Bull Domingo Astro
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bull Domingo Astro clear sky chart from 2005-11-06 to 2025-08-05.

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	2 4 2 5% 4 4 5% 4 6% 8% 56%	129573
	Night	2 4 2 4 3 3 4 3 5% 8% 62%	127446
Transparency	Day	22% 7% 12% 23% 24% 11%	129281
	Night	19% 7% 12% 26% 26% 10%	127253
Seeing	Day	9% 13% 30% 27% 16% 5%	16484
	Night	5% 10% 34% 33% 15% 2	26493

By Month

Percentage Cloud Cover SW (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	2 3 7% 3 3 3 3 6% 7% 62%	3638
	11th to 20th	Day	2 1 5% 4 5% 3 3 5% 8% 64%	3987
	21st to end	Day	5% 3 6% 3 3 3 3 5% 7% 63%	4510
February	1st to 10th	Day	5% 3 6% 3 2 3 3 7% 8% 60%	1800
	11th to 20th	Day	1 3 2 5% 3 2 3 4 6% 8% 64%	1944
	21st to end	Day	5% 3 7% 3 3 4 3 5% 8% 61%	1650
March	1st to 10th	Day	4 3 6% 3 3 3 3 5% 7% 63%	4537
	11th to 20th	Day	1 8% 5% 8% 5% 5% 5% 5% 6% 6% 45%	5000
	21st to end	Day	1 4 2 5% 3 3 4 4 6% 10% 59%	5779
April	1st to 10th	Day	2 5% 2 5% 4 3 4 4 6% 8% 56%	2400
	11th to 20th	Day	4 7% 2 6% 4 5% 4 3 6% 7% 51%	2371
	21st to end	Day	4 6% 2 5% 5% 4 5% 5% 7% 8% 48%	2400
May	1st to 10th	Day	4 10% 3 6% 4 4 5% 4 6% 7% 47%	5530
	11th to 20th	Day	3 4 2 5% 4 4 5% 5% 7% 9% 53%	6183
	21st to end	Day	2 2 1 3 3 4 5% 5% 8% 10% 54%	6925
June	1st to 10th	Day	3 3 1 5% 3 4 5% 6% 9% 11% 49%	2800
	11th to 20th	Day	3 3 4 3 4 5% 5% 7% 9% 58%	2800
	21st to end	Day	2 3 1 4 5% 5% 7% 6% 8% 9% 49%	2800
July	1st to 10th	Day	2 2 1 3 3 4 5% 4 6% 9% 60%	6339
	11th to 20th	Day	2 2 1 5% 6% 7% 7% 7% 8% 10% 44%	6340
	21st to end	Day	4 3 2 6% 6% 7% 7% 6% 8% 10% 42%	6495
August	1st to 10th	Day	3 4 2 7% 6% 8% 8% 7% 9% 10% 38%	4098
	11th to 20th	Day	3 3 1 4 4 5% 7% 6% 9% 10% 49%	3726
	21st to end	Day	5% 5% 2 5% 4 6% 7% 6% 8% 11% 42%	4180
September	1st to 10th	Day	4 4 2 4 4 4 5% 4 7% 8% 53%	2280
	11th to 20th	Day	4 2 1 4 3 3 4 4 5% 7% 62%	2271
	21st to end	Day	4 2 1 5% 3 3 3 3 3 5% 67%	2089
October	1st to 10th	Day	2 2 1 3 2 3 3 2 3 4 75%	3170
	11th to 20th	Day	2 3 1 4 3 2 4 4 5% 9% 64%	3150
	21st to end	Day	2 3 1 2 2 2 2 2 4 7% 74%	3418
November	1st to 10th	Day	1 4 2 3 2 2 3 2 5% 7% 70%	1763
