Oglala Lakota College - Piya Wiconi
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oglala Lakota College - Piya Wiconi clear sky chart from 2005-11-06 to 2026-02-01.

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% 6% 2 5% 4 4 4 3 5% 7% 51%	136239
	Night	7% 7% 3 6% 4 4 4 4 6% 7% 49%	133163
Transparency	Day	31% 6% 13% 27% 18% 4	131020
	Night	33% 6% 13% 26% 18% 4	129402
Seeing	Day	11% 8% 30% 32% 15% 3	17544
	Night	10% 7% 38% 35% 8%	27626

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	3 9% 4 12% 6% 5% 4 4 6% 8% 40%	3718
	11th to 20th	Day	3 10% 4 11% 5% 5% 5% 4 5% 7% 40%	3720
	21st to end	Day	3 5% 2 7% 5% 5% 4 3 4 7% 55%	4092
February	1st to 10th	Day	7% 13% 4 10% 5% 5% 4 3 5% 6% 38%	1795
	11th to 20th	Day	7% 10% 4 8% 5% 3 5% 4 5% 7% 42%	1949
	21st to end	Day	5% 9% 3 7% 4 4 4 4 6% 8% 47%	1650
March	1st to 10th	Day	7% 9% 2 5% 4 3 3 2 4 6% 55%	4500
	11th to 20th	Day	7% 7% 2 3 3 3 3 3 5% 9% 55%	4689
	21st to end	Day	13% 10% 4 9% 4 4 5% 3 5% 8% 35%	5875
April	1st to 10th	Day	13% 10% 2 6% 4 3 4 3 5% 7% 44%	2400
	11th to 20th	Day	15% 10% 2 7% 3 4 4 4 5% 7% 40%	2371
	21st to end	Day	15% 9% 2 5% 4 3 4 3 6% 7% 42%	2590
May	1st to 10th	Day	12% 6% 2 6% 4 4 4 3 5% 7% 49%	5900
	11th to 20th	Day	14% 7% 2 6% 4 4 4 3 5% 7% 44%	6183
	21st to end	Day	17% 6% 2 5% 3 4 4 3 5% 7% 44%	6925
June	1st to 10th	Day	9% 4 1 4 4 4 4 4 6% 10% 50%	2800
	11th to 20th	Day	9% 4 2 4 3 3 4 4 7% 8% 52%	2800
	21st to end	Day	5% 3 1 4 3 4 3 3 6% 8% 61%	2800
July	1st to 10th	Day	6% 4 2 4 3 4 4 4 6% 8% 54%	6339
	11th to 20th	Day	7% 3 2 4 3 3 4 3 6% 9% 57%	6340
	21st to end	Day	7% 3 1 4 3 4 4 4 6% 8% 56%	6903
August	1st to 10th	Day	4 4 2 5% 3 4 4 4 6% 9% 55%	6109
	11th to 20th	Day	4 3 2 4 3 3 4 3 5% 8% 61%	5649
	21st to end	Day	8% 4 2 5% 4 4 4 4 6% 8% 52%	5984
September	1st to 10th	Day	5% 4 1 4 3 3 3 3 4 6% 65%	2400
	11th to 20th	Day	8% 3 1 3 3 3 3 3 4 6% 63%	2260
	21st to end	Day	9% 4 1 3 2 2 3 2 4 6% 63%	2200
October	1st to 10th	Day	7% 4 1 2 2 2 2 2 3 4 71%	3563
	11th to 20th	Day	10% 5% 1 4 3 2 2 2 4 8% 59%	3105
	21st to end	Day	9% 8% 2 5% 4 4 3 3 4 7% 50%	3190
November	1st to 10th	Day	7% 6% 2 4 3 4 4 4 6% 8% 53%	1853
	11th to 20th	Day	5% 7% 2 6% 4 3 4 4 5% 7% 52%	1890
	21st to end	Day	5% 8% 3 6% 5% 4 4 3 6% 7% 51%	1799
December	1st to 10th	Day	3 10% 3 7% 4 4 5% 4 4 7% 49%	2700
	11th to 20th	Day	3 5% 2 5% 4 3 5% 4 6% 9% 53%	3106
	21st to end	Day	7% 13% 4 6% 4 4 4 3 4 6% 47%	4092
January	1st to 10th	Night	5% 11% 5% 12% 6% 5% 4 3 5% 6% 41%	6467
	11th to 20th	Night	3 10% 3 11% 6% 5% 5% 4 5% 6% 43%	6480
	21st to end	Night	2 5% 4 7% 4 4 4 3 5% 7% 55%	7128
February	1st to 10th	Night	9% 12% 4 8% 6% 4 5% 4 4 6% 39%	2621
	11th to 20th	Night	6% 10% 3 9% 6% 4 4 4 6% 7% 42%	2338
	21st to end	Night	5% 8% 3 7% 5% 4 4 3 5% 6% 49%	1980
March	1st to 10th	Night	8% 9% 3 6% 4 3 4 3 5% 6% 49%	5374
