	Night	11% 6% 2 5% 4 3 4 3 6% 7% 48%	2730
December	1st to 10th	Night	10% 6% 2 5% 4 3 3 3 4 6% 53%	4636
	11th to 20th	Night	14% 7% 2 8% 5% 5% 5% 4 7% 6% 38%	5345
	21st to end	Night	11% 7% 2 5% 3 4 5% 3 6% 8% 46%	7150

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	33% 4 12% 27% 16% 8%	4939
	11th to 20th	Day	36% 3 5% 17% 33% 7%	5280
	21st to end	Day	49% 5% 6% 20% 16% 4	5780
February	1st to 10th	Day	42% 4 12% 23% 15% 3	1936
	11th to 20th	Day	47% 4 9% 18% 19% 4	2057
	21st to end	Day	42% 6% 10% 21% 16% 4	1730
March	1st to 10th	Day	44% 4 10% 19% 16% 7%	4760
	11th to 20th	Day	33% 4 8% 19% 25% 11%	5090
	21st to end	Day	35% 4 14% 23% 18% 5%	5838
April	1st to 10th	Day	33% 5% 16% 22% 21% 4	2520
	11th to 20th	Day	31% 5% 14% 28% 18% 5%	2494
	21st to end	Day	31% 6% 14% 29% 16% 3	2520
May	1st to 10th	Day	41% 8% 18% 21% 10% 2	7053
	11th to 20th	Day	39% 7% 16% 25% 12%	7581
	21st to end	Day	42% 9% 13% 23% 12% 2	9061
June	1st to 10th	Day	34% 10% 15% 26% 14% 1	2940
	11th to 20th	Day	33% 9% 20% 27% 11%	2940
	21st to end	Day	31% 11% 19% 26% 11% 1	2940
July	1st to 10th	Day	34% 10% 22% 26% 7%	8210
	11th to 20th	Day	41% 11% 23% 19% 6%	7794
	21st to end	Day	44% 10% 14% 21% 10%	8156
August	1st to 10th	Day	49% 10% 26% 12% 3	5753
	11th to 20th	Day	34% 9% 25% 24% 9%	5524
	21st to end	Day	40% 7% 16% 26% 10% 1	6080
September	1st to 10th	Day	36% 9% 17% 21% 14% 2	2520
	11th to 20th	Day	42% 8% 11% 22% 15% 2	2500
	21st to end	Day	47% 7% 12% 19% 12% 1	2304
October	1st to 10th	Day	34% 5% 8% 24% 25% 5%	3360
	11th to 20th	Day	32% 4 5% 23% 23% 12%	3270
	21st to end	Day	24% 3 7% 31% 31% 3	3538
November	1st to 10th	Day	40% 6% 11% 21% 19% 3	1934
	11th to 20th	Day	36% 5% 11% 25% 17% 5%	1890
	21st to end	Day	36% 5% 11% 26% 20% 3	1890
December	1st to 10th	Day	35% 4 9% 27% 22% 2	2759
	11th to 20th	Day	45% 5% 13% 18% 14% 5%	3066
	21st to end	Day	36% 5% 14% 29% 15% 1	4048
January	1st to 10th	Night	36% 4 11% 22% 22% 6%	7952
	11th to 20th	Night	34% 4 7% 19% 29% 8%	7680
	21st to end	Night	45% 4 7% 19% 19% 5%	8401
February	1st to 10th	Night	43% 4 11% 23% 18% 3	2683
	11th to 20th	Night	46% 4 9% 19% 17% 4	2460
	21st to end	Night	42% 5% 9% 20% 18% 6%	2076
March	1st to 10th	Night	48% 4 9% 18% 14% 7%	5309
	11th to 20th	Night	37% 5% 9% 14% 24% 12%	5090
	21st to end	Night	40% 4 11% 25% 15% 6%	5336
April	1st to 10th	Night	37% 6% 13% 19% 21% 4	2100
	11th to 20th	Night	34% 5% 12% 25% 19% 5%	2075
	21st to end	Night	36% 7% 10% 28% 16% 3	2100
May	1st to 10th	Night	43% 8% 17% 22% 9% 1	5863
	11th to 20th	Night	42% 7% 13% 26% 11% 1	5306
	21st to end	Night	46% 9% 11% 19% 13% 1	5115
June	1st to 10th	Night	37% 9% 15% 24% 15% 1	1680
	11th to 20th	Night	33% 11% 19% 26% 12%	1680
	21st to end	Night	33% 9% 20% 25% 12% 1	1680
July	1st to 10th	Night	32% 9% 24% 24% 11%	4640
	11th to 20th	Night	41% 11% 23% 19% 6%	5024
	21st to end	Night	46% 10% 15% 18% 10%	5606
August	1st to 10th	Night	45% 11% 24% 16% 3	4312
	11th to 20th	Night	39% 9% 22% 22% 8%	4587
	21st to end	Night	41% 7% 15% 25% 11% 1	5045
September	1st to 10th	Night	38% 9% 16% 21% 13% 2	2100
	11th to 20th	Night	44% 7% 12% 22% 14% 1	2118
	21st to end	Night	50% 7% 11% 20% 12%	2311
October	1st to 10th	Night	39% 5% 7% 21% 26% 3	4040
	11th to 20th	Night	30% 3 6% 19% 29% 14%	3936
	21st to end	Night	23% 3 7% 31% 30% 5%	4252
November	1st to 10th	Night	41% 5% 10% 21% 19% 3	2582
	11th to 20th	Night	42% 4 10% 20% 19% 5%	2730
	21st to end	Night	35% 4 11% 26% 20% 3	2730
December	1st to 10th	Night	34% 3 8% 20% 29% 5%	4636
	11th to 20th	Night	45% 6% 14% 16% 15% 5%	5348
	21st to end	Night	35% 5% 16% 27% 15% 2	7150

