Dogwood Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dogwood Observatory clear sky chart from 2005-11-06 to 2026-02-16.

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% 7% 2 6% 4 4 4 4 5% 7% 40%	130935
	Night	17% 8% 2 5% 4 4 4 3 5% 6% 42%	129884
Transparency	Day	42% 6% 12% 22% 16% 3	134449
	Night	41% 5% 11% 22% 17% 3	134457
Seeing	Day	24% 16% 30% 19% 8% 2	16515
	Night	21% 15% 31% 24% 8% 1	25831

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	13% 7% 2 6% 5% 4 4 3 5% 5% 45%	4661
	11th to 20th	Day	14% 8% 3 7% 5% 4 4 3 4 5% 43%	4650
	21st to end	Day	16% 7% 3 6% 4 4 5% 4 6% 6% 40%	5702
February	1st to 10th	Day	15% 9% 2 7% 4 4 4 3 4 7% 39%	1890
	11th to 20th	Day	15% 7% 3 7% 5% 3 4 3 4 6% 41%	1971
	21st to end	Day	20% 9% 3 6% 4 4 4 3 4 5% 38%	1650
March	1st to 10th	Day	22% 7% 2 5% 4 3 4 3 4 5% 43%	4476
	11th to 20th	Day	12% 6% 3 6% 5% 4 4 4 6% 7% 43%	4878
	21st to end	Day	19% 7% 2 5% 4 3 3 3 5% 6% 43%	5868
April	1st to 10th	Day	19% 8% 2 7% 4 4 5% 3 4 6% 38%	2400
	11th to 20th	Day	18% 6% 2 6% 4 4 4 3 6% 7% 40%	2374
	21st to end	Day	18% 6% 3 6% 5% 4 4 3 5% 6% 40%	2400
May	1st to 10th	Day	29% 7% 2 5% 4 4 4 4 6% 7% 28%	5919
	11th to 20th	Day	25% 8% 3 6% 4 4 4 3 4 6% 34%	6318
	21st to end	Day	21% 6% 2 5% 4 4 5% 4 6% 8% 35%	6949
June	1st to 10th	Day	16% 6% 2 5% 5% 5% 4 5% 6% 9% 37%	2800
	11th to 20th	Day	17% 7% 2 6% 5% 5% 5% 5% 5% 7% 36%	2800
	21st to end	Day	14% 6% 2 6% 4 4 5% 4 6% 8% 40%	2800
July	1st to 10th	Day	11% 6% 2 7% 5% 5% 5% 4 6% 10% 37%	6360
	11th to 20th	Day	12% 7% 3 7% 5% 5% 6% 5% 7% 11% 33%	6360
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 4 6% 8% 39%	6926
August	1st to 10th	Day	21% 6% 2 6% 5% 5% 5% 4 5% 8% 33%	4262
	11th to 20th	Day	14% 5% 2 6% 4 4 5% 3 5% 8% 43%	3850
	21st to end	Day	12% 6% 2 5% 4 3 3 3 5% 8% 49%	4312
September	1st to 10th	Day	16% 5% 2 6% 4 4 4 3 5% 7% 44%	2400
	11th to 20th	Day	14% 5% 2 4 3 4 3 3 5% 8% 49%	2340
	21st to end	Day	19% 6% 2 8% 5% 4 4 3 5% 5% 39%	2200
October	1st to 10th	Day	19% 5% 2 5% 4 4 4 3 5% 7% 42%	2044
	11th to 20th	Day	16% 5% 2 5% 3 4 4 3 4 7% 46%	2000
	21st to end	Day	20% 6% 1 4 3 4 4 3 4 6% 45%	2076
November	1st to 10th	Day	13% 7% 2 5% 4 3 3 3 4 6% 52%	1851
	11th to 20th	Day	17% 6% 2 4 3 3 4 4 5% 6% 46%	1890
	21st to end	Day	16% 7% 2 4 4 4 4 4 5% 7% 43%	1764
December	1st to 10th	Day	16% 7% 2 5% 4 3 4 3 5% 7% 44%	2680
	11th to 20th	Day	22% 7% 2 4 3 3 4 3 5% 6% 42%	3066
	21st to end	Day	18% 8% 3 7% 4 5% 5% 4 6% 7% 35%	4048
January	1st to 10th	Night	13% 8% 3 6% 4 4 4 3 5% 6% 45%	8234
	11th to 20th	Night	15% 8% 3 6% 4 4 4 3 5% 6% 43%	8235
	21st to end	Night	16% 9% 2 5% 3 3 4 3 4 6% 45%	8464
February	1st to 10th	Night	16% 9% 3 6% 4 4 4 3 5% 6% 41%	2730
	11th to 20th	Night	16% 8% 3 6% 5% 4 4 3 5% 5% 41%	2425
	21st to end	Night	19% 8% 2 6% 4 4 4 2 4 6% 41%	1980
