Dogwood Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dogwood Ridge Observatory clear sky chart from 2005-11-06 to 2026-01-17.

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	13% 5% 2 6% 4 4 5% 4 6% 8% 43%	126930
	Night	14% 6% 2 6% 4 4 4 4 5% 7% 44%	124734
Transparency	Day	39% 4 12% 23% 18% 5%	130536
	Night	39% 4 10% 23% 19% 5%	129197
Seeing	Day	19% 10% 26% 25% 15% 6%	16575
	Night	17% 8% 27% 32% 14% 2	26420

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	16% 5% 2 4 3 4 4 3 5% 5% 51%	4146
	11th to 20th	Day	14% 7% 2 5% 3 3 3 3 4 4 53%	4114
	21st to end	Day	15% 7% 2 6% 4 3 4 4 4 6% 45%	4466
February	1st to 10th	Day	13% 8% 3 6% 4 4 5% 5% 6% 6% 41%	1800
	11th to 20th	Day	20% 6% 2 6% 4 3 3 3 5% 5% 42%	1758
	21st to end	Day	17% 8% 2 7% 4 4 5% 3 4 6% 39%	1720
March	1st to 10th	Day	17% 6% 2 5% 4 4 5% 4 6% 7% 40%	4935
	11th to 20th	Day	11% 5% 2 5% 3 3 4 3 5% 7% 51%	4980
	21st to end	Day	16% 6% 3 6% 5% 4 4 4 5% 6% 40%	5465
April	1st to 10th	Day	12% 6% 2 5% 4 4 4 4 5% 6% 49%	2368
	11th to 20th	Day	12% 6% 2 5% 4 3 4 4 5% 6% 48%	2374
	21st to end	Day	16% 5% 2 5% 5% 5% 4 4 5% 6% 43%	2408
May	1st to 10th	Day	13% 7% 3 7% 5% 5% 6% 5% 7% 9% 33%	5862
	11th to 20th	Day	20% 7% 3 7% 4 5% 5% 4 6% 9% 31%	5861
	21st to end	Day	15% 4 2 5% 4 4 4 3 6% 9% 42%	6748
June	1st to 10th	Day	9% 4 2 5% 5% 5% 5% 5% 7% 10% 44%	2800
	11th to 20th	Day	11% 4 2 6% 4 5% 5% 5% 8% 10% 40%	2800
	21st to end	Day	7% 4 2 5% 4 5% 6% 5% 8% 11% 44%	2800
July	1st to 10th	Day	7% 4 2 6% 5% 5% 5% 5% 8% 11% 43%	6041
	11th to 20th	Day	9% 6% 2 7% 6% 6% 7% 6% 9% 13% 30%	5900
	21st to end	Day	9% 5% 2 6% 6% 5% 6% 5% 7% 11% 38%	6424
August	1st to 10th	Day	16% 6% 2 7% 4 5% 6% 5% 8% 10% 32%	4234
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 5% 8% 10% 40%	4060
	21st to end	Day	8% 4 1 5% 4 4 4 4 5% 11% 50%	4312
September	1st to 10th	Day	11% 5% 2 6% 4 4 4 4 5% 7% 48%	2400
	11th to 20th	Day	13% 5% 2 5% 4 4 4 3 6% 8% 45%	2329
	21st to end	Day	22% 6% 3 6% 4 4 4 4 6% 6% 36%	2125
October	1st to 10th	Day	14% 5% 2 5% 4 3 4 3 4 5% 51%	2000
	11th to 20th	Day	15% 4 1 4 4 3 4 3 5% 5% 52%	2000
	21st to end	Day	14% 5% 2 5% 2 3 2 2 5% 4 55%	2200
November	1st to 10th	Day	12% 4 2 4 4 3 4 3 5% 6% 54%	2057
	11th to 20th	Day	14% 5% 2 5% 3 3 3 3 5% 5% 51%	1889
	21st to end	Day	15% 5% 1 5% 3 3 4 3 5% 5% 51%	1680
December	1st to 10th	Day	12% 6% 3 4 4 3 3 4 5% 6% 50%	2680
	11th to 20th	Day	20% 6% 2 5% 2 3 3 3 5% 6% 46%	3070
	21st to end	Day	18% 6% 3 7% 4 3 4 3 5% 6% 40%	4124
January	1st to 10th	Night	12% 6% 2 4 3 4 3 3 4 5% 54%	6019
	11th to 20th	Night	14% 6% 2 4 3 3 2 2 3 4 56%	5979
	21st to end	Night	15% 6% 2 5% 3 3 3 2 4 4 50%	6490
February	1st to 10th	Night	14% 7% 2 5% 4 4 4 3 6% 7% 43%	2600
	11th to 20th	Night	20% 8% 2 4 4 4 4 2 4 5% 43%	2527
	21st to end	Night	16% 7% 2 5% 3 3 4 3 5% 6% 46%	1905