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	13% 18% 33% 29% 7%	270
	11th to 20th	Day	16% 15% 38% 25% 6%	330
	21st to end	Day	20% 14% 32% 27% 7% 1	363
February	1st to 10th	Day	18% 14% 29% 31% 7%	376
	11th to 20th	Day	25% 14% 34% 24% 3	536
	21st to end	Day	19% 10% 35% 27% 8% 1	446
March	1st to 10th	Day	17% 13% 32% 27% 9% 1	540
	11th to 20th	Day	19% 11% 33% 27% 9% 1	540
	21st to end	Day	12% 10% 35% 32% 10% 1	594
April	1st to 10th	Day	14% 11% 31% 30% 12% 1	540
	11th to 20th	Day	9% 6% 32% 33% 16% 3	532
	21st to end	Day	12% 6% 26% 34% 19% 3	540
May	1st to 10th	Day	14% 7% 27% 31% 18% 4	543
	11th to 20th	Day	14% 3 20% 32% 25% 5%	567
	21st to end	Day	15% 3 17% 28% 27% 11%	617
June	1st to 10th	Day	9% 3 15% 34% 29% 9%	570
	11th to 20th	Day	11% 3 13% 30% 32% 13%	570
	21st to end	Day	6% 1 10% 33% 39% 11%	570
July	1st to 10th	Day	10% 2 6% 26% 39% 16%	565
	11th to 20th	Day	8% 1 6% 23% 45% 18%	564
	21st to end	Day	11% 2 9% 27% 37% 15%	620
August	1st to 10th	Day	13% 3 8% 28% 36% 12%	566
	11th to 20th	Day	11% 2 6% 23% 39% 19%	559
	21st to end	Day	13% 2 10% 26% 33% 16%	627
September	1st to 10th	Day	11% 2 13% 28% 30% 16%	570
	11th to 20th	Day	15% 4 13% 28% 31% 8%	570
	21st to end	Day	21% 4 15% 28% 24% 7%	570
October	1st to 10th	Day	21% 4 12% 29% 25% 9%	570
	11th to 20th	Day	19% 7% 21% 27% 23% 4	542
	21st to end	Day	13% 8% 21% 28% 22% 7%	583
November	1st to 10th	Day	16% 9% 21% 33% 16% 6%	470
	11th to 20th	Day	17% 12% 29% 28% 12% 2	430
	21st to end	Day	11% 16% 27% 26% 17% 2	430
December	1st to 10th	Day	21% 12% 36% 22% 8% 1	273
	11th to 20th	Day	16% 13% 35% 25% 10% 1	220
	21st to end	Day	17% 9% 36% 24% 12% 1	242
January	1st to 10th	Night	17% 19% 31% 25% 8%	840
	11th to 20th	Night	17% 15% 28% 30% 8% 1	840
	21st to end	Night	19% 14% 33% 28% 5%	924
February	1st to 10th	Night	20% 9% 34% 30% 6%	840
	11th to 20th	Night	23% 13% 35% 25% 4	823
	21st to end	Night	20% 10% 34% 26% 9%	692
March	1st to 10th	Night	15% 9% 33% 32% 10% 1	840
	11th to 20th	Night	19% 10% 31% 30% 9% 2	840
	21st to end	Night	16% 8% 33% 33% 10% 1	924
April	1st to 10th	Night	15% 8% 31% 34% 11%	840
	11th to 20th	Night	12% 6% 29% 35% 16% 2	831
	21st to end	Night	14% 6% 22% 40% 16% 1	840
May	1st to 10th	Night	13% 7% 24% 37% 17% 2	840
	11th to 20th	Night	16% 4 18% 42% 17% 3	655
	21st to end	Night	13% 2 10% 32% 33% 9%	455
June	1st to 10th	Night	13% 2 12% 38% 30% 5%	420
	11th to 20th	Night	10% 2 10% 37% 33% 7%	420
	21st to end	Night	8% 1 6% 38% 41% 5%	420
July	1st to 10th	Night	6% 1 9% 31% 46% 8%	410
	11th to 20th	Night	8% 6% 27% 43% 16%	540
	21st to end	Night	9% 1 8% 32% 41% 8%	690
August	1st to 10th	Night	13% 2 6% 31% 41% 6%	711
	11th to 20th	Night	10% 2 7% 28% 40% 12%	830
	21st to end	Night	15% 2 7% 26% 38% 12%	924
September	1st to 10th	Night	14% 3 9% 25% 35% 14%	840
	11th to 20th	Night	18% 3 11% 28% 34% 6%	840
	21st to end	Night	21% 5% 11% 29% 28% 5%	840
October	1st to 10th	Night	15% 3 16% 28% 29% 9%	840
	11th to 20th	Night	18% 9% 20% 31% 19% 3	813
	21st to end	Night	14% 8% 24% 26% 22% 5%	880
November	1st to 10th	Night	19% 6% 22% 31% 17% 5%	820
	11th to 20th	Night	18% 10% 27% 29% 15% 2	840
	21st to end	Night	13% 14% 24% 30% 17% 2	840
December	1st to 10th	Night	19% 12% 30% 27% 11%	840
	11th to 20th	Night	17% 10% 32% 30% 11%	840
	21st to end	Night	16% 13% 29% 32% 10% 1	924

Page generated at 2026-10-11 05:06:32. Version ac07

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