March	1st to 10th	Night	19% 9% 2 5% 3 3 3 3 5% 6% 43%	5364
	11th to 20th	Night	13% 7% 3 5% 4 3 3 3 4 5% 49%	5076
	21st to end	Night	17% 8% 3 6% 4 3 4 3 4 5% 42%	5064
April	1st to 10th	Night	18% 8% 2 5% 5% 5% 4 4 5% 6% 36%	2000
	11th to 20th	Night	18% 7% 2 5% 4 4 4 3 4 7% 40%	1975
	21st to end	Night	19% 7% 3 5% 3 3 4 3 6% 5% 44%	2000
May	1st to 10th	Night	27% 9% 3 6% 4 4 4 3 4 7% 28%	4050
	11th to 20th	Night	23% 10% 3 6% 4 4 4 3 5% 5% 34%	3575
	21st to end	Night	22% 6% 3 6% 3 4 4 3 5% 8% 36%	3926
June	1st to 10th	Night	17% 5% 3 5% 4 4 4 3 6% 7% 44%	1600
	11th to 20th	Night	15% 7% 2 6% 4 4 4 3 7% 8% 40%	1600
	21st to end	Night	12% 5% 2 5% 5% 4 5% 4 6% 9% 44%	1600
July	1st to 10th	Night	12% 7% 2 6% 5% 4 5% 4 6% 9% 40%	3600
	11th to 20th	Night	17% 8% 3 6% 5% 4 5% 4 7% 9% 33%	3600
	21st to end	Night	13% 6% 2 5% 3 4 4 4 6% 8% 44%	3926
August	1st to 10th	Night	23% 7% 2 6% 4 4 4 4 5% 9% 33%	2847
	11th to 20th	Night	15% 6% 2 7% 5% 5% 5% 4 5% 7% 40%	3188
	21st to end	Night	11% 5% 2 4 4 3 4 3 5% 7% 52%	3586
September	1st to 10th	Night	16% 6% 2 6% 4 4 4 3 5% 6% 44%	2000
	11th to 20th	Night	14% 5% 2 4 3 3 4 2 5% 7% 51%	2058
	21st to end	Night	19% 7% 2 6% 3 3 3 2 5% 6% 43%	2200
October	1st to 10th	Night	19% 7% 2 6% 3 3 3 3 4 5% 44%	2353
	11th to 20th	Night	17% 5% 2 4 3 4 4 3 4 5% 50%	2400
	21st to end	Night	20% 6% 2 5% 3 3 3 3 4 6% 46%	2762
November	1st to 10th	Night	12% 6% 2 5% 3 3 3 3 5% 6% 51%	2667
	11th to 20th	Night	18% 7% 2 5% 3 3 4 2 4 5% 48%	2730
	21st to end	Night	14% 7% 2 5% 4 3 4 4 5% 7% 44%	2851
December	1st to 10th	Night	13% 8% 3 5% 3 4 4 3 4 6% 46%	4720
	11th to 20th	Night	24% 7% 2 5% 3 3 3 2 4 5% 42%	5348
	21st to end	Night	21% 10% 3 6% 4 4 3 3 3 5% 40%	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	39% 5% 9% 28% 17% 2	4662
	11th to 20th	Day	44% 3 10% 20% 17% 6%	4680
	21st to end	Day	44% 5% 11% 23% 17% 1	5702
February	1st to 10th	Day	45% 5% 13% 22% 13% 2	1890
	11th to 20th	Day	44% 6% 9% 23% 15% 3	1980
	21st to end	Day	49% 4 10% 21% 13% 3	1650
March	1st to 10th	Day	43% 4 10% 22% 14% 8%	4479
	11th to 20th	Day	39% 6% 14% 26% 11% 5%	4878
	21st to end	Day	42% 4 11% 13% 25% 6%	5868
April	1st to 10th	Day	47% 5% 9% 19% 15% 5%	2400
	11th to 20th	Day	44% 4 12% 20% 17% 3	2374
	21st to end	Day	44% 5% 9% 20% 17% 5%	2400
May	1st to 10th	Day	54% 7% 13% 15% 10% 1	5930
	11th to 20th	Day	51% 6% 8% 20% 13% 2	6322
	21st to end	Day	44% 7% 11% 22% 14% 2	6949
June	1st to 10th	Day	43% 8% 13% 20% 15% 1	2800
	11th to 20th	Day	45% 8% 11% 22% 11% 2	2800
	21st to end	Day	40% 8% 13% 22% 16% 1	2800
July	1st to 10th	Day	42% 9% 12% 21% 14% 1	6290
	11th to 20th	Day	42% 9% 18% 20% 11% 1	6285
	21st to end	Day	41% 7% 11% 20% 21% 1	6728
August	1st to 10th	Day	48% 8% 13% 20% 10% 1	4248
	11th to 20th	Day	38% 6% 14% 28% 13% 1	3886
	21st to end	Day	34% 6% 10% 29% 19% 2	4312