March	1st to 10th	Night	15% 6% 2 6% 4 3 4 3 5% 6% 47%	4918
	11th to 20th	Night	10% 4 1 5% 3 3 3 3 5% 8% 54%	4980
	21st to end	Night	13% 6% 2 6% 4 4 4 4 5% 7% 46%	5467
April	1st to 10th	Night	15% 6% 2 5% 5% 3 4 3 5% 7% 45%	2031
	11th to 20th	Night	11% 6% 2 5% 3 3 3 3 5% 9% 48%	1975
	21st to end	Night	14% 6% 2 4 4 4 4 4 5% 7% 45%	2000
May	1st to 10th	Night	16% 8% 3 7% 5% 5% 4 3 5% 9% 34%	4042
	11th to 20th	Night	22% 7% 2 6% 4 4 4 4 6% 9% 31%	4032
	21st to end	Night	15% 6% 2 6% 4 4 5% 4 6% 8% 39%	4102
June	1st to 10th	Night	10% 5% 1 6% 4 4 5% 5% 7% 8% 43%	1600
	11th to 20th	Night	10% 6% 2 6% 5% 5% 5% 4 7% 9% 42%	1600
	21st to end	Night	8% 4 2 5% 5% 5% 4 4 7% 10% 45%	1600
July	1st to 10th	Night	10% 6% 2 7% 5% 5% 6% 5% 7% 10% 36%	3910
	11th to 20th	Night	12% 8% 4 9% 6% 6% 6% 6% 8% 10% 26%	4057
	21st to end	Night	8% 7% 3 9% 6% 6% 7% 6% 7% 9% 32%	4427
August	1st to 10th	Night	16% 6% 3 7% 6% 4 5% 4 8% 9% 32%	2915
	11th to 20th	Night	10% 6% 3 8% 5% 5% 6% 6% 7% 9% 35%	2941
	21st to end	Night	10% 6% 2 6% 5% 5% 5% 4 6% 9% 43%	3586
September	1st to 10th	Night	12% 5% 2 5% 4 5% 4 3 5% 7% 47%	2000
	11th to 20th	Night	13% 5% 2 5% 4 4 6% 4 5% 8% 44%	2068
	21st to end	Night	24% 8% 3 5% 3 3 3 4 5% 5% 37%	2275
October	1st to 10th	Night	17% 5% 2 6% 2 4 3 3 4 6% 47%	2400
	11th to 20th	Night	15% 4 2 6% 3 3 3 3 5% 6% 49%	2400
	21st to end	Night	13% 4 2 4 3 3 4 3 4 6% 54%	2640
November	1st to 10th	Night	13% 6% 2 6% 4 3 3 2 3 5% 53%	2461
	11th to 20th	Night	13% 5% 2 5% 4 4 3 3 4 6% 50%	2726
	21st to end	Night	12% 4 2 5% 3 4 4 4 5% 5% 51%	2940
December	1st to 10th	Night	10% 5% 2 4 3 3 4 3 5% 6% 54%	4720
	11th to 20th	Night	20% 7% 2 6% 3 4 4 3 4 5% 42%	5345
	21st to end	Night	17% 6% 2 5% 3 4 4 3 5% 7% 44%	7056

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	37% 2 5% 24% 22% 10%	4147
	11th to 20th	Day	37% 2 5% 19% 24% 13%	4114
	21st to end	Day	42% 2 6% 27% 19% 4	4466
February	1st to 10th	Day	43% 4 9% 26% 15% 3	1800
	11th to 20th	Day	44% 3 6% 22% 20% 5%	1767
	21st to end	Day	46% 3 10% 17% 18% 6%	1720
March	1st to 10th	Day	44% 2 9% 19% 16% 10%	4935
	11th to 20th	Day	34% 3 7% 25% 22% 9%	4980
	21st to end	Day	45% 3 10% 18% 18% 7%	5465
April	1st to 10th	Day	36% 3 10% 23% 19% 9%	2368
	11th to 20th	Day	36% 3 10% 22% 22% 6%	2374
	21st to end	Day	42% 4 10% 24% 16% 4	2408
May	1st to 10th	Day	45% 6% 15% 20% 13% 1	5897
	11th to 20th	Day	50% 5% 11% 20% 13% 1	5865
	21st to end	Day	39% 4 14% 20% 20% 2	6763
June	1st to 10th	Day	34% 6% 16% 26% 17% 1	2800
	11th to 20th	Day	37% 7% 16% 23% 16% 2	2800
	21st to end	Day	32% 7% 16% 28% 16% 2	2800
July	1st to 10th	Day	33% 8% 21% 19% 13% 4	5976
	11th to 20th	Day	42% 10% 20% 21% 6% 1	5831
	21st to end	Day	38% 7% 14% 25% 16%	6240
August	1st to 10th	Day	45% 6% 16% 25% 7% 1	4221
	11th to 20th	Day	37% 6% 16% 26% 14% 1	4099
	21st to end	Day	30% 5% 18% 29% 18% 1	4312