	11th to 20th	Day	3 1 3 2 2 3 3 4 8% 71%	1800
	21st to end	Day	1 4 2 5% 4 2 3 2 5% 7% 67%	1750
December	1st to 10th	Day	3 1 3 2 2 2 2 4 6% 74%	2620
	11th to 20th	Day	2 1 3 2 2 3 3 6% 9% 69%	3026
	21st to end	Day	3 2 6% 3 4 4 4 6% 7% 62%	4004
January	1st to 10th	Night	3 3 8% 4 3 4 3 5% 8% 60%	6327
	11th to 20th	Night	2 1 3 2 3 4 3 5% 7% 70%	6036
	21st to end	Night	3 2 4 3 3 3 3 4 7% 66%	6468
February	1st to 10th	Night	1 4 3 6% 4 3 2 2 4 7% 65%	2600
	11th to 20th	Night	1 4 2 5% 4 4 4 4 5% 7% 62%	2341
	21st to end	Night	3 2 6% 3 2 3 3 5% 6% 66%	1980
March	1st to 10th	Night	6% 3 5% 2 3 3 2 4 6% 66%	5335
	11th to 20th	Night	1 7% 3 5% 3 2 3 4 4 6% 61%	5000
	21st to end	Night	1 5% 2 4 3 3 3 3 5% 7% 66%	5180
April	1st to 10th	Night	1 5% 2 5% 3 3 3 3 5% 8% 63%	2000
	11th to 20th	Night	3 7% 2 5% 3 3 3 3 4 7% 58%	1977
	21st to end	Night	3 6% 3 5% 4 4 4 4 5% 8% 56%	2000
May	1st to 10th	Night	4 7% 2 6% 4 4 4 3 5% 7% 52%	4448
	11th to 20th	Night	5% 5% 2 3 2 3 3 3 5% 8% 60%	3716
	21st to end	Night	4 3 1 4 3 3 3 4 5% 7% 62%	3972
June	1st to 10th	Night	4 4 1 4 3 3 3 4 7% 8% 59%	1600
	11th to 20th	Night	2 3 1 3 2 3 4 3 5% 8% 68%	1600
	21st to end	Night	2 3 1 5% 4 5% 5% 5% 8% 9% 52%	1600
July	1st to 10th	Night	2 3 1 4 3 4 5% 5% 7% 10% 56%	3640
	11th to 20th	Night	2 2 1 4 4 5% 7% 7% 11% 14% 44%	3640
	21st to end	Night	2 4 2 6% 5% 5% 6% 5% 9% 11% 45%	4373
August	1st to 10th	Night	4 5% 2 7% 6% 6% 7% 6% 10% 11% 36%	2930
	11th to 20th	Night	2 3 1 4 3 5% 5% 6% 11% 13% 47%	3113
	21st to end	Night	3 5% 2 6% 5% 5% 6% 6% 9% 12% 42%	3487
September	1st to 10th	Night	4 5% 1 5% 4 5% 4 4 6% 9% 53%	1900
	11th to 20th	Night	4 4 1 3 3 3 3 3 5% 7% 63%	1907
	21st to end	Night	4 3 1 4 3 2 3 3 4 7% 66%	2090
October	1st to 10th	Night	2 2 1 3 2 2 2 2 3 5% 75%	3797
	11th to 20th	Night	2 3 1 4 3 3 4 3 5% 7% 65%	3778
	21st to end	Night	2 3 1 3 2 2 2 2 3 5% 76%	4120
November	1st to 10th	Night	1 3 2 3 2 2 2 3 4 7% 71%	2521
	11th to 20th	Night	1 2 1 3 2 2 3 3 4 5% 75%	2600
	21st to end	Night	1 5% 2 3 2 2 2 2 5% 7% 67%	2645
December	1st to 10th	Night	2 1 4 2 2 2 2 3 6% 76%	4570
	11th to 20th	Night	1 2 1 3 2 2 2 2 4 7% 72%	5181
	21st to end	Night	3 2 6% 4 4 4 4 6% 8% 60%	6974

