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 2024-01-14.

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 4 4 3 4 4 5% 8% 51%	74839
	Night	8% 7% 3 5% 5% 3 4 5% 5% 7% 49%	74953
Transparency	Day	31% 7% 15% 27% 17% 4	74543
	Night	33% 7% 14% 26% 17% 4	74771
Seeing	Day	10% 8% 30% 32% 16% 3	14711
	Night	11% 7% 38% 35% 9%	24809

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	4 6% 3 6% 5% 4 5% 5% 7% 8% 46%	1518
	11th to 20th	Day	6% 7% 4 6% 6% 3 6% 5% 5% 8% 45%	1464
	21st to end	Day	6% 9% 4 8% 5% 3 5% 5% 6% 8% 41%	1584
February	1st to 10th	Day	7% 11% 5% 9% 7% 4 5% 4 4 7% 38%	1615
	11th to 20th	Day	8% 9% 4 6% 6% 3 5% 6% 5% 7% 42%	1749
	21st to end	Day	6% 9% 4 7% 4 3 5% 5% 5% 8% 44%	1480
March	1st to 10th	Day	7% 9% 3 5% 5% 3 3 4 5% 7% 50%	1800
	11th to 20th	Day	8% 6% 2 5% 4 3 5% 5% 5% 8% 48%	1858
	21st to end	Day	11% 9% 4 7% 5% 3 5% 5% 6% 8% 37%	2338
April	1st to 10th	Day	12% 9% 3 5% 5% 2 4 4 4 8% 44%	2160
	11th to 20th	Day	15% 9% 3 6% 4 3 4 4 5% 7% 39%	2131
	21st to end	Day	14% 8% 3 4 5% 2 4 4 5% 7% 43%	2330
May	1st to 10th	Day	13% 6% 3 6% 4 3 4 4 5% 8% 45%	2340
	11th to 20th	Day	16% 8% 2 4 4 3 4 5% 5% 8% 41%	2428
	21st to end	Day	15% 6% 2 4 4 3 5% 5% 6% 8% 43%	2724
June	1st to 10th	Day	9% 4 1 3 4 3 4 6% 6% 10% 51%	2520
	11th to 20th	Day	9% 4 2 3 3 2 5% 5% 7% 9% 53%	2520
	21st to end	Day	4 3 1 4 3 2 4 4 6% 8% 61%	2520
July	1st to 10th	Day	5% 3 2 3 4 3 5% 6% 6% 10% 54%	2520
	11th to 20th	Day	5% 2 2 2 3 2 2 4 5% 9% 65%	2520
	21st to end	Day	5% 3 2 3 4 2 4 4 6% 9% 57%	2742
August	1st to 10th	Day	5% 4 2 4 4 3 4 5% 7% 10% 52%	2459
	11th to 20th	Day	5% 3 2 3 3 2 3 5% 4 7% 63%	2241
	21st to end	Day	6% 3 1 4 4 3 3 4 5% 6% 62%	2376
September	1st to 10th	Day	6% 3 2 3 3 2 3 4 4 6% 64%	2160
	11th to 20th	Day	8% 3 1 3 3 2 3 3 4 5% 64%	2034
	21st to end	Day	10% 4 1 3 3 2 3 3 3 6% 61%	1980
October	1st to 10th	Day	13% 7% 2 4 3 2 3 4 4 6% 53%	1967
	11th to 20th	Day	11% 5% 2 4 3 2 3 3 4 9% 55%	1727
	21st to end	Day	9% 7% 2 3 4 2 3 4 4 7% 53%	1782
November	1st to 10th	Day	7% 5% 2 4 3 3 5% 5% 6% 8% 52%	1673
	11th to 20th	Day	6% 7% 3 5% 5% 2 4 5% 5% 8% 51%	1710
	21st to end	Day	5% 8% 3 5% 4 3 4 4 5% 7% 52%	1629
December	1st to 10th	Day	5% 8% 2 6% 4 3 4 5% 5% 8% 48%	1520
	11th to 20th	Day	4 6% 3 5% 4 2 3 5% 5% 9% 54%	1926
	21st to end	Day	8% 14% 4 5% 5% 3 4 4 4 6% 44%	2794
January	1st to 10th	Night	4 7% 3 8% 6% 3 5% 5% 5% 8% 46%	2647
	11th to 20th	Night	5% 8% 3 7% 6% 3 5% 6% 6% 8% 44%	2575
	21st to end	Night	6% 10% 4 8% 6% 3 4 4 5% 8% 40%	2772
February	1st to 10th	Night	9% 11% 4 7% 6% 3 4 4 4 6% 40%	2358
	11th to 20th	Night	7% 9% 3 7% 7% 3 4 4 6% 7% 43%	2098
	21st to end	Night	6% 9% 4 6% 6% 3 5% 4 5% 6% 47%	1776
March	1st to 10th	Night	8% 7% 3 6% 5% 3 5% 5% 6% 7% 46%	2160
