Badlands Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Badlands Observatory clear sky chart from 2005-11-06 to 2024-11-06.

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	8% 5% 2 5% 4 4 4 3 6% 8% 52%	105241
	Night	7% 6% 2 6% 4 4 4 4 6% 7% 50%	102518
Transparency	Day	30% 7% 15% 27% 17% 4	104985
	Night	31% 7% 14% 26% 17% 4	102364
Seeing	Day	10% 8% 28% 32% 17% 4	15932
	Night	10% 8% 33% 39% 11%	25870

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 6% 3 10% 7% 5% 4 4 5% 8% 47%	2538
	11th to 20th	Day	3 7% 4 10% 6% 6% 3 3 4 8% 47%	2540
	21st to end	Day	3 6% 2 8% 6% 4 4 4 5% 7% 50%	2794
February	1st to 10th	Day	7% 11% 4 8% 6% 6% 5% 4 5% 6% 37%	1668
	11th to 20th	Day	6% 10% 4 6% 4 4 6% 4 6% 7% 44%	1849
	21st to end	Day	4 9% 3 8% 6% 5% 5% 4 5% 6% 45%	1570
March	1st to 10th	Day	6% 6% 2 6% 4 4 4 3 5% 8% 53%	3130
	11th to 20th	Day	6% 6% 2 4 3 3 4 3 5% 8% 56%	3283
	21st to end	Day	16% 10% 4 8% 4 4 4 3 5% 7% 35%	4093
April	1st to 10th	Day	12% 9% 2 5% 4 3 4 3 6% 8% 43%	2280
	11th to 20th	Day	12% 7% 2 7% 5% 5% 5% 4 6% 7% 41%	2258
	21st to end	Day	13% 6% 2 6% 4 5% 5% 3 6% 8% 42%	2470
May	1st to 10th	Day	16% 7% 2 7% 4 4 5% 4 5% 7% 39%	4120
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 6% 9% 49%	4344
	21st to end	Day	14% 6% 2 5% 4 4 4 4 6% 7% 43%	4825
June	1st to 10th	Day	9% 5% 1 4 4 3 4 4 6% 9% 52%	2660
	11th to 20th	Day	9% 4 1 4 3 3 4 4 7% 9% 52%	2660
	21st to end	Day	5% 3 1 3 3 3 3 3 6% 9% 60%	2660
July	1st to 10th	Day	4 3 1 5% 4 4 4 4 7% 8% 55%	4430
	11th to 20th	Day	4 2 1 3 3 3 3 4 6% 9% 61%	4430
	21st to end	Day	3 2 1 3 3 3 4 4 6% 9% 62%	4802
August	1st to 10th	Day	5% 4 2 5% 4 4 5% 4 7% 9% 52%	4350
	11th to 20th	Day	7% 4 1 4 4 4 5% 4 6% 9% 53%	3977
	21st to end	Day	5% 3 1 3 3 3 3 3 5% 7% 64%	4180
September	1st to 10th	Day	7% 4 1 4 2 3 3 2 4 7% 63%	2280
	11th to 20th	Day	7% 3 1 4 3 2 3 3 4 7% 61%	2147
	21st to end	Day	10% 3 1 3 2 2 2 2 4 7% 63%	2090
October	1st to 10th	Day	7% 4 1 3 2 2 2 2 2 4 71%	3453
	11th to 20th	Day	8% 4 1 5% 3 3 3 3 4 7% 59%	2996
	21st to end	Day	10% 6% 2 6% 4 4 4 4 6% 8% 47%	3091
November	1st to 10th	Day	6% 6% 2 5% 4 4 5% 3 5% 7% 54%	1718
	11th to 20th	Day	6% 5% 2 6% 4 4 4 4 6% 7% 51%	1710
	21st to end	Day	5% 9% 3 5% 4 4 4 4 5% 9% 50%	1605
December	1st to 10th	Day	5% 8% 3 8% 4 4 4 5% 6% 7% 46%	1520
	11th to 20th	Day	3 5% 2 6% 5% 3 5% 4 6% 9% 51%	1926
	21st to end	Day	8% 12% 4 6% 5% 4 4 3 5% 6% 44%	2794
January	1st to 10th	Night	3 7% 3 11% 6% 5% 4 4 5% 7% 44%	4417
	11th to 20th	Night	3 7% 3 8% 6% 6% 6% 4 6% 7% 44%	4430
	21st to end	Night	2 6% 3 7% 4 4 5% 4 6% 8% 51%	4873
February	1st to 10th	Night	8% 10% 3 8% 5% 5% 4 4 6% 6% 40%	2527
	11th to 20th	Night	4 9% 3 9% 5% 6% 4 4 6% 7% 42%	2218
	21st to end	Night	6% 8% 3 7% 5% 5% 4 3 6% 7% 46%	1884
March	1st to 10th	Night	9% 8% 3 7% 4 3 4 4 5% 7% 46%	3734