	11th to 20th	Night	5% 6% 2 5% 3 4 4 4 6% 9% 51%	5284
	21st to end	Night	10% 10% 4 9% 5% 5% 5% 4 7% 9% 33%	5059
April	1st to 10th	Night	13% 9% 3 5% 4 3 4 4 5% 6% 43%	2000
	11th to 20th	Night	14% 8% 2 5% 4 4 4 4 6% 7% 42%	1977
	21st to end	Night	15% 8% 2 5% 4 4 5% 3 6% 8% 40%	1810
May	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 6% 7% 46%	4080
	11th to 20th	Night	12% 4 1 4 3 3 3 4 6% 9% 51%	3716
	21st to end	Night	19% 6% 2 5% 4 4 3 3 5% 6% 43%	3972
June	1st to 10th	Night	9% 4 2 6% 3 3 4 4 7% 9% 50%	1600
	11th to 20th	Night	12% 4 1 4 4 4 3 4 7% 8% 48%	1600
	21st to end	Night	5% 4 2 4 4 4 4 5% 8% 8% 53%	1600
July	1st to 10th	Night	5% 3 1 4 3 4 5% 4 6% 8% 57%	3640
	11th to 20th	Night	6% 4 1 4 3 4 4 4 6% 8% 55%	3640
	21st to end	Night	5% 4 2 6% 4 5% 5% 3 6% 8% 52%	3970
August	1st to 10th	Night	6% 4 2 6% 5% 4 6% 4 9% 11% 45%	3703
	11th to 20th	Night	4 5% 1 5% 4 4 5% 3 7% 9% 53%	4184
	21st to end	Night	7% 5% 2 7% 5% 5% 5% 4 6% 7% 46%	4993
September	1st to 10th	Night	7% 4 1 4 3 2 3 3 5% 5% 62%	2000
	11th to 20th	Night	7% 4 1 4 3 4 4 3 5% 6% 60%	2140
	21st to end	Night	9% 5% 1 4 3 3 3 2 5% 5% 61%	2200
October	1st to 10th	Night	8% 3 1 3 2 2 2 2 3 4 71%	3614
	11th to 20th	Night	8% 4 1 4 3 3 3 3 6% 7% 59%	4010
	21st to end	Night	10% 7% 2 5% 3 3 3 3 6% 8% 49%	4610
November	1st to 10th	Night	8% 6% 2 5% 4 3 4 4 5% 7% 51%	2665
	11th to 20th	Night	6% 7% 2 6% 5% 5% 4 4 5% 7% 49%	2730
	21st to end	Night	5% 7% 2 5% 4 4 4 4 6% 7% 51%	2819
December	1st to 10th	Night	3 6% 3 7% 5% 4 4 4 6% 7% 51%	4710
	11th to 20th	Night	4 8% 3 7% 4 4 5% 4 6% 8% 46%	5321
	21st to end	Night	6% 10% 4 8% 4 4 4 4 6% 7% 43%	7128

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	41% 7% 14% 27% 10% 1	3719
	11th to 20th	Day	41% 6% 15% 22% 15% 2	3720
	21st to end	Day	29% 6% 16% 31% 14% 5%	4092
February	1st to 10th	Day	46% 7% 12% 20% 13% 2	1795
	11th to 20th	Day	40% 8% 14% 20% 14% 4	1959
	21st to end	Day	32% 8% 15% 28% 14% 3	1650
March	1st to 10th	Day	31% 4 8% 28% 24% 4	4500
	11th to 20th	Day	26% 6% 13% 34% 20% 2	4689
	21st to end	Day	47% 7% 16% 22% 9% 1	5875
April	1st to 10th	Day	39% 6% 15% 27% 10% 3	2400
	11th to 20th	Day	42% 7% 13% 20% 15% 3	2374
	21st to end	Day	40% 7% 14% 28% 10% 1	2590
May	1st to 10th	Day	33% 7% 12% 27% 19% 2	5900
	11th to 20th	Day	37% 7% 14% 24% 15% 2	6187
	21st to end	Day	37% 8% 14% 26% 13% 2	6926
June	1st to 10th	Day	27% 9% 19% 27% 15% 2	2800
	11th to 20th	Day	27% 8% 18% 26% 16% 5%	2800
	21st to end	Day	20% 6% 13% 31% 23% 7%	2800
July	1st to 10th	Day	26% 6% 10% 30% 26% 3	6271
	11th to 20th	Day	24% 5% 11% 29% 24% 6%	6265
	21st to end	Day	25% 5% 11% 23% 24% 12%	6705
August	1st to 10th	Day	27% 6% 16% 25% 21% 6%	4446
	11th to 20th	Day	26% 7% 14% 29% 19% 5%	4090
	21st to end	Day	22% 4 11% 24% 26% 13%	4311