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	18% 4 13% 29% 26% 9%	3639
	11th to 20th	Day	16% 6% 12% 26% 27% 14%	3987
	21st to end	Day	21% 5% 8% 28% 27% 12%	4510
February	1st to 10th	Day	22% 4 13% 27% 22% 11%	1800
	11th to 20th	Day	18% 5% 11% 27% 29% 10%	1954
	21st to end	Day	21% 5% 10% 21% 27% 16%	1650
March	1st to 10th	Day	17% 5% 9% 15% 36% 19%	4537
	11th to 20th	Day	32% 7% 11% 23% 22% 6%	5000
	21st to end	Day	18% 6% 11% 44% 18% 3	5779
April	1st to 10th	Day	24% 5% 13% 23% 23% 12%	2400
	11th to 20th	Day	31% 5% 9% 25% 20% 10%	2374
	21st to end	Day	30% 6% 14% 24% 21% 6%	2400
May	1st to 10th	Day	31% 9% 11% 22% 19% 9%	5530
	11th to 20th	Day	23% 8% 12% 22% 23% 12%	6187
	21st to end	Day	18% 9% 12% 21% 28% 12%	6926
June	1st to 10th	Day	24% 10% 14% 22% 20% 10%	2800
	11th to 20th	Day	20% 7% 10% 16% 25% 22%	2800
	21st to end	Day	25% 9% 13% 19% 20% 13%	2800
July	1st to 10th	Day	18% 8% 10% 15% 23% 26%	6271
	11th to 20th	Day	28% 12% 17% 26% 13% 5%	6265
	21st to end	Day	31% 12% 16% 16% 15% 9%	6308
August	1st to 10th	Day	35% 13% 19% 18% 11% 4	4084
	11th to 20th	Day	26% 11% 15% 17% 20% 11%	3762
	21st to end	Day	30% 11% 17% 19% 20% 4	4179
September	1st to 10th	Day	26% 8% 11% 21% 22% 12%	2280
	11th to 20th	Day	20% 6% 12% 18% 29% 15%	2271
	21st to end	Day	20% 4 8% 24% 33% 11%	2089
October	1st to 10th	Day	14% 4 6% 16% 36% 24%	3170
	11th to 20th	Day	16% 5% 12% 29% 30% 9%	3150
	21st to end	Day	12% 3 7% 21% 43% 15%	3418
November	1st to 10th	Day	14% 4 10% 21% 37% 13%	1763
	11th to 20th	Day	13% 4 10% 31% 31% 11%	1800
	21st to end	Day	20% 2 9% 22% 32% 15%	1750
December	1st to 10th	Day	12% 4 11% 31% 34% 9%	2620
	11th to 20th	Day	12% 4 12% 30% 32% 10%	3024
	21st to end	Day	17% 7% 10% 27% 26% 12%	4004
January	1st to 10th	Night	21% 4 10% 30% 28% 8%	6327
	11th to 20th	Night	11% 5% 10% 31% 29% 14%	6036
	21st to end	Night	17% 6% 11% 27% 27% 12%	6468
February	1st to 10th	Night	21% 3 12% 30% 22% 12%	2600
	11th to 20th	Night	21% 5% 11% 29% 26% 8%	2341
	21st to end	Night	18% 4 9% 24% 33% 13%	1980
March	1st to 10th	Night	19% 4 7% 18% 39% 13%	5335
	11th to 20th	Night	22% 6% 10% 24% 32% 6%	5000
	21st to end	Night	17% 6% 12% 44% 18% 2	5180
April	1st to 10th	Night	18% 5% 14% 28% 26% 8%	2000
	11th to 20th	Night	26% 6% 10% 26% 25% 7%	1977
	21st to end	Night	26% 6% 13% 30% 20% 5%	2000
May	1st to 10th	Night	27% 9% 13% 27% 17% 7%	4445
	11th to 20th	Night	22% 7% 11% 30% 21% 9%	3717
	21st to end	Night	17% 10% 14% 20% 28% 11%	3972
June	1st to 10th	Night	22% 9% 18% 22% 17% 13%	1600
	11th to 20th	Night	15% 7% 11% 22% 24% 21%	1600
	21st to end	Night	25% 8% 13% 19% 21% 14%	1600
July	1st to 10th	Night	19% 11% 13% 20% 24% 13%	3600
	11th to 20th	Night	23% 15% 27% 23% 10% 3	3592
	21st to end	Night	28% 15% 19% 18% 15% 5%	4248
August	1st to 10th	Night	35% 15% 22% 15% 9% 5%	2921
	11th to 20th	Night	23% 12% 26% 16% 18% 5%	3143
	21st to end	Night	31% 11% 18% 23% 14% 3	3487
September	1st to 10th	Night	26% 7% 14% 24% 21% 7%	1900
	11th to 20th	Night	19% 7% 12% 20% 26% 15%	1907
	21st to end	Night	19% 5% 11% 24% 34% 8%	2090
October	1st to 10th	Night	13% 4 8% 25% 35% 15%	3797
	11th to 20th	Night	16% 7% 12% 28% 28% 9%	3778
	21st to end	Night	13% 3 5% 26% 38% 14%	4120
November	1st to 10th	Night	13% 4 11% 25% 34% 14%	2521
	11th to 20th	Night	12% 4 9% 32% 30% 13%	2600
	21st to end	Night	17% 5% 10% 22% 33% 14%	2645
December	1st to 10th	Night	11% 4 10% 37% 30% 9%	4570
	11th to 20th	Night	12% 3 10% 28% 38% 8%	5182
	21st to end	Night	19% 7% 12% 23% 28% 10%	6974

