Kansas State University
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kansas State University clear sky chart from 2005-11-06 to 2024-11-25.

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	10% 7% 2 6% 4 4 4 3 5% 7% 47%	101314
	Night	10% 6% 2 6% 3 4 4 3 5% 7% 51%	98236
Transparency	Day	35% 5% 12% 26% 19% 3	105017
	Night	33% 5% 12% 26% 21% 4	102660
Seeing	Day	13% 10% 30% 29% 15% 3	15735
	Night	13% 9% 33% 34% 11% 1	25618

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	11% 10% 3 12% 5% 5% 4 3 5% 8% 34%	2847
	11th to 20th	Day	9% 11% 4 9% 4 6% 4 3 4 6% 39%	2850
	21st to end	Day	10% 14% 6% 9% 3 4 3 3 4 6% 38%	3135
February	1st to 10th	Day	12% 12% 3 8% 4 4 3 3 5% 6% 41%	1710
	11th to 20th	Day	8% 9% 3 6% 4 5% 5% 3 6% 7% 44%	1767
	21st to end	Day	8% 8% 2 8% 4 4 4 3 5% 8% 46%	1570
March	1st to 10th	Day	12% 7% 2 5% 3 3 3 3 3 7% 52%	3393
	11th to 20th	Day	11% 6% 2 4 3 3 3 3 4 6% 55%	3480
	21st to end	Day	14% 9% 4 7% 4 4 4 3 5% 6% 40%	3814
April	1st to 10th	Day	12% 7% 2 6% 4 3 3 3 5% 7% 48%	2101
	11th to 20th	Day	12% 7% 2 6% 4 5% 4 4 5% 6% 43%	2352
	21st to end	Day	17% 7% 3 5% 5% 4 5% 3 4 6% 40%	2470
May	1st to 10th	Day	15% 9% 2 7% 4 4 4 3 5% 6% 41%	4082
	11th to 20th	Day	15% 7% 3 6% 4 3 4 4 6% 6% 43%	4082
	21st to end	Day	14% 6% 2 5% 4 4 5% 4 7% 7% 42%	4477
June	1st to 10th	Day	6% 4 2 5% 4 4 4 4 5% 9% 54%	2470
	11th to 20th	Day	7% 5% 2 4 5% 4 4 4 6% 9% 51%	2470
	21st to end	Day	6% 3 2 4 4 4 5% 4 7% 9% 52%	2470
July	1st to 10th	Day	10% 6% 2 6% 4 5% 4 4 7% 8% 44%	4120
	11th to 20th	Day	6% 2 2 5% 4 5% 5% 4 8% 9% 51%	4120
	21st to end	Day	5% 3 1 4 4 4 5% 5% 7% 10% 50%	4465
August	1st to 10th	Day	7% 4 2 6% 4 4 5% 3 5% 8% 53%	4104
	11th to 20th	Day	12% 5% 2 6% 4 4 4 3 5% 7% 48%	4041
	21st to end	Day	6% 3 1 4 3 3 4 4 6% 8% 57%	4441
September	1st to 10th	Day	11% 3 2 4 3 3 3 4 5% 6% 57%	2139
	11th to 20th	Day	9% 5% 2 5% 4 4 4 3 5% 6% 53%	2090
	21st to end	Day	9% 5% 2 4 3 3 3 4 5% 6% 56%	2090
October	1st to 10th	Day	12% 5% 2 4 3 2 3 2 5% 6% 56%	1977
	11th to 20th	Day	10% 5% 2 3 3 3 3 3 3 5% 61%	1900
	21st to end	Day	12% 7% 2 5% 4 4 3 2 4 5% 53%	2090
November	1st to 10th	Day	8% 4 2 4 3 4 3 3 5% 6% 58%	1816
	11th to 20th	Day	10% 6% 2 5% 4 3 3 3 4 5% 56%	1800
	21st to end	Day	13% 7% 2 4 2 3 3 2 5% 6% 53%	1746
December	1st to 10th	Day	9% 6% 3 6% 4 3 5% 3 6% 7% 48%	1558
	11th to 20th	Day	9% 9% 3 9% 5% 4 4 3 4 7% 44%	2142
	21st to end	Day	14% 12% 6% 16% 5% 3 3 4 4 6% 27%	3135
January	1st to 10th	Night	9% 10% 3 14% 5% 4 3 3 4 5% 39%	4108
	11th to 20th	Night	8% 9% 3 7% 4 7% 5% 4 4 5% 44%	4120
	21st to end	Night	14% 14% 5% 5% 3 3 4 3 4 5% 42%	4532
February	1st to 10th	Night	10% 11% 3 7% 5% 4 4 3 5% 6% 42%	2470
	11th to 20th	Night	10% 7% 3 7% 4 4 4 4 5% 7% 45%	2315
	21st to end	Night	8% 7% 3 5% 4 4 3 4 5% 5% 52%	1884