September	1st to 10th	Day	21% 4 9% 29% 27% 11%	2400
	11th to 20th	Day	23% 5% 10% 29% 24% 9%	2260
	21st to end	Day	23% 4 8% 31% 28% 5%	2200
October	1st to 10th	Day	20% 3 8% 19% 32% 17%	3563
	11th to 20th	Day	26% 3 13% 35% 20% 3	3105
	21st to end	Day	34% 5% 12% 30% 16% 4	3190
November	1st to 10th	Day	28% 6% 16% 27% 19% 5%	1853
	11th to 20th	Day	29% 7% 12% 27% 21% 5%	1890
	21st to end	Day	31% 5% 15% 32% 14% 3	1799
December	1st to 10th	Day	35% 4 17% 28% 15% 1	2700
	11th to 20th	Day	27% 6% 21% 31% 15% 1	3104
	21st to end	Day	39% 4 8% 35% 12% 1	4092
January	1st to 10th	Night	44% 6% 11% 24% 13% 2	6467
	11th to 20th	Night	41% 7% 12% 22% 17% 1	6480
	21st to end	Night	29% 5% 16% 30% 19% 2	7128
February	1st to 10th	Night	45% 7% 15% 20% 12% 2	2621
	11th to 20th	Night	40% 7% 14% 24% 12% 3	2338
	21st to end	Night	35% 6% 15% 26% 15% 4	1980
March	1st to 10th	Night	34% 6% 9% 27% 21% 3	5374
	11th to 20th	Night	27% 6% 15% 26% 24% 2	5284
	21st to end	Night	45% 8% 16% 21% 9% 1	5059
April	1st to 10th	Night	40% 8% 14% 23% 13% 2	2000
	11th to 20th	Night	39% 9% 13% 21% 16% 3	1977
	21st to end	Night	39% 9% 14% 24% 13% 1	1810
May	1st to 10th	Night	32% 9% 11% 26% 19% 2	4080
	11th to 20th	Night	29% 7% 16% 32% 14% 2	3717
	21st to end	Night	40% 8% 12% 24% 15% 1	3972
June	1st to 10th	Night	29% 8% 20% 26% 16% 2	1600
	11th to 20th	Night	32% 8% 19% 23% 15% 3	1600
	21st to end	Night	24% 9% 15% 28% 19% 5%	1600
July	1st to 10th	Night	23% 6% 14% 28% 25% 3	3600
	11th to 20th	Night	27% 5% 14% 28% 20% 6%	3592
	21st to end	Night	29% 6% 14% 22% 22% 6%	3856
August	1st to 10th	Night	32% 7% 17% 22% 17% 5%	2690
	11th to 20th	Night	30% 6% 17% 24% 19% 4	3032
	21st to end	Night	26% 6% 13% 20% 25% 9%	3597
September	1st to 10th	Night	23% 4 9% 28% 27% 9%	2000
	11th to 20th	Night	24% 5% 14% 25% 26% 7%	2140
	21st to end	Night	26% 4 8% 28% 25% 9%	2200
October	1st to 10th	Night	19% 4 6% 20% 31% 21%	3614
	11th to 20th	Night	25% 4 11% 34% 22% 4	4010
	21st to end	Night	32% 4 11% 28% 18% 6%	4610
November	1st to 10th	Night	31% 5% 14% 25% 19% 5%	2665
	11th to 20th	Night	32% 6% 12% 26% 18% 5%	2730
	21st to end	Night	29% 6% 15% 28% 19% 3	2819
December	1st to 10th	Night	32% 4 17% 28% 17% 2	4710
	11th to 20th	Night	35% 5% 15% 32% 11% 2	5322
	21st to end	Night	40% 5% 10% 31% 13% 1	7128

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% 9% 41% 26% 13% 4	330
	11th to 20th	Day	12% 13% 37% 32% 5%	330
	21st to end	Day	10% 11% 46% 26% 6% 1	363
February	1st to 10th	Day	11% 12% 45% 29% 3	300
	11th to 20th	Day	11% 11% 45% 27% 4 1	300
	21st to end	Day	7% 15% 47% 25% 4 1	249
March	1st to 10th	Day	10% 13% 38% 28% 10% 1	300
	11th to 20th	Day	10% 10% 36% 30% 12% 1	300
	21st to end	Day	17% 14% 32% 24% 11% 2	508
April	1st to 10th	Day	17% 16% 35% 26% 6% 1	500
	11th to 20th	Day	18% 15% 37% 24% 5%	492
	21st to end	Day	20% 10% 26% 33% 10% 1	690