	11th to 20th	Night	6% 6% 2 5% 3 3 4 3 6% 10% 52%	3682
	21st to end	Night	13% 10% 4 8% 5% 4 4 4 6% 8% 34%	3544
April	1st to 10th	Night	13% 6% 2 6% 4 4 4 4 6% 8% 41%	1900
	11th to 20th	Night	12% 8% 3 6% 5% 4 4 3 5% 6% 45%	1868
	21st to end	Night	13% 7% 2 6% 5% 4 4 4 5% 8% 43%	1710
May	1st to 10th	Night	12% 6% 2 7% 4 5% 5% 4 6% 8% 41%	2850
	11th to 20th	Night	8% 3 2 4 3 3 4 4 7% 9% 54%	2558
	21st to end	Night	15% 6% 2 6% 4 4 5% 4 6% 7% 42%	2762
June	1st to 10th	Night	9% 4 2 4 3 4 4 4 6% 9% 52%	1520
	11th to 20th	Night	10% 4 2 5% 4 4 3 4 6% 9% 49%	1520
	21st to end	Night	6% 4 1 4 3 4 5% 4 6% 8% 56%	1520
July	1st to 10th	Night	6% 3 1 4 4 4 5% 5% 7% 8% 55%	2540
	11th to 20th	Night	4 2 1 4 3 3 4 4 6% 8% 60%	2540
	21st to end	Night	3 3 1 4 3 3 3 4 6% 8% 62%	2761
August	1st to 10th	Night	5% 4 2 6% 4 5% 5% 5% 6% 9% 49%	2589
	11th to 20th	Night	7% 4 2 5% 4 4 4 4 7% 9% 51%	2857
	21st to end	Night	3 3 1 5% 3 4 5% 4 6% 8% 59%	3487
September	1st to 10th	Night	6% 3 1 3 3 2 3 3 4 7% 64%	1900
	11th to 20th	Night	7% 3 2 4 2 3 4 4 5% 7% 60%	2033
	21st to end	Night	10% 3 1 4 3 2 3 2 4 6% 62%	2090
October	1st to 10th	Night	8% 3 1 3 2 2 2 2 3 4 70%	3506
	11th to 20th	Night	7% 4 2 4 3 3 3 3 5% 7% 59%	3900
	21st to end	Night	10% 6% 1 5% 3 4 4 3 5% 8% 50%	4467
November	1st to 10th	Night	7% 6% 2 6% 4 3 5% 4 6% 8% 49%	2483
	11th to 20th	Night	6% 6% 2 7% 4 4 5% 3 5% 7% 50%	2470
	21st to end	Night	5% 7% 2 5% 4 3 4 4 6% 7% 53%	2574
December	1st to 10th	Night	5% 8% 2 6% 4 4 4 4 6% 7% 48%	2660
	11th to 20th	Night	4 6% 2 5% 5% 5% 5% 4 6% 8% 51%	3271
	21st to end	Night	9% 12% 3 6% 4 4 4 3 5% 6% 43%	4873

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	34% 8% 19% 27% 12%	2539
	11th to 20th	Day	36% 10% 17% 23% 10% 3	2540
	21st to end	Day	31% 9% 20% 27% 12% 1	2794
February	1st to 10th	Day	45% 8% 13% 20% 12% 2	1668
	11th to 20th	Day	38% 8% 17% 20% 13% 4	1859
	21st to end	Day	37% 8% 14% 26% 12% 3	1570
March	1st to 10th	Day	29% 6% 12% 25% 23% 4	3130
	11th to 20th	Day	25% 8% 17% 38% 12% 1	3283
	21st to end	Day	47% 9% 20% 18% 6%	4093
April	1st to 10th	Day	37% 6% 17% 28% 10% 3	2280
	11th to 20th	Day	40% 8% 14% 22% 14% 2	2261
	21st to end	Day	38% 8% 15% 28% 10%	2470
May	1st to 10th	Day	41% 9% 14% 24% 11% 2	4120
	11th to 20th	Day	30% 9% 16% 29% 14% 3	4348
	21st to end	Day	35% 11% 17% 25% 11% 1	4825
June	1st to 10th	Day	28% 9% 20% 27% 14% 2	2660
	11th to 20th	Day	27% 9% 17% 27% 17% 3	2660
	21st to end	Day	19% 7% 15% 32% 21% 6%	2660
July	1st to 10th	Day	25% 5% 14% 31% 23% 2	4361
	11th to 20th	Day	20% 4 13% 31% 24% 8%	4355
	21st to end	Day	18% 5% 12% 27% 29% 9%	4651
August	1st to 10th	Day	27% 5% 18% 22% 21% 6%	4335
	11th to 20th	Day	28% 5% 16% 28% 18% 4	4016
	21st to end	Day	21% 3 11% 27% 26% 12%	4179
September	1st to 10th	Day	22% 4 9% 28% 27% 9%	2280
