Yankton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Yankton clear sky chart from 2005-11-06 to 2024-10-24.

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	11% 7% 3 7% 4 4 4 3 5% 7% 44%	101171
	Night	10% 7% 3 7% 4 4 4 3 5% 7% 46%	97672
Transparency	Day	22% 48% 7% 14% 7% 1	100973
	Night	20% 49% 8% 14% 8% 1	97541
Seeing	Day	14% 9% 30% 30% 14% 3	15866
	Night	13% 9% 33% 35% 10% 1	25712

By Month

Percentage Cloud Cover SE (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% 12% 4 12% 7% 6% 6% 4 6% 5% 28%	2538
	11th to 20th	Day	6% 13% 6% 10% 6% 5% 7% 4 7% 7% 29%	2630
	21st to end	Day	6% 12% 5% 13% 6% 5% 6% 4 5% 6% 32%	3135
February	1st to 10th	Day	10% 10% 4 10% 8% 6% 6% 5% 6% 6% 30%	1710
	11th to 20th	Day	10% 11% 3 9% 5% 4 4 3 5% 7% 39%	1731
	21st to end	Day	11% 10% 4 9% 7% 4 5% 3 5% 8% 35%	1570
March	1st to 10th	Day	10% 8% 4 8% 4 3 4 3 3 6% 46%	3275
	11th to 20th	Day	10% 8% 3 6% 4 4 4 3 4 6% 48%	3480
	21st to end	Day	24% 11% 4 11% 4 5% 3 3 4 5% 24%	3814
April	1st to 10th	Day	15% 8% 3 7% 4 4 4 4 5% 6% 41%	2148
	11th to 20th	Day	18% 9% 2 6% 4 4 4 4 4 6% 40%	2442
	21st to end	Day	21% 6% 3 6% 4 4 4 2 5% 6% 39%	2470
May	1st to 10th	Day	16% 6% 2 6% 5% 4 5% 4 7% 7% 37%	4082
	11th to 20th	Day	11% 6% 2 6% 4 4 4 3 5% 6% 50%	4082
	21st to end	Day	17% 6% 2 6% 4 4 3 3 5% 8% 41%	4625
June	1st to 10th	Day	10% 4 2 5% 4 3 5% 4 6% 7% 50%	2769
	11th to 20th	Day	12% 6% 2 5% 4 4 4 4 6% 8% 47%	2850
	21st to end	Day	8% 4 2 5% 3 4 4 4 7% 8% 51%	2850
July	1st to 10th	Day	10% 4 2 6% 5% 4 4 4 7% 9% 45%	4528
	11th to 20th	Day	6% 4 2 5% 3 4 3 3 5% 7% 57%	4386
	21st to end	Day	4 3 1 5% 4 3 4 4 6% 9% 57%	4465
August	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 6% 8% 49%	4104
	11th to 20th	Day	16% 7% 3 6% 4 4 4 4 6% 7% 39%	4041
	21st to end	Day	7% 5% 2 5% 4 4 3 3 5% 7% 55%	4532
September	1st to 10th	Day	14% 6% 2 4 3 3 3 3 5% 5% 54%	2177
	11th to 20th	Day	7% 5% 2 4 3 4 4 3 5% 8% 56%	2090
	21st to end	Day	10% 4 1 4 3 3 3 3 5% 7% 57%	2090
October	1st to 10th	Day	14% 5% 2 5% 3 3 3 3 4 5% 52%	1990
	11th to 20th	Day	11% 7% 2 4 3 2 3 3 5% 6% 55%	1900
	21st to end	Day	15% 7% 3 6% 3 3 4 2 4 5% 48%	1912
November	1st to 10th	Day	8% 6% 2 5% 4 3 5% 4 5% 8% 49%	1673
	11th to 20th	Day	9% 7% 2 7% 5% 5% 4 4 5% 7% 45%	1660