March	1st to 10th	Night	11% 6% 2 5% 2 3 3 3 4 6% 55%	3462
	11th to 20th	Night	10% 5% 2 5% 3 3 3 3 5% 7% 54%	3480
	21st to end	Night	16% 8% 3 7% 4 3 3 3 4 6% 44%	3817
April	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 4 7% 53%	2077
	11th to 20th	Night	13% 8% 2 6% 3 4 3 3 5% 7% 46%	1776
	21st to end	Night	15% 6% 2 5% 3 4 4 3 5% 7% 45%	1710
May	1st to 10th	Night	18% 7% 2 5% 3 3 3 3 4 6% 46%	2823
	11th to 20th	Night	14% 5% 2 5% 4 4 4 4 5% 8% 46%	2823
	21st to end	Night	11% 5% 2 5% 3 4 4 4 5% 8% 51%	3090
June	1st to 10th	Night	5% 3 1 4 3 4 5% 3 7% 9% 56%	1710
	11th to 20th	Night	6% 4 1 3 3 4 4 5% 7% 9% 54%	1710
	21st to end	Night	6% 2 1 4 4 3 3 3 7% 9% 58%	1710
July	1st to 10th	Night	9% 5% 2 6% 3 4 5% 3 5% 7% 51%	2850
	11th to 20th	Night	2 3 1 4 3 4 4 4 6% 9% 60%	2850
	21st to end	Night	5% 4 2 5% 4 3 4 4 6% 10% 54%	3098
August	1st to 10th	Night	2 3 1 5% 3 4 4 4 6% 10% 56%	2836
	11th to 20th	Night	9% 6% 2 6% 4 4 4 4 4 7% 50%	2798
	21st to end	Night	5% 3 1 4 3 3 3 3 5% 7% 62%	3221
September	1st to 10th	Night	9% 3 1 4 3 4 3 3 4 6% 60%	2038
	11th to 20th	Night	9% 4 2 4 3 3 3 3 5% 6% 56%	2090
	21st to end	Night	8% 3 2 4 4 3 3 3 4 6% 61%	2090
October	1st to 10th	Night	12% 4 2 5% 3 3 4 3 5% 6% 54%	2183
	11th to 20th	Night	12% 5% 2 3 2 3 2 2 4 6% 60%	2280
	21st to end	Night	12% 6% 2 5% 3 2 2 3 4 5% 56%	2508
November	1st to 10th	Night	8% 5% 2 4 3 3 2 2 4 6% 61%	2478
	11th to 20th	Night	9% 5% 2 4 3 3 3 3 5% 5% 58%	2600
	21st to end	Night	11% 7% 2 4 3 3 3 2 4 5% 56%	2529
December	1st to 10th	Night	8% 6% 3 5% 4 3 5% 4 5% 7% 51%	2602
	11th to 20th	Night	9% 8% 3 6% 3 3 4 4 5% 6% 48%	3036
	21st to end	Night	17% 13% 6% 9% 3 3 3 3 3 4 36%	4532

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	49% 4 13% 22% 10% 1	2848
	11th to 20th	Day	47% 5% 16% 19% 12% 1	2850
	21st to end	Day	48% 4 13% 23% 12% 1	3135
February	1st to 10th	Day	45% 5% 14% 21% 11% 4	1710
	11th to 20th	Day	39% 5% 13% 27% 14% 4	1776
	21st to end	Day	36% 5% 10% 25% 20% 5%	1570
March	1st to 10th	Day	34% 3 9% 22% 26% 5%	3393
	11th to 20th	Day	31% 4 10% 29% 24% 2	3480
	21st to end	Day	44% 5% 15% 27% 7% 2	3814
April	1st to 10th	Day	36% 4 12% 23% 20% 4	2101
	11th to 20th	Day	39% 6% 11% 23% 17% 2	2352
	21st to end	Day	44% 6% 10% 26% 13%	2470
May	1st to 10th	Day	44% 6% 9% 24% 13% 3	4120
	11th to 20th	Day	41% 6% 11% 23% 19%	4086
	21st to end	Day	38% 8% 12% 27% 13% 2	4489
June	1st to 10th	Day	26% 7% 15% 34% 16% 2	2470
	11th to 20th	Day	29% 7% 13% 28% 20% 2	2470
	21st to end	Day	26% 7% 14% 29% 19% 4	2470
July	1st to 10th	Day	36% 6% 13% 22% 19% 4	4056
	11th to 20th	Day	26% 7% 12% 31% 19% 4	4051
	21st to end	Day	25% 7% 15% 30% 20% 4	4325
August	1st to 10th	Day	29% 6% 12% 25% 23% 4	4090
	11th to 20th	Day	36% 5% 14% 25% 18% 2	4080
	21st to end	Day	24% 6% 15% 28% 19% 7%	4440