September	1st to 10th	Day	37% 4 14% 19% 22% 5%	2400
	11th to 20th	Day	37% 5% 7% 27% 20% 4	2329
	21st to end	Day	48% 4 8% 19% 17% 3	2125
October	1st to 10th	Day	34% 3 6% 19% 31% 5%	3260
	11th to 20th	Day	26% 3 6% 23% 31% 12%	3240
	21st to end	Day	22% 2 9% 30% 25% 12%	3538
November	1st to 10th	Day	32% 3 8% 24% 28% 5%	2057
	11th to 20th	Day	35% 3 9% 24% 22% 8%	1889
	21st to end	Day	35% 3 9% 25% 24% 4	1680
December	1st to 10th	Day	36% 3 10% 25% 18% 8%	2680
	11th to 20th	Day	40% 2 12% 24% 16% 5%	3066
	21st to end	Day	46% 2 10% 24% 16% 1	4124
January	1st to 10th	Night	34% 2 5% 21% 27% 11%	6019
	11th to 20th	Night	35% 2 4 21% 27% 11%	5979
	21st to end	Night	39% 2 6% 26% 21% 6%	6490
February	1st to 10th	Night	41% 4 10% 25% 18% 3	2600
	11th to 20th	Night	45% 2 7% 20% 20% 7%	2529
	21st to end	Night	41% 2 9% 22% 18% 8%	1905
March	1st to 10th	Night	39% 2 6% 23% 20% 9%	4918
	11th to 20th	Night	30% 3 7% 22% 29% 10%	4980
	21st to end	Night	39% 3 9% 21% 22% 6%	5467
April	1st to 10th	Night	39% 4 9% 18% 22% 7%	2031
	11th to 20th	Night	34% 3 13% 21% 23% 6%	1975
	21st to end	Night	37% 4 11% 24% 18% 6%	2000
May	1st to 10th	Night	48% 5% 15% 19% 11% 2	4069
	11th to 20th	Night	50% 4 10% 24% 10% 2	4033
	21st to end	Night	44% 4 14% 24% 12% 2	4109
June	1st to 10th	Night	35% 6% 13% 27% 18% 1	1600
	11th to 20th	Night	38% 6% 17% 22% 15% 2	1600
	21st to end	Night	34% 6% 14% 25% 18% 3	1600
July	1st to 10th	Night	41% 9% 19% 15% 13% 2	3867
	11th to 20th	Night	51% 11% 16% 16% 5% 1	4006
	21st to end	Night	45% 8% 13% 21% 13%	4297
August	1st to 10th	Night	48% 6% 16% 23% 6% 1	2904
	11th to 20th	Night	42% 7% 15% 24% 11% 1	2968
	21st to end	Night	38% 5% 14% 30% 12% 2	3586
September	1st to 10th	Night	37% 5% 12% 22% 17% 7%	2000
	11th to 20th	Night	38% 5% 10% 25% 20% 3	2068
	21st to end	Night	48% 5% 9% 20% 15% 3	2275
October	1st to 10th	Night	41% 4 8% 19% 22% 6%	3920
	11th to 20th	Night	27% 3 7% 21% 31% 11%	3899
	21st to end	Night	22% 2 6% 31% 28% 11%	4252
November	1st to 10th	Night	36% 3 7% 21% 27% 6%	2461
	11th to 20th	Night	37% 3 7% 21% 24% 8%	2726
	21st to end	Night	35% 3 9% 24% 23% 6%	2940
December	1st to 10th	Night	32% 2 9% 28% 24% 5%	4720
	11th to 20th	Night	45% 3 10% 19% 16% 7%	5348
	21st to end	Night	42% 3 10% 27% 17% 2	7056

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	25% 22% 31% 19% 4	330
	11th to 20th	Day	28% 27% 31% 11% 2	318
	21st to end	Day	26% 22% 37% 12% 3	330
February	1st to 10th	Day	25% 20% 39% 12% 3	300
	11th to 20th	Day	40% 22% 27% 10% 1	305
	21st to end	Day	29% 15% 31% 21% 4	414
March	1st to 10th	Day	24% 17% 31% 21% 6%	500
	11th to 20th	Day	23% 18% 35% 17% 7% 1	500
	21st to end	Day	24% 15% 37% 19% 5% 1	550
April	1st to 10th	Day	24% 17% 31% 18% 8% 1	500
	11th to 20th	Day	19% 15% 32% 20% 10% 5%	492
	21st to end	Day	24% 11% 32% 23% 9% 3	500
