Dad's Nest
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dad's Nest clear sky chart from 2005-11-06 to 2026-08-15.

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	16% 8% 3 8% 5% 5% 5% 4 6% 7% 33%	144079
	Night	17% 9% 3 8% 5% 5% 5% 4 6% 7% 33%	137826
Transparency	Day	48% 7% 12% 21% 11% 1	147557
	Night	50% 7% 11% 19% 11% 1	142437
Seeing	Day	23% 17% 29% 20% 9% 3	17002
	Night	22% 15% 29% 25% 8% 1	26003

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	10% 11% 5% 17% 8% 6% 7% 5% 5% 5% 20%	4661
	11th to 20th	Day	11% 14% 7% 13% 7% 7% 6% 5% 5% 6% 20%	4650
	21st to end	Day	13% 11% 3 10% 7% 6% 5% 4 5% 6% 29%	5346
February	1st to 10th	Day	12% 12% 4 11% 8% 7% 6% 3 6% 6% 25%	1890
	11th to 20th	Day	12% 11% 5% 13% 8% 6% 5% 4 5% 6% 25%	1981
	21st to end	Day	17% 13% 4 11% 5% 4 5% 4 5% 5% 27%	1730
March	1st to 10th	Day	19% 12% 4 9% 5% 4 5% 3 4 5% 29%	4576
	11th to 20th	Day	14% 10% 3 8% 6% 5% 5% 4 5% 6% 34%	4893
	21st to end	Day	19% 11% 3 8% 5% 4 4 3 4 5% 34%	6047
April	1st to 10th	Day	19% 10% 3 8% 5% 4 5% 4 4 6% 33%	2520
	11th to 20th	Day	17% 8% 3 7% 5% 5% 5% 4 5% 6% 35%	2494
	21st to end	Day	19% 8% 4 8% 5% 5% 4 3 5% 5% 33%	2599
May	1st to 10th	Day	29% 7% 3 7% 4 4 5% 4 6% 6% 26%	7933
	11th to 20th	Day	17% 8% 3 7% 5% 5% 5% 4 6% 7% 33%	8221
	21st to end	Day	21% 7% 3 6% 5% 5% 5% 4 6% 8% 30%	9060
June	1st to 10th	Day	16% 7% 2 7% 6% 5% 5% 4 6% 9% 33%	2940
	11th to 20th	Day	17% 5% 2 6% 5% 5% 5% 5% 7% 9% 34%	2940
	21st to end	Day	16% 6% 3 7% 5% 5% 5% 4 7% 9% 34%	2940
July	1st to 10th	Day	12% 5% 2 6% 5% 4 5% 4 7% 10% 38%	8280
	11th to 20th	Day	9% 4 2 5% 4 5% 5% 5% 7% 11% 43%	8280
	21st to end	Day	16% 5% 2 5% 4 5% 5% 4 6% 7% 42%	8993
August	1st to 10th	Day	16% 4 2 6% 5% 5% 5% 4 6% 8% 37%	4652
	11th to 20th	Day	15% 6% 2 6% 5% 5% 6% 5% 7% 9% 33%	3945
	21st to end	Day	14% 5% 2 5% 5% 5% 6% 4 7% 8% 40%	4312
September	1st to 10th	Day	13% 5% 2 5% 4 5% 5% 4 5% 7% 44%	2400
	11th to 20th	Day	13% 4 2 5% 3 4 4 4 6% 7% 47%	2330
	21st to end	Day	18% 6% 2 5% 5% 4 4 4 6% 7% 39%	2200
October	1st to 10th	Day	21% 6% 2 8% 5% 4 5% 3 4 7% 34%	2051
	11th to 20th	Day	15% 8% 2 7% 5% 5% 5% 4 6% 7% 37%	2000
	21st to end	Day	23% 9% 3 6% 4 4 4 4 6% 6% 30%	2005
November	1st to 10th	Day	14% 9% 3 6% 4 4 4 3 6% 8% 38%	1851
	11th to 20th	Day	15% 9% 2 7% 4 5% 6% 4 6% 7% 34%	1885
	21st to end	Day	18% 12% 4 8% 5% 5% 5% 4 6% 6% 29%	1680
December	1st to 10th	Day	17% 16% 6% 12% 5% 5% 4 3 6% 5% 20%	2680
	11th to 20th	Day	21% 11% 5% 8% 5% 4 4 4 5% 6% 27%	3066
	21st to end	Day	20% 13% 6% 11% 5% 4 4 3 4 6% 23%	4048
January	1st to 10th	Night	12% 12% 4 13% 8% 6% 5% 4 5% 6% 23%	8234
	11th to 20th	Night	11% 14% 6% 14% 8% 7% 6% 4 6% 6% 18%	8235
	21st to end	Night	12% 11% 4 9% 5% 5% 6% 4 7% 8% 29%	8821
February	1st to 10th	Night	12% 12% 4 9% 8% 6% 6% 4 6% 6% 27%	2730
	11th to 20th	Night	12% 10% 4 11% 7% 6% 5% 4 7% 7% 29%	2523