	11th to 20th	Night	9% 6% 3 4 4 4 5% 5% 6% 9% 45%	2102
	21st to end	Night	12% 9% 4 5% 5% 3 4 5% 6% 8% 40%	2016
April	1st to 10th	Night	13% 8% 4 5% 4 2 4 5% 5% 7% 43%	1800
	11th to 20th	Night	15% 8% 2 5% 5% 3 4 5% 6% 6% 41%	1777
	21st to end	Night	15% 6% 2 4 5% 3 5% 4 6% 8% 41%	1630
May	1st to 10th	Night	13% 7% 2 5% 5% 3 5% 5% 5% 7% 42%	1620
	11th to 20th	Night	16% 6% 2 5% 4 2 4 5% 5% 9% 42%	1464
	21st to end	Night	13% 5% 2 4 5% 3 5% 5% 6% 8% 44%	1552
June	1st to 10th	Night	9% 4 2 5% 4 3 4 5% 7% 10% 50%	1440
	11th to 20th	Night	12% 3 1 4 5% 3 4 5% 6% 8% 49%	1440
	21st to end	Night	4 3 2 3 4 3 4 6% 8% 8% 54%	1440
July	1st to 10th	Night	4 4 1 4 5% 2 6% 5% 7% 9% 54%	1440
	11th to 20th	Night	4 3 1 3 3 2 4 4 5% 6% 65%	1440
	21st to end	Night	4 2 2 4 5% 3 5% 5% 6% 9% 55%	1576
August	1st to 10th	Night	4 4 1 4 4 3 6% 6% 8% 11% 48%	1480
	11th to 20th	Night	4 3 1 3 3 2 4 4 5% 8% 62%	1658
	21st to end	Night	4 3 2 3 3 2 5% 5% 5% 6% 62%	1980
September	1st to 10th	Night	7% 5% 2 3 3 2 3 4 5% 5% 61%	1800
	11th to 20th	Night	7% 4 1 3 3 2 4 3 5% 6% 63%	1926
	21st to end	Night	9% 4 2 4 3 2 3 3 4 6% 59%	1980
October	1st to 10th	Night	14% 5% 2 4 4 2 3 4 5% 6% 50%	1989
	11th to 20th	Night	10% 4 2 4 3 3 3 4 5% 5% 56%	2214
	21st to end	Night	11% 6% 2 4 4 3 3 4 5% 8% 51%	2574
November	1st to 10th	Night	8% 6% 2 4 5% 3 4 5% 5% 8% 51%	2405
	11th to 20th	Night	6% 7% 3 5% 5% 3 5% 5% 5% 7% 48%	2470
	21st to end	Night	5% 7% 3 4 4 3 4 5% 6% 8% 52%	2550
December	1st to 10th	Night	5% 7% 4 6% 5% 3 4 4 6% 7% 48%	2660
	11th to 20th	Night	4 6% 3 6% 4 3 5% 5% 6% 8% 50%	3271
	21st to end	Night	7% 12% 4 6% 4 3 4 4 5% 7% 44%	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% 17% 27% 13% 1	1519
	11th to 20th	Day	36% 6% 21% 24% 11% 1	1464
	21st to end	Day	39% 8% 19% 22% 11% 2	1584
February	1st to 10th	Day	46% 8% 13% 20% 11% 2	1615
	11th to 20th	Day	40% 8% 15% 20% 13% 4	1759
	21st to end	Day	35% 8% 15% 27% 12% 3	1480
March	1st to 10th	Day	34% 5% 16% 28% 14% 3	1800
	11th to 20th	Day	32% 7% 15% 29% 15% 2	1858
	21st to end	Day	42% 8% 16% 23% 10% 1	2338
April	1st to 10th	Day	39% 7% 16% 26% 10% 3	2160
	11th to 20th	Day	43% 7% 14% 21% 13% 2	2134
	21st to end	Day	40% 7% 14% 28% 10% 1	2330
May	1st to 10th	Day	37% 8% 16% 28% 10% 1	2340
	11th to 20th	Day	40% 8% 19% 24% 9% 1	2432
	21st to end	Day	37% 9% 19% 23% 11% 1	2724
June	1st to 10th	Day	27% 9% 19% 28% 15% 2	2520
	11th to 20th	Day	26% 8% 18% 27% 16% 5%	2520
	21st to end	Day	19% 7% 14% 31% 23% 7%	2520
July	1st to 10th	Day	23% 8% 15% 26% 23% 5%	2451
	11th to 20th	Day	17% 6% 11% 28% 26% 12%	2445
	21st to end	Day	22% 7% 14% 26% 22% 10%	2590
August	1st to 10th	Day	25% 8% 16% 28% 18% 5%	2443
	11th to 20th	Day	20% 6% 12% 34% 19% 8%	2241
	21st to end	Day	23% 5% 10% 24% 28% 11%	2376
September	1st to 10th	Day	21% 5% 9% 27% 26% 12%	2160