September	1st to 10th	Day	28% 5% 11% 27% 21% 7%	2139
	11th to 20th	Day	31% 6% 10% 26% 24% 3	2090
	21st to end	Day	29% 6% 8% 27% 26% 4	2090
October	1st to 10th	Day	21% 3 7% 19% 43% 8%	3289
	11th to 20th	Day	18% 3 7% 30% 33% 10%	3140
	21st to end	Day	29% 3 9% 25% 30% 5%	3428
November	1st to 10th	Day	27% 5% 13% 28% 21% 6%	1816
	11th to 20th	Day	31% 4 9% 25% 27% 4	1800
	21st to end	Day	33% 4 10% 30% 20% 2	1746
December	1st to 10th	Day	35% 5% 12% 31% 16% 1	1558
	11th to 20th	Day	41% 4 12% 27% 15% 1	2140
	21st to end	Day	59% 4 9% 18% 9% 1	3135
January	1st to 10th	Night	48% 4 13% 22% 12% 1	4108
	11th to 20th	Night	42% 4 14% 22% 16% 1	4120
	21st to end	Night	46% 4 14% 20% 15% 2	4532
February	1st to 10th	Night	43% 5% 12% 22% 14% 4	2470
	11th to 20th	Night	39% 5% 10% 27% 16% 3	2316
	21st to end	Night	34% 4 9% 23% 22% 8%	1884
March	1st to 10th	Night	30% 4 8% 26% 25% 5%	3462
	11th to 20th	Night	30% 4 9% 25% 28% 4	3480
	21st to end	Night	41% 6% 16% 26% 9% 1	3817
April	1st to 10th	Night	31% 5% 13% 23% 24% 4	2077
	11th to 20th	Night	37% 5% 11% 24% 20% 3	1776
	21st to end	Night	39% 6% 11% 25% 17% 2	1710
May	1st to 10th	Night	39% 6% 12% 23% 15% 5%	2850
	11th to 20th	Night	36% 6% 13% 26% 18%	2824
	21st to end	Night	31% 8% 15% 29% 16% 1	3099
June	1st to 10th	Night	23% 9% 15% 32% 18% 3	1710
	11th to 20th	Night	24% 8% 13% 32% 18% 5%	1710
	21st to end	Night	21% 7% 13% 33% 21% 5%	1710
July	1st to 10th	Night	32% 6% 12% 23% 20% 7%	2805
	11th to 20th	Night	20% 5% 13% 30% 30% 3	2796
	21st to end	Night	25% 5% 15% 30% 22% 3	2999
August	1st to 10th	Night	22% 6% 18% 25% 22% 7%	2826
	11th to 20th	Night	34% 6% 13% 25% 20% 2	2825
	21st to end	Night	21% 5% 15% 33% 21% 5%	3221
September	1st to 10th	Night	25% 5% 10% 28% 22% 9%	2038
	11th to 20th	Night	27% 6% 10% 25% 26% 5%	2090
	21st to end	Night	26% 5% 8% 25% 31% 5%	2090
October	1st to 10th	Night	21% 3 6% 17% 45% 7%	3638
	11th to 20th	Night	19% 3 5% 29% 32% 12%	3779
	21st to end	Night	27% 3 8% 28% 30% 4	4120
November	1st to 10th	Night	26% 4 11% 28% 25% 7%	2478
	11th to 20th	Night	28% 4 10% 29% 25% 5%	2600
	21st to end	Night	32% 4 10% 29% 22% 4	2529
December	1st to 10th	Night	33% 5% 13% 28% 19% 1	2602
	11th to 20th	Night	36% 4 10% 31% 18% 1	3037
	21st to end	Night	53% 4 10% 22% 9% 2	4532

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	15% 17% 37% 21% 10%	270
	11th to 20th	Day	22% 17% 39% 19% 3	270
	21st to end	Day	14% 11% 47% 23% 4	297
February	1st to 10th	Day	19% 19% 43% 15% 4	270
	11th to 20th	Day	15% 13% 49% 16% 7%	270
	21st to end	Day	16% 18% 50% 13% 3	225
March	1st to 10th	Day	15% 20% 40% 20% 5%	270
	11th to 20th	Day	27% 12% 38% 17% 5%	270
	21st to end	Day	26% 19% 40% 13% 2 1	297
April	1st to 10th	Day	21% 19% 37% 19% 5%	281
	11th to 20th	Day	17% 17% 37% 22% 6%	550
	21st to end	Day	22% 18% 32% 20% 7% 2	650