	21st to end	Night	15% 10% 4 11% 6% 4 4 4 6% 7% 29%	2076
March	1st to 10th	Night	20% 10% 4 9% 5% 5% 4 4 6% 6% 28%	5484
	11th to 20th	Night	16% 10% 3 7% 5% 4 4 3 5% 7% 35%	5282
	21st to end	Night	19% 10% 4 10% 4 4 4 3 5% 5% 31%	5126
April	1st to 10th	Night	21% 8% 3 8% 5% 4 4 3 5% 7% 33%	2100
	11th to 20th	Night	18% 9% 2 6% 5% 4 4 4 5% 6% 36%	2075
	21st to end	Night	20% 7% 3 6% 5% 4 4 3 5% 5% 38%	2021
May	1st to 10th	Night	29% 7% 3 7% 5% 4 4 4 5% 6% 27%	5020
	11th to 20th	Night	18% 8% 3 8% 5% 4 4 3 6% 7% 34%	4639
	21st to end	Night	20% 7% 3 7% 5% 5% 5% 4 5% 7% 32%	5114
June	1st to 10th	Night	16% 6% 2 5% 5% 4 4 3 5% 8% 40%	1680
	11th to 20th	Night	17% 7% 3 5% 4 4 5% 4 5% 8% 40%	1680
	21st to end	Night	16% 5% 2 5% 4 4 5% 4 5% 8% 42%	1680
July	1st to 10th	Night	13% 5% 3 6% 5% 5% 5% 4 7% 8% 40%	4680
	11th to 20th	Night	12% 5% 2 6% 4 4 5% 4 5% 8% 43%	4680
	21st to end	Night	13% 5% 2 5% 3 4 5% 3 5% 7% 48%	5084
August	1st to 10th	Night	20% 6% 2 6% 4 4 5% 4 5% 7% 37%	2713
	11th to 20th	Night	18% 6% 2 5% 4 4 4 3 5% 7% 41%	3159
	21st to end	Night	14% 4 1 5% 3 3 3 4 6% 9% 47%	3586
September	1st to 10th	Night	13% 4 2 5% 4 4 5% 4 6% 7% 47%	2000
	11th to 20th	Night	13% 5% 2 6% 3 3 3 3 5% 6% 52%	2070
	21st to end	Night	17% 5% 2 5% 4 4 4 4 5% 7% 44%	2200
October	1st to 10th	Night	20% 6% 3 6% 4 4 5% 3 5% 6% 37%	2345
	11th to 20th	Night	17% 6% 2 7% 4 5% 4 4 6% 6% 39%	2400
	21st to end	Night	20% 9% 2 7% 5% 4 4 3 6% 7% 32%	2833
November	1st to 10th	Night	14% 8% 2 7% 5% 4 4 4 6% 6% 40%	2667
	11th to 20th	Night	18% 8% 3 7% 5% 4 5% 4 5% 6% 35%	2731
	21st to end	Night	16% 10% 3 8% 5% 5% 4 4 6% 7% 33%	2940
December	1st to 10th	Night	15% 14% 5% 8% 5% 5% 5% 4 7% 8% 25%	4720
	11th to 20th	Night	24% 11% 4 8% 5% 4 4 4 5% 5% 27%	5348
	21st to end	Night	23% 14% 5% 9% 5% 4 3 3 4 5% 26%	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	60% 9% 9% 16% 5% 1	4662
	11th to 20th	Day	63% 8% 7% 9% 11% 2	4680
	21st to end	Day	53% 7% 9% 20% 10% 1	5346
February	1st to 10th	Day	58% 7% 11% 16% 7% 1	1890
	11th to 20th	Day	59% 8% 9% 15% 8% 2	1990
	21st to end	Day	57% 7% 10% 16% 9% 1	1730
March	1st to 10th	Day	58% 6% 8% 13% 10% 4	4579
	11th to 20th	Day	49% 7% 19% 14% 8% 3	4893
	21st to end	Day	52% 5% 7% 16% 18% 3	6047
April	1st to 10th	Day	53% 6% 9% 18% 12% 2	2520
	11th to 20th	Day	49% 7% 10% 19% 13% 2	2494
	21st to end	Day	52% 6% 9% 18% 12% 3	2599
May	1st to 10th	Day	58% 6% 9% 17% 9% 1	7945
	11th to 20th	Day	49% 8% 12% 21% 10% 1	8225
	21st to end	Day	51% 7% 11% 23% 8%	9061
June	1st to 10th	Day	46% 9% 13% 20% 11% 1	2940
	11th to 20th	Day	44% 8% 15% 20% 11% 1	2940
	21st to end	Day	44% 9% 14% 22% 10% 1	2940
July	1st to 10th	Day	41% 6% 17% 25% 11%	8210
	11th to 20th	Day	34% 7% 15% 32% 12% 1	8205
	21st to end	Day	41% 5% 13% 29% 11%	8795
August	1st to 10th	Day	44% 7% 16% 20% 12% 1	4638