	21st to end	Day	10% 9% 3 7% 4 3 3 4 5% 8% 45%	1520
December	1st to 10th	Day	8% 11% 2 8% 6% 4 4 3 5% 8% 41%	1520
	11th to 20th	Day	7% 10% 4 9% 6% 4 5% 5% 5% 7% 38%	1876
	21st to end	Day	15% 10% 5% 15% 6% 5% 4 3 5% 7% 27%	2506
January	1st to 10th	Night	10% 10% 4 12% 9% 8% 5% 4 5% 7% 25%	4417
	11th to 20th	Night	5% 10% 5% 10% 5% 6% 7% 5% 9% 6% 33%	4336
	21st to end	Night	6% 11% 6% 12% 5% 5% 5% 5% 5% 7% 33%	4532
February	1st to 10th	Night	10% 10% 4 9% 6% 4 4 4 4 6% 39%	2470
	11th to 20th	Night	8% 11% 4 8% 4 3 4 3 5% 7% 43%	2351
	21st to end	Night	9% 9% 3 6% 5% 4 5% 4 5% 6% 45%	1884
March	1st to 10th	Night	10% 6% 2 6% 3 3 3 3 5% 6% 53%	3584
	11th to 20th	Night	10% 6% 2 5% 3 3 4 2 4 8% 52%	3480
	21st to end	Night	21% 10% 3 8% 5% 5% 4 4 5% 6% 30%	3817
April	1st to 10th	Night	13% 9% 2 6% 4 3 4 4 5% 7% 42%	2028
	11th to 20th	Night	16% 7% 2 6% 4 4 3 3 6% 5% 44%	1689
	21st to end	Night	17% 7% 2 5% 5% 3 4 3 5% 5% 43%	1710
May	1st to 10th	Night	17% 5% 2 5% 4 3 3 3 5% 6% 47%	2823
	11th to 20th	Night	10% 5% 2 5% 3 3 4 4 6% 7% 51%	2823
	21st to end	Night	16% 6% 2 5% 4 3 3 4 5% 8% 44%	2941
June	1st to 10th	Night	7% 6% 2 3 3 4 3 3 6% 10% 54%	1406
	11th to 20th	Night	7% 5% 1 4 3 4 3 4 7% 10% 52%	1330
	21st to end	Night	7% 3 1 4 3 2 4 3 6% 8% 58%	1330
July	1st to 10th	Night	7% 5% 2 6% 4 4 3 3 6% 8% 53%	2436
	11th to 20th	Night	5% 3 1 3 2 3 3 3 5% 7% 64%	2571
	21st to end	Night	2 2 1 4 3 3 4 4 6% 11% 61%	3098
August	1st to 10th	Night	5% 5% 2 6% 5% 4 4 3 7% 9% 50%	2836
	11th to 20th	Night	10% 5% 2 5% 3 4 4 4 6% 9% 49%	2798
	21st to end	Night	7% 3 2 6% 3 3 4 3 6% 9% 55%	3135
September	1st to 10th	Night	8% 4 1 5% 2 3 4 3 5% 6% 59%	1996
	11th to 20th	Night	8% 3 2 4 3 2 3 3 5% 7% 59%	2090
	21st to end	Night	8% 4 1 3 3 3 4 3 4 7% 61%	2090
October	1st to 10th	Night	16% 4 2 5% 3 3 3 3 4 5% 53%	2171
	11th to 20th	Night	10% 5% 2 4 3 3 4 3 5% 5% 56%	2280
	21st to end	Night	13% 6% 2 5% 3 3 3 3 4 6% 53%	2507
November	1st to 10th	Night	7% 5% 2 5% 4 3 4 3 5% 8% 55%	2405
	11th to 20th	Night	8% 6% 2 7% 4 4 5% 3 6% 6% 49%	2517
	21st to end	Night	9% 7% 2 4 3 4 4 4 6% 6% 50%	2660
December	1st to 10th	Night	8% 9% 3 8% 5% 4 5% 3 5% 7% 43%	2660
	11th to 20th	Night	8% 8% 3 8% 4 4 5% 4 5% 9% 44%	3314
	21st to end	Night	17% 12% 5% 12% 4 3 3 3 4 5% 31%	5157