	11th to 20th	Day	23% 5% 11% 29% 24% 8%	2147
	21st to end	Day	23% 4 10% 32% 27% 4	2090
October	1st to 10th	Day	20% 3 9% 21% 32% 16%	3453
	11th to 20th	Day	26% 3 12% 36% 21% 3	2996
	21st to end	Day	35% 4 13% 28% 15% 4	3091
November	1st to 10th	Day	29% 7% 14% 25% 19% 6%	1718
	11th to 20th	Day	30% 6% 12% 28% 20% 4	1710
	21st to end	Day	30% 6% 16% 29% 15% 4	1605
December	1st to 10th	Day	34% 8% 15% 26% 15% 2	1520
	11th to 20th	Day	27% 9% 20% 33% 10% 1	1924
	21st to end	Day	41% 6% 11% 30% 12% 1	2794
January	1st to 10th	Night	38% 7% 13% 31% 10% 1	4417
	11th to 20th	Night	36% 11% 16% 24% 12% 1	4430
	21st to end	Night	30% 9% 19% 28% 13% 1	4873
February	1st to 10th	Night	43% 7% 15% 22% 12% 1	2527
	11th to 20th	Night	40% 8% 13% 24% 12% 3	2218
	21st to end	Night	35% 6% 16% 25% 12% 5%	1884
March	1st to 10th	Night	34% 8% 12% 24% 20% 1	3734
	11th to 20th	Night	26% 7% 18% 31% 17% 1	3682
	21st to end	Night	44% 12% 20% 17% 6% 1	3544
April	1st to 10th	Night	39% 9% 15% 23% 13% 2	1900
	11th to 20th	Night	40% 7% 13% 23% 15% 2	1868
	21st to end	Night	38% 8% 14% 25% 13% 1	1710
May	1st to 10th	Night	36% 13% 14% 22% 13% 3	2850
	11th to 20th	Night	23% 10% 19% 35% 12% 1	2559
	21st to end	Night	37% 10% 14% 27% 12% 1	2762
June	1st to 10th	Night	28% 10% 18% 28% 15% 2	1520
	11th to 20th	Night	31% 9% 19% 23% 15% 3	1520
	21st to end	Night	23% 8% 15% 29% 19% 5%	1520
July	1st to 10th	Night	26% 5% 18% 22% 25% 4	2500
	11th to 20th	Night	21% 4 14% 32% 22% 7%	2492
	21st to end	Night	21% 4 14% 29% 24% 8%	2674
August	1st to 10th	Night	31% 6% 16% 22% 19% 6%	2581
	11th to 20th	Night	30% 5% 19% 23% 19% 3	2884
	21st to end	Night	24% 6% 13% 24% 26% 8%	3487
September	1st to 10th	Night	21% 4 9% 28% 28% 9%	1900
	11th to 20th	Night	22% 7% 14% 26% 26% 6%	2033
	21st to end	Night	25% 5% 8% 30% 26% 7%	2090
October	1st to 10th	Night	20% 4 7% 19% 31% 19%	3506
	11th to 20th	Night	26% 4 10% 34% 22% 4	3900
	21st to end	Night	32% 4 12% 26% 19% 7%	4467
November	1st to 10th	Night	31% 7% 13% 25% 18% 6%	2483
	11th to 20th	Night	33% 6% 13% 24% 20% 5%	2470
	21st to end	Night	28% 7% 16% 27% 18% 3	2574
December	1st to 10th	Night	34% 8% 14% 28% 14% 2	2660
	11th to 20th	Night	29% 6% 15% 34% 13% 2	3272
	21st to end	Night	39% 7% 13% 28% 11% 2	4873

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	6% 6% 33% 29% 22% 4	270
	11th to 20th	Day	14% 9% 31% 33% 11% 2	270
	21st to end	Day	8% 11% 40% 28% 11% 1	297
February	1st to 10th	Day	11% 11% 39% 31% 7%	270
	11th to 20th	Day	13% 11% 36% 31% 8% 1	270
	21st to end	Day	9% 12% 41% 28% 8% 2	225
March	1st to 10th	Day	10% 14% 34% 27% 12% 3	270
	11th to 20th	Day	9% 11% 31% 32% 14% 3	270
	21st to end	Day	19% 12% 32% 22% 12% 3	460
April	1st to 10th	Day	16% 14% 35% 27% 7% 1	460
	11th to 20th	Day	19% 19% 31% 24% 7% 1	459
	21st to end	Day	16% 11% 25% 34% 14% 1	650