	11th to 20th	Day	44% 9% 16% 25% 6%	3982
	21st to end	Day	39% 7% 14% 31% 9% 1	4312
September	1st to 10th	Day	37% 8% 14% 29% 11% 1	2400
	11th to 20th	Day	34% 8% 12% 28% 18% 1	2330
	21st to end	Day	43% 6% 12% 26% 13% 1	2200
October	1st to 10th	Day	45% 7% 9% 24% 14% 1	3337
	11th to 20th	Day	40% 6% 13% 25% 15% 2	3240
	21st to end	Day	38% 7% 14% 27% 13% 1	3217
November	1st to 10th	Day	42% 8% 15% 22% 13% 1	1851
	11th to 20th	Day	48% 7% 11% 18% 14% 1	1885
	21st to end	Day	54% 8% 15% 15% 6% 1	1680
December	1st to 10th	Day	65% 6% 11% 14% 4	2680
	11th to 20th	Day	56% 7% 11% 17% 8%	3066
	21st to end	Day	63% 6% 7% 14% 10% 1	4048
January	1st to 10th	Night	60% 7% 10% 13% 9%	8234
	11th to 20th	Night	63% 9% 9% 9% 9% 2	8280
	21st to end	Night	51% 7% 9% 16% 16% 2	8821
February	1st to 10th	Night	55% 8% 11% 19% 8% 1	2730
	11th to 20th	Night	53% 7% 12% 17% 10% 1	2525
	21st to end	Night	53% 7% 13% 17% 8% 1	2076
March	1st to 10th	Night	56% 7% 10% 13% 12% 2	5494
	11th to 20th	Night	47% 8% 17% 18% 8% 2	5283
	21st to end	Night	55% 5% 6% 17% 15% 2	5126
April	1st to 10th	Night	52% 5% 11% 19% 12% 1	2100
	11th to 20th	Night	48% 8% 11% 20% 13% 1	2075
	21st to end	Night	47% 6% 10% 18% 16% 3	2021
May	1st to 10th	Night	59% 6% 10% 13% 11% 1	5026
	11th to 20th	Night	50% 6% 13% 21% 9% 1	4640
	21st to end	Night	51% 7% 12% 20% 10% 1	5115
June	1st to 10th	Night	42% 6% 12% 24% 13% 2	1680
	11th to 20th	Night	41% 7% 15% 23% 13% 1	1680
	21st to end	Night	39% 9% 14% 26% 12%	1680
July	1st to 10th	Night	42% 5% 17% 22% 13% 1	4640
	11th to 20th	Night	40% 6% 11% 24% 18% 1	4632
	21st to end	Night	37% 6% 13% 30% 13% 1	4967
August	1st to 10th	Night	46% 9% 13% 22% 9%	2703
	11th to 20th	Night	43% 7% 15% 25% 9%	3188
	21st to end	Night	34% 7% 13% 36% 10%	3586
September	1st to 10th	Night	36% 8% 12% 30% 13% 1	2000
	11th to 20th	Night	34% 6% 12% 28% 20% 1	2070
	21st to end	Night	39% 7% 12% 25% 15% 2	2200
October	1st to 10th	Night	49% 7% 9% 21% 13% 1	3839
	11th to 20th	Night	37% 6% 13% 24% 18% 2	3899
	21st to end	Night	42% 6% 13% 29% 10% 1	4571
November	1st to 10th	Night	44% 7% 12% 22% 13% 2	2667
	11th to 20th	Night	48% 7% 11% 20% 12% 2	2731
	21st to end	Night	49% 8% 16% 19% 8% 1	2940
December	1st to 10th	Night	57% 9% 13% 17% 5%	4720
	11th to 20th	Night	59% 6% 10% 15% 10% 1	5348
	21st to end	Night	61% 6% 8% 13% 11% 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	27% 22% 32% 13% 5%	220
	11th to 20th	Day	31% 24% 33% 10% 1	220
	21st to end	Day	23% 28% 33% 11% 4	283
February	1st to 10th	Day	29% 29% 32% 9% 2	330
	11th to 20th	Day	31% 29% 30% 9% 1	469
	21st to end	Day	30% 24% 31% 13% 2	446
March	1st to 10th	Day	28% 23% 32% 15% 2	540
	11th to 20th	Day	33% 23% 28% 12% 4 1	540
	21st to end	Day	32% 25% 23% 14% 5% 1	594
April	1st to 10th	Day	35% 21% 24% 14% 5% 1	540
	11th to 20th	Day	32% 22% 22% 15% 6% 2	532