September	1st to 10th	Day	39% 8% 10% 21% 19% 3	2400
	11th to 20th	Day	34% 5% 10% 23% 25% 3	2340
	21st to end	Day	47% 6% 9% 17% 18% 3	2200
October	1st to 10th	Day	38% 6% 9% 18% 25% 5%	3330
	11th to 20th	Day	28% 4 10% 25% 27% 5%	3240
	21st to end	Day	27% 3 15% 24% 27% 4	3327
November	1st to 10th	Day	34% 5% 12% 23% 22% 3	1851
	11th to 20th	Day	38% 5% 11% 22% 21% 4	1890
	21st to end	Day	41% 4 12% 28% 11% 2	1764
December	1st to 10th	Day	41% 4 15% 27% 12% 2	2680
	11th to 20th	Day	44% 5% 13% 24% 13% 2	3066
	21st to end	Day	46% 7% 10% 21% 15% 2	4048
January	1st to 10th	Night	40% 5% 12% 24% 17% 3	8234
	11th to 20th	Night	42% 4 12% 20% 16% 6%	8280
	21st to end	Night	41% 3 9% 21% 21% 4	8464
February	1st to 10th	Night	44% 6% 12% 24% 12% 3	2730
	11th to 20th	Night	44% 5% 11% 18% 17% 4	2427
	21st to end	Night	44% 4 8% 23% 17% 3	1980
March	1st to 10th	Night	43% 4 10% 22% 13% 9%	5374
	11th to 20th	Night	38% 5% 15% 23% 14% 4	5077
	21st to end	Night	44% 5% 7% 16% 22% 6%	5064
April	1st to 10th	Night	47% 6% 11% 19% 14% 4	2000
	11th to 20th	Night	44% 6% 9% 20% 19% 2	1975
	21st to end	Night	41% 6% 9% 22% 18% 4	2000
May	1st to 10th	Night	55% 6% 12% 15% 10% 1	4056
	11th to 20th	Night	50% 8% 12% 14% 14% 2	3576
	21st to end	Night	45% 7% 12% 23% 11% 2	3927
June	1st to 10th	Night	40% 5% 11% 22% 20% 1	1600
	11th to 20th	Night	41% 8% 13% 24% 12% 1	1600
	21st to end	Night	34% 10% 15% 24% 16% 1	1600
July	1st to 10th	Night	40% 9% 15% 19% 15% 2	3560
	11th to 20th	Night	46% 8% 14% 20% 11% 1	3552
	21st to end	Night	36% 7% 13% 23% 20% 1	3809
August	1st to 10th	Night	49% 8% 16% 17% 9% 1	2837
	11th to 20th	Night	42% 7% 13% 26% 11% 1	3218
	21st to end	Night	31% 6% 10% 31% 20% 1	3586
September	1st to 10th	Night	40% 7% 9% 23% 19% 1	2000
	11th to 20th	Night	34% 5% 10% 22% 25% 4	2058
	21st to end	Night	42% 5% 8% 23% 21% 2	2200
October	1st to 10th	Night	40% 5% 10% 23% 21% 2	3847
	11th to 20th	Night	27% 5% 9% 27% 28% 4	3899
	21st to end	Night	29% 4 12% 32% 20% 3	4461
November	1st to 10th	Night	33% 6% 12% 24% 22% 4	2667
	11th to 20th	Night	40% 5% 8% 23% 20% 4	2730
	21st to end	Night	39% 5% 13% 26% 15% 1	2851
December	1st to 10th	Night	39% 5% 12% 31% 12% 2	4720
	11th to 20th	Night	45% 4 10% 22% 15% 3	5348
	21st to end	Night	49% 4 10% 18% 16% 3	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	29% 26% 33% 10% 1	220
	11th to 20th	Day	39% 24% 29% 8%	220
	21st to end	Day	28% 30% 29% 7% 4	349
February	1st to 10th	Day	29% 30% 32% 7% 2	330
	11th to 20th	Day	32% 25% 33% 9%	489
	21st to end	Day	33% 24% 27% 13% 2	414
March	1st to 10th	Day	31% 24% 29% 13% 3	500
	11th to 20th	Day	27% 26% 31% 13% 2 1	500
	21st to end	Day	32% 22% 30% 11% 4 1	550
April	1st to 10th	Day	33% 22% 29% 9% 6%	500
	11th to 20th	Day	27% 24% 29% 12% 7% 1	492
	21st to end	Day	30% 19% 35% 13% 3 1	500
