Fort Hays State University
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Hays State University 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% 5% 2 5% 3 3 4 3 5% 7% 55%	137122
	Night	8% 5% 2 5% 3 3 3 3 5% 7% 55%	132241
Transparency	Day	30% 3 11% 27% 23% 6%	131937
	Night	30% 2 11% 27% 24% 7%	128433
Seeing	Day	11% 8% 32% 32% 15% 3	17266
	Night	11% 8% 35% 36% 9% 1	27292

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	9% 8% 2 7% 4 4 4 3 5% 6% 48%	4167
	11th to 20th	Day	5% 7% 3 9% 6% 4 4 2 5% 6% 49%	4170
	21st to end	Day	5% 7% 3 7% 4 3 3 3 4 5% 54%	4587
February	1st to 10th	Day	7% 10% 3 6% 4 4 4 2 5% 7% 47%	1910
	11th to 20th	Day	5% 7% 2 7% 5% 5% 5% 3 5% 6% 51%	1949
	21st to end	Day	7% 5% 1 5% 4 4 4 3 5% 5% 58%	1650
March	1st to 10th	Day	8% 6% 2 4 3 3 3 3 3 5% 61%	4557
	11th to 20th	Day	7% 6% 2 5% 3 2 3 3 4 6% 60%	4980
	21st to end	Day	8% 6% 1 4 3 4 4 4 6% 7% 53%	5464
April	1st to 10th	Day	9% 5% 2 4 3 4 4 3 5% 6% 55%	2326
	11th to 20th	Day	9% 7% 3 5% 4 4 4 3 5% 7% 49%	2424
	21st to end	Day	16% 7% 2 5% 3 3 4 3 5% 6% 46%	2600
May	1st to 10th	Day	13% 4 2 5% 3 4 4 3 5% 6% 51%	5900
	11th to 20th	Day	9% 4 2 4 3 3 3 3 5% 7% 58%	5862
	21st to end	Day	19% 5% 2 5% 4 4 4 3 5% 6% 44%	6446
June	1st to 10th	Day	5% 3 2 4 3 3 4 4 5% 9% 59%	2600
	11th to 20th	Day	6% 4 1 4 4 3 4 4 5% 7% 58%	2729
	21st to end	Day	5% 3 2 4 4 4 3 3 6% 7% 58%	2800
July	1st to 10th	Day	6% 4 2 5% 3 3 4 4 6% 9% 53%	6339
	11th to 20th	Day	6% 3 1 4 3 3 4 4 6% 9% 55%	5990
	21st to end	Day	6% 4 1 4 4 4 4 4 6% 8% 54%	6424
August	1st to 10th	Day	10% 6% 2 5% 3 3 4 4 6% 8% 49%	5801
	11th to 20th	Day	8% 4 1 4 3 3 4 4 6% 10% 52%	5821
	21st to end	Day	13% 5% 2 5% 3 3 4 3 5% 6% 50%	6014
September	1st to 10th	Day	10% 4 2 4 3 3 3 2 5% 5% 59%	2286
	11th to 20th	Day	8% 5% 2 5% 2 2 3 3 5% 7% 58%	2200
	21st to end	Day	7% 3 2 4 3 3 4 3 4 6% 61%	2200
October	1st to 10th	Day	9% 2 1 2 1 2 2 2 3 5% 71%	3590
	11th to 20th	Day	5% 3 1 3 3 3 3 3 5% 7% 65%	3283
	21st to end	Day	8% 5% 1 3 2 2 2 2 4 6% 64%	3322
November	1st to 10th	Day	7% 4 1 4 3 2 3 2 4 6% 64%	1853
	11th to 20th	Day	6% 6% 1 4 3 2 3 3 4 5% 64%	1890
	21st to end	Day	10% 6% 2 3 3 2 2 2 4 5% 61%	1890
December	1st to 10th	Day	4 5% 1 3 2 2 3 3 4 5% 67%	3030
	11th to 20th	Day	5% 4 2 4 3 3 3 2 4 5% 65%	3481
	21st to end	Day	10% 12% 4 8% 4 4 4 3 5% 7% 41%	4587
January	1st to 10th	Night	8% 8% 3 10% 4 4 4 3 4 7% 46%	6018
	11th to 20th	Night	4 5% 2 6% 5% 5% 4 3 4 6% 57%	6030
	21st to end	Night	7% 7% 3 7% 4 3 3 3 4 5% 53%	6633