	21st to end	Day	29% 20% 30% 14% 6% 1	540
May	1st to 10th	Day	35% 16% 29% 12% 6% 2	543
	11th to 20th	Day	21% 15% 35% 21% 7% 1	567
	21st to end	Day	22% 13% 29% 23% 11% 3	617
June	1st to 10th	Day	20% 17% 28% 23% 11% 2	570
	11th to 20th	Day	18% 17% 30% 23% 10% 1	570
	21st to end	Day	18% 17% 33% 22% 9% 2	570
July	1st to 10th	Day	13% 9% 29% 30% 16% 3	565
	11th to 20th	Day	13% 10% 31% 29% 14% 3	564
	21st to end	Day	15% 8% 36% 27% 10% 3	620
August	1st to 10th	Day	10% 10% 27% 30% 19% 6%	566
	11th to 20th	Day	16% 9% 27% 26% 14% 7%	535
	21st to end	Day	12% 12% 28% 28% 14% 5%	583
September	1st to 10th	Day	16% 9% 24% 25% 17% 8%	530
	11th to 20th	Day	11% 9% 25% 21% 20% 14%	530
	21st to end	Day	19% 8% 28% 26% 13% 6%	530
October	1st to 10th	Day	24% 15% 27% 15% 15% 5%	530
	11th to 20th	Day	22% 17% 27% 24% 8% 2	530
	21st to end	Day	30% 14% 28% 22% 6% 1	476
November	1st to 10th	Day	26% 17% 27% 17% 12% 1	425
	11th to 20th	Day	27% 20% 26% 21% 5% 1	425
	21st to end	Day	35% 22% 28% 13% 2	220
December	1st to 10th	Day	30% 23% 30% 12% 4	220
	11th to 20th	Day	39% 18% 32% 9% 3	220
	21st to end	Day	30% 21% 29% 14% 4 1	242
January	1st to 10th	Night	23% 23% 35% 18% 2	840
	11th to 20th	Night	27% 20% 31% 20% 3	840
	21st to end	Night	18% 23% 35% 22% 2	924
February	1st to 10th	Night	21% 21% 37% 20% 1	840
	11th to 20th	Night	23% 24% 36% 15% 2	823
	21st to end	Night	27% 19% 34% 18% 2	692
March	1st to 10th	Night	24% 20% 35% 19% 2	840
	11th to 20th	Night	26% 21% 31% 18% 3	840
	21st to end	Night	23% 19% 33% 20% 4	924
April	1st to 10th	Night	28% 17% 32% 19% 3	840
	11th to 20th	Night	25% 18% 31% 21% 6%	831
	21st to end	Night	25% 17% 30% 22% 6%	761
May	1st to 10th	Night	28% 13% 30% 20% 8%	546
	11th to 20th	Night	20% 13% 30% 31% 6%	414
	21st to end	Night	20% 6% 26% 37% 12%	455
June	1st to 10th	Night	17% 9% 27% 32% 14% 1	420
	11th to 20th	Night	20% 10% 24% 35% 11%	420
	21st to end	Night	15% 6% 28% 38% 13%	420
July	1st to 10th	Night	12% 6% 22% 40% 19% 1	410
	11th to 20th	Night	14% 4 23% 39% 19% 1	408
	21st to end	Night	13% 4 24% 42% 18%	460
August	1st to 10th	Night	13% 3 21% 40% 21% 1	439
	11th to 20th	Night	16% 5% 22% 34% 20% 3	752
	21st to end	Night	17% 5% 22% 34% 21% 1	880
September	1st to 10th	Night	14% 7% 22% 37% 20% 1	800
	11th to 20th	Night	15% 6% 23% 30% 23% 4	800
	21st to end	Night	18% 8% 25% 32% 16% 2	800
October	1st to 10th	Night	24% 12% 22% 25% 16% 2	800
	11th to 20th	Night	21% 12% 27% 31% 9% 1	800
	21st to end	Night	26% 14% 30% 25% 5%	880
November	1st to 10th	Night	20% 15% 30% 28% 7%	820
	11th to 20th	Night	24% 19% 27% 24% 6% 1	840
	21st to end	Night	22% 20% 29% 23% 5%	840
December	1st to 10th	Night	25% 19% 35% 18% 3	840
	11th to 20th	Night	28% 20% 30% 18% 4	840
	21st to end	Night	28% 23% 28% 17% 3	924

Page generated at 2026-08-12 03:37:20. Version ac07

Copyright © 2026 Attilla Danko.