	11th to 20th	Day	22% 6% 10% 29% 24% 9%	2034
	21st to end	Day	25% 5% 8% 32% 27% 4	1980
October	1st to 10th	Day	33% 5% 11% 23% 24% 4	1967
	11th to 20th	Day	28% 4 12% 31% 20% 5%	1727
	21st to end	Day	30% 6% 16% 28% 16% 4	1782
November	1st to 10th	Day	28% 6% 16% 27% 19% 5%	1673
	11th to 20th	Day	29% 7% 12% 27% 20% 5%	1710
	21st to end	Day	30% 5% 15% 31% 15% 4	1629
December	1st to 10th	Day	33% 6% 16% 28% 16% 2	1520
	11th to 20th	Day	26% 6% 21% 34% 12% 1	1924
	21st to end	Day	41% 6% 10% 29% 13% 1	2794
January	1st to 10th	Night	35% 7% 17% 25% 14% 2	2647
	11th to 20th	Night	36% 8% 16% 24% 15% 1	2575
	21st to end	Night	41% 7% 16% 23% 12% 2	2772
February	1st to 10th	Night	44% 6% 16% 21% 11% 2	2358
	11th to 20th	Night	39% 7% 14% 25% 12% 3	2098
	21st to end	Night	38% 6% 15% 24% 13% 4	1776
March	1st to 10th	Night	36% 6% 15% 27% 15% 1	2160
	11th to 20th	Night	34% 7% 14% 24% 18% 3	2102
	21st to end	Night	41% 7% 16% 24% 12% 1	2016
April	1st to 10th	Night	40% 8% 13% 23% 13% 2	1800
	11th to 20th	Night	41% 9% 13% 20% 14% 3	1777
	21st to end	Night	39% 9% 14% 24% 14% 1	1630
May	1st to 10th	Night	40% 8% 14% 26% 11% 1	1620
	11th to 20th	Night	38% 9% 18% 28% 7%	1465
	21st to end	Night	37% 9% 18% 21% 13% 1	1552
June	1st to 10th	Night	30% 7% 20% 27% 15% 2	1440
	11th to 20th	Night	31% 8% 19% 24% 15% 3	1440
	21st to end	Night	23% 10% 16% 29% 19% 5%	1440
July	1st to 10th	Night	24% 9% 15% 26% 21% 5%	1400
	11th to 20th	Night	19% 7% 13% 24% 23% 14%	1392
	21st to end	Night	24% 7% 13% 27% 21% 8%	1488
August	1st to 10th	Night	25% 9% 16% 27% 16% 5%	1472
	11th to 20th	Night	20% 6% 13% 29% 26% 6%	1658
	21st to end	Night	21% 7% 11% 25% 26% 11%	1980
September	1st to 10th	Night	24% 4 9% 27% 26% 9%	1800
	11th to 20th	Night	21% 5% 14% 26% 27% 7%	1926
	21st to end	Night	27% 4 9% 28% 25% 7%	1980
October	1st to 10th	Night	34% 6% 10% 24% 20% 6%	1989
	11th to 20th	Night	28% 6% 11% 27% 21% 7%	2214
	21st to end	Night	31% 6% 14% 24% 18% 7%	2574
November	1st to 10th	Night	30% 6% 15% 24% 19% 6%	2405
	11th to 20th	Night	33% 6% 12% 25% 18% 5%	2470
	21st to end	Night	29% 6% 15% 27% 20% 3	2550
December	1st to 10th	Night	34% 6% 15% 26% 17% 3	2660
	11th to 20th	Night	30% 6% 15% 35% 12% 2	3272
	21st to end	Night	39% 7% 12% 29% 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	4 7% 42% 27% 15% 4	270
	11th to 20th	Day	13% 12% 32% 35% 7%	249
	21st to end	Day	11% 12% 47% 25% 4 1	264
February	1st to 10th	Day	10% 11% 47% 30% 2	240
	11th to 20th	Day	13% 11% 45% 26% 4 1	240
	21st to end	Day	8% 13% 49% 23% 5% 2	198
March	1st to 10th	Day	9% 13% 40% 28% 9% 1	240
	11th to 20th	Day	11% 8% 36% 31% 13% 1	240
	21st to end	Day	16% 12% 32% 25% 12% 2	424
April	1st to 10th	Day	15% 16% 35% 27% 6%	420
	11th to 20th	Day	19% 15% 38% 23% 5%	412