May	1st to 10th	Day	15% 10% 27% 30% 14% 3	703
	11th to 20th	Day	21% 7% 24% 29% 16% 4	725
	21st to end	Day	15% 9% 28% 32% 14% 3	789
June	1st to 10th	Day	7% 6% 26% 33% 20% 8%	730
	11th to 20th	Day	10% 7% 31% 35% 14% 4	730
	21st to end	Day	7% 7% 27% 35% 21% 3	730
July	1st to 10th	Day	6% 2 24% 39% 24% 5%	721
	11th to 20th	Day	6% 3 24% 44% 19% 4	718
	21st to end	Day	6% 3 22% 40% 26% 3	794
August	1st to 10th	Day	6% 3 22% 42% 23% 4	726
	11th to 20th	Day	5% 4 20% 41% 24% 6%	647
	21st to end	Day	4 5% 22% 35% 26% 7%	583
September	1st to 10th	Day	6% 6% 23% 34% 26% 5%	530
	11th to 20th	Day	11% 3 22% 31% 25% 8%	390
	21st to end	Day	10% 10% 26% 30% 17% 6%	330
October	1st to 10th	Day	16% 7% 26% 27% 15% 10%	330
	11th to 20th	Day	12% 13% 36% 25% 11% 2	330
	21st to end	Day	12% 13% 37% 25% 11% 2	363
November	1st to 10th	Day	10% 11% 41% 25% 12% 2	330
	11th to 20th	Day	10% 13% 39% 27% 9% 1	330
	21st to end	Day	10% 8% 34% 35% 12% 1	330
December	1st to 10th	Day	8% 13% 45% 25% 8% 1	330
	11th to 20th	Day	10% 10% 49% 26% 4 1	330
	21st to end	Day	13% 13% 41% 25% 7% 1	363
January	1st to 10th	Night	8% 9% 41% 31% 9% 1	1050
	11th to 20th	Night	9% 12% 43% 31% 6%	1050
	21st to end	Night	10% 9% 44% 32% 6%	1155
February	1st to 10th	Night	14% 10% 46% 25% 5%	871
	11th to 20th	Night	11% 7% 46% 31% 5%	784
	21st to end	Night	10% 8% 48% 29% 6%	660
March	1st to 10th	Night	12% 9% 38% 36% 5%	800
	11th to 20th	Night	10% 7% 42% 33% 7% 1	735
	21st to end	Night	15% 10% 35% 32% 8%	660
April	1st to 10th	Night	16% 10% 39% 32% 3	600
	11th to 20th	Night	17% 11% 39% 30% 3	593
	21st to end	Night	17% 11% 32% 32% 8%	600
May	1st to 10th	Night	15% 8% 31% 34% 12% 1	600
	11th to 20th	Night	18% 7% 29% 34% 12% 1	591
	21st to end	Night	17% 8% 35% 32% 8%	650
June	1st to 10th	Night	9% 5% 32% 40% 13% 1	600
	11th to 20th	Night	12% 6% 40% 35% 8%	600
	21st to end	Night	6% 4 36% 45% 10%	600
July	1st to 10th	Night	5% 2 30% 45% 18% 1	585
	11th to 20th	Night	5% 3 32% 50% 10%	582
	21st to end	Night	4 2 32% 49% 12%	657
August	1st to 10th	Night	4 4 29% 51% 12%	597
	11th to 20th	Night	4 4 29% 47% 15% 1	594
	21st to end	Night	5% 3 31% 49% 12%	660
September	1st to 10th	Night	8% 3 30% 48% 12% 1	600
	11th to 20th	Night	9% 5% 31% 41% 14% 1	600
	21st to end	Night	12% 5% 33% 39% 11% 1	600
October	1st to 10th	Night	16% 6% 28% 37% 12%	611
	11th to 20th	Night	12% 7% 37% 35% 10%	861
	21st to end	Night	13% 7% 36% 33% 10% 1	1100
November	1st to 10th	Night	10% 7% 42% 34% 6% 1	1025
	11th to 20th	Night	9% 8% 44% 33% 6%	1050
	21st to end	Night	8% 7% 41% 37% 7%	1050
December	1st to 10th	Night	9% 9% 48% 29% 5%	1050
	11th to 20th	Night	8% 8% 48% 31% 6%	1050
	21st to end	Night	13% 11% 43% 27% 6%	1155

Page generated at 2026-01-29 00:21:45. Version ac07

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