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% 17% 35% 21% 9% 4	300
	11th to 20th	Day	14% 16% 38% 26% 5% 1	300
	21st to end	Day	5% 15% 42% 26% 9% 3	330
February	1st to 10th	Day	10% 25% 45% 16% 2 1	300
	11th to 20th	Day	9% 30% 40% 16% 3 1	300
	21st to end	Day	16% 20% 39% 20% 5%	249
March	1st to 10th	Day	13% 20% 37% 21% 8% 1	311
	11th to 20th	Day	12% 23% 34% 22% 8% 1	500
	21st to end	Day	15% 26% 36% 18% 4 1	550
April	1st to 10th	Day	15% 24% 34% 20% 5% 1	500
	11th to 20th	Day	17% 27% 36% 15% 5% 1	492
	21st to end	Day	14% 23% 39% 16% 7% 1	500
May	1st to 10th	Day	14% 18% 36% 21% 9% 1	541
	11th to 20th	Day	12% 12% 27% 31% 15% 3	725
	21st to end	Day	8% 14% 30% 28% 16% 4	789
June	1st to 10th	Day	6% 9% 27% 31% 22% 7%	730
	11th to 20th	Day	5% 10% 32% 32% 17% 6%	730
	21st to end	Day	4 8% 29% 30% 23% 7%	730
July	1st to 10th	Day	7% 3 18% 37% 26% 9%	721
	11th to 20th	Day	4 2 13% 36% 35% 10%	718
	21st to end	Day	7% 3 12% 34% 32% 12%	617
August	1st to 10th	Day	6% 3 17% 36% 26% 12%	504
	11th to 20th	Day	5% 1 22% 38% 25% 8%	477
	21st to end	Day	8% 3 20% 36% 24% 8%	539
September	1st to 10th	Day	6% 5% 22% 32% 25% 9%	490
	11th to 20th	Day	6% 9% 30% 33% 19% 4	481
	21st to end	Day	7% 7% 21% 29% 28% 8%	300
October	1st to 10th	Day	9% 10% 26% 23% 24% 8%	300
	11th to 20th	Day	8% 14% 30% 28% 14% 5%	300
	21st to end	Day	12% 14% 30% 28% 14% 3	330
November	1st to 10th	Day	8% 20% 31% 26% 12% 3	300
	11th to 20th	Day	5% 19% 40% 23% 8% 4	300
	21st to end	Day	6% 16% 38% 31% 7% 2	300
December	1st to 10th	Day	11% 19% 34% 24% 10% 2	300
	11th to 20th	Day	8% 22% 40% 19% 9% 2	300
	21st to end	Day	11% 23% 43% 18% 4 1	330
January	1st to 10th	Night	5% 17% 38% 29% 10% 2	1000
	11th to 20th	Night	5% 18% 40% 27% 8% 2	865
	21st to end	Night	3 11% 46% 32% 8% 1	880
February	1st to 10th	Night	4 13% 54% 25% 5%	800
	11th to 20th	Night	5% 14% 53% 22% 6%	784
	21st to end	Night	3 13% 54% 27% 2	660
March	1st to 10th	Night	6% 17% 43% 28% 6% 1	800
	11th to 20th	Night	6% 8% 42% 33% 11% 1	800
	21st to end	Night	6% 13% 45% 32% 4	752
April	1st to 10th	Night	8% 12% 46% 29% 6%	600
	11th to 20th	Night	9% 13% 41% 30% 6% 1	593
	21st to end	Night	8% 12% 36% 34% 10% 1	600
May	1st to 10th	Night	9% 10% 31% 39% 10% 1	600
	11th to 20th	Night	12% 6% 27% 37% 16% 2	591
	21st to end	Night	9% 10% 29% 34% 15% 2	650
June	1st to 10th	Night	6% 6% 21% 41% 24% 2	600
	11th to 20th	Night	3 6% 27% 45% 17% 2	600
	21st to end	Night	3 5% 20% 40% 29% 3	600
July	1st to 10th	Night	7% 2 10% 39% 36% 5%	585
	11th to 20th	Night	5% 1 5% 39% 41% 9%	582
	21st to end	Night	5% 2 4 33% 49% 6%	657
August	1st to 10th	Night	7% 2 7% 35% 39% 9%	579
	11th to 20th	Night	6% 1 10% 42% 34% 6%	564
	21st to end	Night	5% 2 11% 41% 35% 6%	627
September	1st to 10th	Night	5% 3 13% 42% 30% 7%	570
	11th to 20th	Night	6% 4 24% 38% 23% 5%	570
	21st to end	Night	5% 6% 26% 38% 22% 4	570
October	1st to 10th	Night	6% 7% 27% 40% 17% 3	757
	11th to 20th	Night	3 7% 34% 38% 16% 3	760
	21st to end	Night	5% 6% 37% 33% 15% 3	836
November	1st to 10th	Night	3 10% 38% 34% 13% 2	961
	11th to 20th	Night	4 11% 42% 30% 10% 2	1000
	21st to end	Night	6% 10% 38% 34% 10% 1	1000
December	1st to 10th	Night	3 15% 41% 32% 8% 1	1000
	11th to 20th	Night	5% 14% 48% 25% 8% 1	1000
	21st to end	Night	6% 19% 45% 25% 5% 1	1100

Page generated at 2025-08-01 23:32:24. Version ac07

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