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	40% 38% 7% 11% 4	2539
	11th to 20th	Day	36% 37% 8% 16% 4	2630
	21st to end	Day	30% 40% 14% 9% 7%	3135
February	1st to 10th	Day	20% 67% 5% 5% 3	1710
	11th to 20th	Day	17% 64% 4 10% 4 1	1740
	21st to end	Day	17% 64% 4 6% 8% 1	1570
March	1st to 10th	Day	22% 40% 6% 20% 11% 1	3275
	11th to 20th	Day	20% 40% 5% 21% 11% 3	3480
	21st to end	Day	42% 40% 8% 8% 1	3814
April	1st to 10th	Day	18% 65% 5% 8% 4	2148
	11th to 20th	Day	15% 66% 5% 9% 4 1	2442
	21st to end	Day	18% 65% 4 8% 5%	2470
May	1st to 10th	Day	27% 41% 7% 13% 10%	4120
	11th to 20th	Day	20% 40% 7% 18% 13% 2	4086
	21st to end	Day	26% 40% 7% 17% 10%	4638
June	1st to 10th	Day	9% 65% 6% 13% 6% 1	2769
	11th to 20th	Day	14% 66% 6% 10% 4 1	2850
	21st to end	Day	12% 65% 6% 12% 4 1	2850
July	1st to 10th	Day	25% 38% 13% 15% 8%	4459
	11th to 20th	Day	19% 37% 9% 23% 11% 1	4311
	21st to end	Day	15% 38% 12% 18% 14% 2	4325
August	1st to 10th	Day	22% 39% 9% 21% 9% 2	4090
	11th to 20th	Day	33% 40% 8% 15% 5%	4080
	21st to end	Day	21% 39% 12% 17% 10% 1	4531
September	1st to 10th	Day	14% 60% 5% 14% 6%	2177
	11th to 20th	Day	9% 61% 6% 16% 8% 1	2090
	21st to end	Day	14% 61% 3 12% 8% 1	2090
October	1st to 10th	Day	16% 60% 4 13% 6% 1	1990
	11th to 20th	Day	11% 60% 4 14% 9% 3	1900
	21st to end	Day	15% 61% 4 10% 8% 1	1912
November	1st to 10th	Day	17% 59% 7% 11% 7%	1673
	11th to 20th	Day	15% 60% 5% 12% 7% 1	1660
	21st to end	Day	19% 61% 4 9% 6% 1	1520
December	1st to 10th	Day	17% 60% 6% 11% 5% 1	1520
	11th to 20th	Day	22% 48% 10% 17% 3	1873
	21st to end	Day	38% 36% 7% 14% 4 1	2506
January	1st to 10th	Night	42% 37% 7% 10% 4	4417
	11th to 20th	Night	31% 37% 9% 15% 5% 2	4336
	21st to end	Night	29% 39% 13% 12% 6%	4532
February	1st to 10th	Night	17% 66% 6% 6% 4 1	2470
	11th to 20th	Night	17% 64% 5% 8% 4 2	2352
	21st to end	Night	13% 65% 3 9% 7% 2	1884
March	1st to 10th	Night	16% 41% 6% 14% 21% 1	3584
	11th to 20th	Night	17% 40% 6% 20% 14% 3	3480
	21st to end	Night	36% 41% 11% 9% 2	3817
April	1st to 10th	Night	15% 66% 6% 8% 4 1	2028
	11th to 20th	Night	14% 67% 4 9% 6% 1	1689
	21st to end	Night	16% 65% 5% 7% 6% 1	1710
May	1st to 10th	Night	24% 40% 8% 11% 14% 2	2850
	11th to 20th	Night	18% 40% 8% 16% 16% 2	2824
	21st to end	Night	22% 40% 7% 19% 11% 1	2949
June	1st to 10th	Night	7% 66% 6% 10% 8% 2	1406
	11th to 20th	Night	12% 66% 5% 10% 7%	1330
	21st to end	Night	9% 63% 8% 13% 6% 1	1330
July	1st to 10th	Night	21% 37% 16% 18% 7% 2	2396
	11th to 20th	Night	14% 36% 9% 28% 11% 1	2523
	21st to end	Night	11% 38% 13% 21% 14% 3	2999
August	1st to 10th	Night	20% 38% 9% 21% 10% 1	2826
	11th to 20th	Night	25% 40% 11% 17% 7% 1	2825
	21st to end	Night	19% 40% 12% 15% 13% 1	3135
September	1st to 10th	Night	11% 61% 5% 12% 10% 1	1996
	11th to 20th	Night	10% 60% 5% 16% 9% 1	2090
	21st to end	Night	12% 61% 4 11% 11% 1	2090
October	1st to 10th	Night	15% 60% 5% 12% 8%	2171
	11th to 20th	Night	9% 59% 3 14% 12% 3	2280
	21st to end	Night	13% 61% 5% 9% 10%	2507
November	1st to 10th	Night	13% 59% 7% 12% 8% 1	2405
	11th to 20th	Night	13% 60% 6% 13% 8% 1	2517
	21st to end	Night	15% 60% 6% 12% 7% 1	2660
December	1st to 10th	Night	17% 60% 6% 13% 5%	2660
	11th to 20th	Night	16% 50% 8% 20% 5%	3316
	21st to end	Night	40% 37% 7% 12% 4	5157