February	1st to 10th	Night	8% 8% 3 7% 5% 4 3 3 4 6% 49%	2506
	11th to 20th	Night	6% 6% 2 7% 5% 4 4 4 6% 7% 49%	2338
	21st to end	Night	6% 6% 3 6% 3 3 3 2 4 4 59%	1980
March	1st to 10th	Night	7% 5% 1 4 3 2 2 2 4 6% 64%	5312
	11th to 20th	Night	6% 4 1 4 3 4 4 4 5% 6% 59%	4980
	21st to end	Night	9% 6% 2 6% 4 4 4 4 5% 7% 49%	5467
April	1st to 10th	Night	9% 6% 1 5% 3 3 4 3 5% 9% 53%	2070
	11th to 20th	Night	11% 4 2 6% 4 3 4 3 6% 7% 50%	1922
	21st to end	Night	15% 5% 2 4 4 3 3 4 5% 6% 50%	1800
May	1st to 10th	Night	14% 5% 2 5% 4 3 3 3 6% 7% 48%	4080
	11th to 20th	Night	9% 3 1 4 3 3 4 3 5% 7% 58%	4053
	21st to end	Night	18% 5% 2 4 3 3 4 3 5% 7% 45%	4451
June	1st to 10th	Night	5% 3 1 4 3 3 3 4 7% 11% 56%	1800
	11th to 20th	Night	6% 3 2 4 3 4 4 3 7% 9% 54%	1664
	21st to end	Night	5% 3 1 4 3 4 6% 4 6% 11% 54%	1600
July	1st to 10th	Night	7% 3 1 5% 5% 4 4 4 6% 9% 51%	3640
	11th to 20th	Night	7% 4 2 5% 5% 4 4 5% 7% 10% 46%	3983
	21st to end	Night	6% 3 2 5% 3 4 4 4 5% 9% 55%	4449
August	1st to 10th	Night	6% 4 2 6% 4 4 4 4 7% 11% 48%	4011
	11th to 20th	Night	6% 4 2 5% 4 4 5% 4 6% 9% 52%	4028
	21st to end	Night	12% 5% 2 6% 4 4 4 3 6% 8% 47%	4946
September	1st to 10th	Night	7% 3 1 4 3 3 3 3 4 6% 64%	2112
	11th to 20th	Night	8% 3 1 5% 2 3 3 3 5% 6% 60%	2200
	21st to end	Night	8% 4 1 4 3 3 3 3 5% 6% 61%	2200
October	1st to 10th	Night	6% 2 1 3 2 2 2 2 3 5% 73%	3590
	11th to 20th	Night	6% 2 1 3 2 3 2 2 5% 5% 69%	3823
	21st to end	Night	6% 3 1 3 2 2 3 2 3 7% 67%	4471
November	1st to 10th	Night	7% 3 2 3 2 3 3 2 4 5% 66%	2665
	11th to 20th	Night	7% 4 1 3 3 2 3 2 4 6% 66%	2730
	21st to end	Night	9% 6% 2 4 2 3 3 3 4 6% 59%	2730
December	1st to 10th	Night	4 5% 2 4 3 2 2 3 3 6% 67%	4380
	11th to 20th	Night	5% 3 1 3 3 3 3 3 4 7% 63%	4946
	21st to end	Night	11% 11% 4 7% 3 3 3 3 4 6% 45%	6633

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	38% 2 12% 25% 19% 4	4168
	11th to 20th	Day	39% 3 10% 23% 21% 5%	4170
	21st to end	Day	35% 2 11% 26% 22% 4	4587
February	1st to 10th	Day	38% 4 14% 25% 15% 5%	1910
	11th to 20th	Day	35% 3 15% 25% 16% 6%	1959
	21st to end	Day	28% 4 9% 26% 25% 9%	1650
March	1st to 10th	Day	28% 2 7% 18% 30% 15%	4557
	11th to 20th	Day	27% 2 7% 20% 29% 15%	4980
	21st to end	Day	31% 2 16% 37% 12% 2	5464
April	1st to 10th	Day	30% 4 9% 27% 23% 7%	2326
	11th to 20th	Day	36% 4 10% 27% 19% 5%	2427
	21st to end	Day	38% 4 11% 28% 17% 2	2600
May	1st to 10th	Day	35% 3 13% 26% 16% 7%	5900