May	1st to 10th	Day	19% 15% 36% 21% 9% 1	653
	11th to 20th	Day	19% 12% 26% 26% 15% 2	675
	21st to end	Day	16% 11% 30% 26% 14% 3	734
June	1st to 10th	Day	6% 5% 26% 35% 21% 7%	680
	11th to 20th	Day	7% 4 34% 34% 18% 3	680
	21st to end	Day	7% 8% 35% 37% 11% 2	680
July	1st to 10th	Day	10% 4 17% 34% 27% 7%	671
	11th to 20th	Day	5% 3 22% 39% 26% 6%	668
	21st to end	Day	7% 2 17% 40% 28% 5%	739
August	1st to 10th	Day	8% 3 19% 39% 29% 3	676
	11th to 20th	Day	8% 4 20% 41% 23% 4	665
	21st to end	Day	9% 2 17% 34% 29% 8%	696
September	1st to 10th	Day	11% 2 18% 40% 26% 3	349
	11th to 20th	Day	6% 5% 25% 37% 23% 4	300
	21st to end	Day	12% 8% 30% 32% 15% 3	300
October	1st to 10th	Day	15% 8% 29% 28% 14% 5%	300
	11th to 20th	Day	7% 19% 41% 22% 10% 1	300
	21st to end	Day	19% 18% 32% 24% 6% 2	330
November	1st to 10th	Day	14% 19% 32% 26% 8% 1	300
	11th to 20th	Day	17% 18% 35% 21% 8% 1	300
	21st to end	Day	21% 12% 38% 19% 9% 2	282
December	1st to 10th	Day	10% 12% 41% 26% 9% 1	270
	11th to 20th	Day	14% 17% 37% 24% 7%	270
	21st to end	Day	20% 16% 41% 21% 2	297
January	1st to 10th	Night	13% 13% 35% 32% 8%	950
	11th to 20th	Night	15% 10% 38% 29% 7% 1	950
	21st to end	Night	13% 9% 40% 32% 4	1045
February	1st to 10th	Night	17% 10% 41% 29% 3	950
	11th to 20th	Night	13% 13% 40% 31% 4	841
	21st to end	Night	14% 14% 42% 25% 5%	628
March	1st to 10th	Night	14% 12% 42% 28% 3	602
	11th to 20th	Night	16% 11% 36% 29% 6%	570
	21st to end	Night	20% 15% 38% 22% 5%	627
April	1st to 10th	Night	14% 14% 42% 25% 5%	570
	11th to 20th	Night	18% 15% 34% 28% 4 1	563
	21st to end	Night	18% 9% 39% 26% 6% 1	570
May	1st to 10th	Night	19% 9% 33% 31% 8% 1	570
	11th to 20th	Night	16% 7% 30% 35% 10% 1	561
	21st to end	Night	13% 7% 30% 34% 15% 1	617
June	1st to 10th	Night	6% 5% 25% 42% 21% 1	570
	11th to 20th	Night	7% 3 33% 39% 18%	570
	21st to end	Night	6% 4 32% 47% 11%	570
July	1st to 10th	Night	8% 1 18% 45% 27% 1	555
	11th to 20th	Night	3 1 22% 51% 21% 2	552
	21st to end	Night	7% 2 17% 47% 27% 2	624
August	1st to 10th	Night	4 2 20% 49% 24% 1	567
	11th to 20th	Night	7% 2 17% 48% 25% 1	564
	21st to end	Night	7% 2 16% 46% 27% 3	627
September	1st to 10th	Night	9% 2 25% 41% 21% 2	570
	11th to 20th	Night	10% 2 26% 40% 20% 2	570
	21st to end	Night	8% 4 26% 43% 17% 1	570
October	1st to 10th	Night	13% 6% 28% 35% 16% 2	663
	11th to 20th	Night	13% 9% 39% 31% 9%	760
	21st to end	Night	16% 12% 33% 29% 10%	836
November	1st to 10th	Night	11% 10% 32% 36% 10%	918
	11th to 20th	Night	12% 13% 38% 31% 6%	1000
	21st to end	Night	14% 12% 32% 32% 9%	973
December	1st to 10th	Night	11% 11% 36% 34% 8%	950
	11th to 20th	Night	17% 10% 37% 31% 5%	950
	21st to end	Night	18% 12% 36% 29% 4	1045

Page generated at 2024-11-22 07:02:24. Version ac07

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