May	1st to 10th	Day	15% 10% 27% 28% 16% 3	653
	11th to 20th	Day	19% 7% 22% 30% 17% 5%	675
	21st to end	Day	15% 9% 29% 28% 15% 4	734
June	1st to 10th	Day	6% 8% 23% 33% 22% 9%	680
	11th to 20th	Day	11% 7% 30% 35% 14% 4	680
	21st to end	Day	6% 6% 25% 37% 23% 4	680
July	1st to 10th	Day	5% 2 21% 40% 26% 6%	671
	11th to 20th	Day	5% 3 23% 45% 21% 3	668
	21st to end	Day	5% 2 19% 44% 27% 4	739
August	1st to 10th	Day	5% 3 21% 42% 24% 4	676
	11th to 20th	Day	7% 3 21% 39% 24% 6%	627
	21st to end	Day	5% 6% 23% 32% 26% 7%	539
September	1st to 10th	Day	6% 6% 25% 31% 25% 6%	490
	11th to 20th	Day	9% 5% 18% 33% 27% 8%	357
	21st to end	Day	13% 10% 26% 28% 17% 6%	300
October	1st to 10th	Day	15% 8% 23% 24% 18% 12%	300
	11th to 20th	Day	14% 11% 33% 23% 15% 4	300
	21st to end	Day	13% 14% 32% 25% 14% 2	330
November	1st to 10th	Day	11% 9% 37% 27% 14% 2	285
	11th to 20th	Day	12% 12% 31% 29% 14% 2	270
	21st to end	Day	12% 9% 30% 34% 13% 1	270
December	1st to 10th	Day	8% 12% 41% 28% 9% 2	270
	11th to 20th	Day	9% 7% 43% 31% 9% 1	270
	21st to end	Day	10% 13% 36% 27% 13% 1	297
January	1st to 10th	Night	6% 10% 35% 37% 12% 1	950
	11th to 20th	Night	8% 13% 34% 35% 9% 1	950
	21st to end	Night	9% 10% 37% 36% 8%	1045
February	1st to 10th	Night	13% 9% 39% 33% 7%	853
	11th to 20th	Night	8% 8% 41% 35% 7% 1	744
	21st to end	Night	10% 8% 39% 35% 8% 1	628
March	1st to 10th	Night	11% 10% 35% 37% 7% 1	760
	11th to 20th	Night	10% 7% 33% 40% 9% 1	694
	21st to end	Night	15% 11% 30% 33% 10% 1	627
April	1st to 10th	Night	15% 9% 35% 36% 5%	570
	11th to 20th	Night	18% 12% 34% 33% 4	563
	21st to end	Night	16% 11% 28% 35% 11%	570
May	1st to 10th	Night	12% 8% 32% 35% 13% 1	570
	11th to 20th	Night	14% 8% 25% 39% 13%	561
	21st to end	Night	17% 8% 35% 29% 12%	617
June	1st to 10th	Night	8% 6% 31% 38% 16% 1	570
	11th to 20th	Night	11% 6% 35% 40% 8% 1	570
	21st to end	Night	5% 6% 30% 47% 12%	570
July	1st to 10th	Night	4 3 30% 44% 19% 1	555
	11th to 20th	Night	3 3 28% 51% 14%	552
	21st to end	Night	3 2 27% 55% 13%	624
August	1st to 10th	Night	6% 2 26% 51% 14%	567
	11th to 20th	Night	5% 2 28% 48% 16% 1	564
	21st to end	Night	5% 3 28% 48% 16%	627
September	1st to 10th	Night	7% 4 26% 46% 16% 1	570
	11th to 20th	Night	8% 3 27% 43% 17% 1	570
	21st to end	Night	11% 8% 27% 39% 15% 1	570
October	1st to 10th	Night	16% 6% 29% 33% 16%	583
	11th to 20th	Night	12% 7% 33% 36% 12% 1	831
	21st to end	Night	13% 9% 32% 36% 10% 1	1045
November	1st to 10th	Night	10% 6% 34% 41% 8%	955
	11th to 20th	Night	10% 9% 34% 38% 9%	950
	21st to end	Night	7% 10% 35% 38% 10%	950
December	1st to 10th	Night	9% 10% 37% 35% 9%	950
	11th to 20th	Night	8% 8% 37% 38% 10%	950
	21st to end	Night	13% 11% 32% 33% 10%	1045

Page generated at 2024-11-03 11:19:00. Version ac07

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