	21st to end	Day	19% 10% 25% 34% 11% 1	590
May	1st to 10th	Day	15% 9% 27% 30% 15% 3	603
	11th to 20th	Day	21% 7% 23% 30% 16% 4	625
	21st to end	Day	15% 8% 27% 32% 14% 4	679
June	1st to 10th	Day	7% 5% 25% 33% 21% 9%	630
	11th to 20th	Day	11% 6% 31% 34% 14% 4	630
	21st to end	Day	6% 6% 27% 36% 22% 3	630
July	1st to 10th	Day	5% 2 24% 40% 25% 5%	621
	11th to 20th	Day	6% 3 24% 45% 18% 4	618
	21st to end	Day	5% 3 21% 40% 27% 3	684
August	1st to 10th	Day	6% 3 22% 42% 24% 4	626
	11th to 20th	Day	5% 4 19% 41% 24% 6%	555
	21st to end	Day	4 6% 21% 35% 27% 7%	495
September	1st to 10th	Day	6% 6% 24% 35% 25% 4	450
	11th to 20th	Day	8% 2 23% 31% 27% 9%	324
	21st to end	Day	12% 11% 28% 30% 16% 4	270
October	1st to 10th	Day	17% 7% 26% 27% 14% 9%	270
	11th to 20th	Day	13% 13% 34% 24% 13% 3	270
	21st to end	Day	11% 12% 38% 26% 10% 2	297
November	1st to 10th	Day	10% 10% 39% 26% 14% 2	270
	11th to 20th	Day	11% 11% 38% 30% 9% 1	270
	21st to end	Day	10% 9% 37% 32% 11%	270
December	1st to 10th	Day	9% 14% 43% 25% 9% 1	270
	11th to 20th	Day	9% 10% 49% 27% 5% 1	270
	21st to end	Day	14% 12% 40% 26% 7% 1	297
January	1st to 10th	Night	8% 10% 41% 31% 9% 1	950
	11th to 20th	Night	8% 11% 43% 31% 7%	920
	21st to end	Night	11% 9% 44% 31% 5%	990
February	1st to 10th	Night	14% 9% 47% 25% 5%	783
	11th to 20th	Night	11% 7% 47% 29% 5%	704
	21st to end	Night	11% 8% 47% 28% 6% 1	592
March	1st to 10th	Night	11% 8% 39% 36% 5%	720
	11th to 20th	Night	10% 7% 41% 34% 7% 1	662
	21st to end	Night	14% 10% 35% 32% 9%	594
April	1st to 10th	Night	15% 10% 40% 32% 3	540
	11th to 20th	Night	18% 10% 39% 30% 3	533
	21st to end	Night	16% 10% 31% 32% 9%	540
May	1st to 10th	Night	15% 7% 31% 33% 12% 1	540
	11th to 20th	Night	19% 6% 28% 33% 13% 1	531
	21st to end	Night	16% 8% 36% 32% 9%	584
June	1st to 10th	Night	10% 5% 31% 40% 14% 1	540
	11th to 20th	Night	12% 5% 39% 36% 9%	540
	21st to end	Night	5% 3 34% 47% 11%	540
July	1st to 10th	Night	5% 2 30% 44% 18% 1	525
	11th to 20th	Night	5% 3 33% 50% 10%	522
	21st to end	Night	4 2 30% 51% 13%	591
August	1st to 10th	Night	4 3 27% 52% 13%	537
	11th to 20th	Night	4 3 28% 49% 16% 1	534
	21st to end	Night	4 3 31% 48% 13%	594
September	1st to 10th	Night	9% 3 30% 47% 11% 1	540
	11th to 20th	Night	8% 4 30% 42% 14% 1	540
	21st to end	Night	12% 4 34% 38% 11% 1	540
October	1st to 10th	Night	17% 7% 28% 36% 12%	549
	11th to 20th	Night	12% 6% 36% 35% 10%	774
	21st to end	Night	14% 7% 35% 34% 10% 1	990
November	1st to 10th	Night	10% 7% 41% 35% 7% 1	925
	11th to 20th	Night	9% 8% 43% 33% 7%	950
	21st to end	Night	9% 7% 41% 36% 7%	950
December	1st to 10th	Night	9% 9% 48% 29% 5%	950
	11th to 20th	Night	7% 7% 47% 32% 6%	950
	21st to end	Night	14% 11% 42% 27% 6%	1045

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