May	1st to 10th	Day	33% 19% 29% 13% 6% 1	503
	11th to 20th	Day	25% 16% 35% 17% 7% 1	527
	21st to end	Day	24% 10% 28% 26% 10% 1	573
June	1st to 10th	Day	19% 15% 31% 22% 11% 1	530
	11th to 20th	Day	22% 14% 31% 23% 10% 1	530
	21st to end	Day	18% 10% 32% 28% 10% 1	530
July	1st to 10th	Day	13% 8% 30% 29% 16% 4	525
	11th to 20th	Day	11% 5% 28% 36% 16% 3	524
	21st to end	Day	16% 9% 32% 28% 12% 3	576
August	1st to 10th	Day	15% 7% 27% 30% 16% 5%	526
	11th to 20th	Day	15% 6% 27% 33% 14% 5%	519
	21st to end	Day	14% 9% 32% 27% 13% 6%	583
September	1st to 10th	Day	18% 12% 25% 25% 15% 4	530
	11th to 20th	Day	16% 8% 29% 24% 14% 9%	530
	21st to end	Day	24% 14% 28% 22% 8% 5%	530
October	1st to 10th	Day	24% 8% 30% 20% 13% 5%	530
	11th to 20th	Day	20% 18% 30% 21% 9% 2	530
	21st to end	Day	25% 16% 33% 18% 7% 1	514
November	1st to 10th	Day	22% 16% 30% 21% 9% 2	425
	11th to 20th	Day	27% 20% 32% 17% 4	430
	21st to end	Day	26% 22% 34% 14% 3	304
December	1st to 10th	Day	30% 26% 27% 11% 5%	220
	11th to 20th	Day	36% 25% 25% 10% 3	220
	21st to end	Day	31% 19% 33% 12% 5%	242
January	1st to 10th	Night	23% 23% 35% 16% 3	840
	11th to 20th	Night	28% 19% 33% 18% 3	840
	21st to end	Night	23% 22% 37% 17% 2	924
February	1st to 10th	Night	25% 19% 37% 18% 2	840
	11th to 20th	Night	25% 26% 36% 12% 1	804
	21st to end	Night	27% 19% 37% 15% 2	660
March	1st to 10th	Night	25% 23% 31% 18% 3	800
	11th to 20th	Night	24% 22% 33% 18% 3 1	800
	21st to end	Night	23% 20% 38% 14% 5%	880
April	1st to 10th	Night	24% 22% 34% 17% 4	800
	11th to 20th	Night	23% 18% 36% 19% 4	791
	21st to end	Night	23% 15% 35% 23% 4	800
May	1st to 10th	Night	27% 16% 31% 20% 5%	609
	11th to 20th	Night	23% 13% 35% 23% 7%	394
	21st to end	Night	19% 7% 28% 35% 11%	433
June	1st to 10th	Night	19% 7% 29% 35% 10% 1	400
	11th to 20th	Night	15% 8% 31% 35% 12%	400
	21st to end	Night	13% 5% 28% 43% 11%	400
July	1st to 10th	Night	13% 7% 25% 35% 18% 2	390
	11th to 20th	Night	13% 5% 24% 39% 18% 1	388
	21st to end	Night	15% 3 26% 41% 14% 1	438
August	1st to 10th	Night	14% 2 23% 40% 20% 2	555
	11th to 20th	Night	14% 3 23% 37% 22% 2	781
	21st to end	Night	16% 4 24% 36% 19% 1	880
September	1st to 10th	Night	19% 5% 27% 33% 16% 2	800
	11th to 20th	Night	17% 4 25% 32% 19% 3	800
	21st to end	Night	21% 7% 27% 31% 13% 2	800
October	1st to 10th	Night	22% 10% 27% 25% 15% 2	800
	11th to 20th	Night	19% 14% 29% 27% 10%	800
	21st to end	Night	23% 15% 32% 23% 7%	880
November	1st to 10th	Night	18% 13% 32% 26% 9% 1	820
	11th to 20th	Night	25% 17% 30% 22% 6%	840
	21st to end	Night	20% 20% 33% 21% 5% 1	840
December	1st to 10th	Night	25% 19% 32% 20% 4 1	840
	11th to 20th	Night	24% 19% 34% 19% 3	840
	21st to end	Night	26% 18% 34% 20% 2	924

Page generated at 2026-02-13 01:42:16. Version ac07

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