May	1st to 10th	Day	20% 14% 30% 23% 10% 3	503
	11th to 20th	Day	21% 9% 28% 26% 12% 4	527
	21st to end	Day	19% 6% 23% 29% 19% 5%	573
June	1st to 10th	Day	11% 7% 27% 28% 22% 5%	530
	11th to 20th	Day	13% 6% 22% 30% 18% 10%	530
	21st to end	Day	10% 4 22% 34% 23% 8%	530
July	1st to 10th	Day	11% 2 17% 31% 28% 10%	525
	11th to 20th	Day	7% 2 13% 35% 31% 12%	524
	21st to end	Day	11% 4 17% 31% 23% 14%	576
August	1st to 10th	Day	15% 3 17% 27% 26% 11%	526
	11th to 20th	Day	12% 3 17% 29% 26% 13%	519
	21st to end	Day	10% 2 17% 31% 25% 14%	583
September	1st to 10th	Day	14% 4 17% 29% 20% 16%	530
	11th to 20th	Day	16% 3 13% 34% 23% 11%	530
	21st to end	Day	30% 5% 21% 27% 13% 4	530
October	1st to 10th	Day	19% 5% 22% 29% 18% 8%	530
	11th to 20th	Day	16% 11% 24% 27% 18% 3	530
	21st to end	Day	18% 11% 31% 26% 11% 3	583
November	1st to 10th	Day	15% 11% 27% 31% 12% 4	535
	11th to 20th	Day	19% 13% 32% 23% 10% 2	401
	21st to end	Day	22% 20% 26% 22% 9% 1	220
December	1st to 10th	Day	25% 12% 39% 16% 6% 1	220
	11th to 20th	Day	26% 13% 30% 23% 7% 2	220
	21st to end	Day	29% 16% 28% 17% 8% 2	261
January	1st to 10th	Night	19% 13% 39% 26% 3	840
	11th to 20th	Night	20% 15% 36% 26% 3	825
	21st to end	Night	18% 13% 41% 26% 3	880
February	1st to 10th	Night	18% 12% 37% 31% 3	800
	11th to 20th	Night	26% 14% 38% 21% 1	783
	21st to end	Night	22% 14% 37% 24% 3	660
March	1st to 10th	Night	18% 16% 36% 25% 5%	800
	11th to 20th	Night	21% 15% 34% 24% 5% 1	800
	21st to end	Night	20% 12% 36% 26% 5%	880
April	1st to 10th	Night	18% 15% 37% 25% 6%	800
	11th to 20th	Night	14% 13% 34% 30% 9%	791
	21st to end	Night	17% 8% 31% 35% 9%	800
May	1st to 10th	Night	19% 9% 30% 30% 12%	609
	11th to 20th	Night	21% 4 21% 37% 16% 1	591
	21st to end	Night	17% 2 18% 38% 22% 3	512
June	1st to 10th	Night	10% 3 18% 45% 24% 1	400
	11th to 20th	Night	12% 4 17% 40% 26% 1	400
	21st to end	Night	9% 2 17% 49% 21% 2	400
July	1st to 10th	Night	11% 3 12% 38% 32% 4	515
	11th to 20th	Night	8% 1 11% 40% 35% 6%	582
	21st to end	Night	8% 2 13% 42% 29% 5%	657
August	1st to 10th	Night	15% 2 9% 39% 31% 4	597
	11th to 20th	Night	14% 3 9% 37% 34% 4	634
	21st to end	Night	11% 2 12% 38% 32% 4	880
September	1st to 10th	Night	15% 2 11% 35% 31% 6%	800
	11th to 20th	Night	14% 3 13% 34% 31% 4	800
	21st to end	Night	27% 4 16% 32% 20% 2	800
October	1st to 10th	Night	20% 4 17% 31% 24% 5%	800
	11th to 20th	Night	17% 8% 24% 35% 16% 1	800
	21st to end	Night	16% 7% 29% 34% 13% 1	880
November	1st to 10th	Night	16% 8% 26% 37% 13% 1	820
	11th to 20th	Night	18% 10% 32% 31% 10%	840
	21st to end	Night	14% 10% 34% 33% 10%	840
December	1st to 10th	Night	20% 9% 35% 28% 7%	840
	11th to 20th	Night	18% 9% 32% 35% 5%	840
	21st to end	Night	21% 10% 31% 35% 3	924

Page generated at 2026-01-14 01:14:27. Version ac07

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