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	17% 12% 29% 29% 10% 3	270
	11th to 20th	Day	16% 14% 33% 29% 7% 1	270
	21st to end	Day	13% 10% 39% 26% 10% 2	297
February	1st to 10th	Day	10% 16% 41% 30% 3	270
	11th to 20th	Day	15% 13% 38% 24% 8% 1	270
	21st to end	Day	18% 13% 39% 24% 6%	225
March	1st to 10th	Day	14% 12% 42% 27% 3 1	270
	11th to 20th	Day	18% 12% 37% 22% 10% 1	270
	21st to end	Day	28% 10% 38% 18% 4 2	297
April	1st to 10th	Day	20% 19% 38% 18% 4	328
	11th to 20th	Day	24% 15% 31% 25% 6%	640
	21st to end	Day	25% 11% 31% 22% 9% 2	650
May	1st to 10th	Day	19% 13% 34% 24% 9% 1	653
	11th to 20th	Day	19% 9% 30% 24% 15% 3	675
	21st to end	Day	19% 8% 30% 28% 12% 3	734
June	1st to 10th	Day	8% 8% 23% 34% 22% 5%	680
	11th to 20th	Day	12% 7% 35% 30% 14% 2	680
	21st to end	Day	10% 8% 27% 36% 17% 2	680
July	1st to 10th	Day	6% 3 22% 36% 27% 6%	671
	11th to 20th	Day	7% 5% 24% 42% 19% 3	668
	21st to end	Day	5% 4 24% 45% 19% 4	739
August	1st to 10th	Day	9% 3 20% 42% 23% 3	676
	11th to 20th	Day	11% 4 24% 36% 21% 5%	665
	21st to end	Day	7% 4 27% 36% 23% 3	748
September	1st to 10th	Day	17% 5% 28% 30% 17% 4	387
	11th to 20th	Day	7% 5% 35% 32% 18% 3	300
	21st to end	Day	16% 10% 31% 26% 12% 5%	300
October	1st to 10th	Day	18% 9% 27% 27% 15% 4	300
	11th to 20th	Day	16% 15% 35% 23% 9% 1	300
	21st to end	Day	19% 15% 34% 24% 8% 1	306
November	1st to 10th	Day	20% 9% 34% 25% 9% 4	270
	11th to 20th	Day	13% 17% 39% 25% 6%	270
	21st to end	Day	19% 17% 30% 23% 11% 1	270
December	1st to 10th	Day	12% 11% 37% 30% 8% 2	270
	11th to 20th	Day	14% 11% 40% 25% 9%	270
	21st to end	Day	23% 11% 36% 25% 6%	297
January	1st to 10th	Night	12% 11% 35% 32% 9% 1	950
	11th to 20th	Night	12% 15% 34% 31% 7% 1	950
	21st to end	Night	13% 8% 39% 31% 8%	1045
February	1st to 10th	Night	15% 10% 39% 30% 6%	950
	11th to 20th	Night	13% 11% 38% 32% 6%	877
	21st to end	Night	15% 9% 36% 32% 8% 1	628
March	1st to 10th	Night	12% 9% 42% 30% 6% 1	675
	11th to 20th	Night	15% 11% 38% 30% 6%	570
	21st to end	Night	19% 8% 40% 25% 7%	627
April	1st to 10th	Night	17% 14% 38% 28% 3	570
	11th to 20th	Night	18% 13% 35% 26% 7%	563
	21st to end	Night	18% 10% 38% 27% 7% 1	570
May	1st to 10th	Night	15% 9% 36% 31% 8%	570
	11th to 20th	Night	16% 8% 30% 36% 11%	561
	21st to end	Night	18% 6% 31% 35% 10%	617
June	1st to 10th	Night	9% 5% 27% 41% 18% 1	570
	11th to 20th	Night	10% 4 33% 41% 12% 1	570
	21st to end	Night	7% 4 26% 47% 16%	570
July	1st to 10th	Night	6% 3 18% 45% 27% 1	555
	11th to 20th	Night	5% 2 20% 56% 17% 1	552
	21st to end	Night	5% 1 21% 56% 17% 1	624
August	1st to 10th	Night	7% 4 22% 47% 20% 1	567
	11th to 20th	Night	8% 4 23% 42% 21% 1	564
	21st to end	Night	7% 3 25% 46% 18% 1	627
September	1st to 10th	Night	9% 4 26% 43% 17% 1	570
	11th to 20th	Night	8% 5% 31% 39% 15% 2	570
	21st to end	Night	10% 6% 37% 33% 14% 1	570
October	1st to 10th	Night	18% 8% 31% 32% 10% 1	651
	11th to 20th	Night	15% 11% 37% 29% 8% 1	760
	21st to end	Night	16% 12% 32% 30% 9%	899
November	1st to 10th	Night	11% 10% 35% 34% 10% 1	925
	11th to 20th	Night	12% 11% 38% 32% 6% 1	950
	21st to end	Night	11% 11% 35% 33% 9%	950
December	1st to 10th	Night	12% 10% 39% 31% 7% 1	950
	11th to 20th	Night	13% 8% 35% 36% 8% 1	950
	21st to end	Night	21% 10% 35% 28% 6%	1045

Page generated at 2024-10-21 01:20:05. Version ac07

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