	11th to 20th	Day	27% 3 11% 23% 23% 12%	5866
	21st to end	Day	41% 3 11% 23% 19% 2	6447
June	1st to 10th	Day	23% 4 19% 33% 16% 5%	2600
	11th to 20th	Day	25% 4 13% 29% 22% 7%	2729
	21st to end	Day	24% 4 10% 29% 25% 8%	2800
July	1st to 10th	Day	29% 3 9% 27% 26% 6%	6271
	11th to 20th	Day	28% 2 16% 27% 24% 3	5918
	21st to end	Day	27% 3 11% 31% 22% 6%	6240
August	1st to 10th	Day	33% 3 13% 26% 21% 3	4220
	11th to 20th	Day	31% 4 16% 24% 20% 5%	4210
	21st to end	Day	23% 3 13% 29% 23% 8%	4328
September	1st to 10th	Day	28% 2 9% 28% 23% 10%	2286
	11th to 20th	Day	26% 3 9% 29% 27% 5%	2200
	21st to end	Day	26% 3 10% 27% 27% 7%	2200
October	1st to 10th	Day	19% 1 5% 22% 41% 12%	3590
	11th to 20th	Day	22% 1 10% 34% 23% 10%	3283
	21st to end	Day	24% 1 6% 27% 33% 7%	3322
November	1st to 10th	Day	24% 2 9% 31% 28% 7%	1853
	11th to 20th	Day	24% 2 7% 30% 30% 6%	1890
	21st to end	Day	27% 2 10% 29% 27% 6%	1890
December	1st to 10th	Day	21% 2 11% 36% 24% 6%	3030
	11th to 20th	Day	24% 1 9% 40% 23% 2	3479
	21st to end	Day	45% 2 8% 26% 17% 3	4587
January	1st to 10th	Night	41% 1 12% 24% 18% 3	6018
	11th to 20th	Night	31% 2 10% 24% 27% 6%	6030
	21st to end	Night	36% 1 9% 24% 20% 9%	6633
February	1st to 10th	Night	37% 4 12% 24% 17% 7%	2506
	11th to 20th	Night	34% 4 12% 27% 20% 4	2338
	21st to end	Night	30% 3 8% 22% 26% 12%	1980
March	1st to 10th	Night	23% 2 6% 22% 31% 15%	5312
	11th to 20th	Night	26% 2 7% 19% 28% 18%	4980
	21st to end	Night	35% 2 15% 35% 11% 2	5467
April	1st to 10th	Night	30% 3 12% 23% 26% 5%	2070
	11th to 20th	Night	33% 3 13% 26% 21% 4	1922
	21st to end	Night	36% 3 10% 27% 20% 3	1800
May	1st to 10th	Night	37% 3 13% 25% 15% 7%	4080
	11th to 20th	Night	28% 3 12% 25% 23% 9%	4054
	21st to end	Night	38% 4 15% 24% 16% 3	4452
June	1st to 10th	Night	22% 5% 17% 31% 20% 5%	1800
	11th to 20th	Night	25% 5% 15% 27% 23% 5%	1664
	21st to end	Night	25% 5% 13% 26% 24% 6%	1600
July	1st to 10th	Night	30% 3 17% 22% 25% 3	3600
	11th to 20th	Night	32% 3 13% 25% 23% 4	3932
	21st to end	Night	27% 2 13% 29% 22% 7%	4320
August	1st to 10th	Night	29% 3 14% 28% 22% 3	2916
	11th to 20th	Night	33% 4 16% 25% 19% 3	2915
	21st to end	Night	24% 3 14% 30% 21% 8%	3563
September	1st to 10th	Night	24% 3 12% 25% 27% 10%	2112
	11th to 20th	Night	26% 4 9% 25% 29% 8%	2200
	21st to end	Night	25% 3 8% 24% 30% 9%	2200
October	1st to 10th	Night	18% 2 5% 19% 46% 11%	3590
	11th to 20th	Night	19% 2 9% 26% 32% 13%	3823
	21st to end	Night	20% 2 7% 26% 36% 9%	4471
November	1st to 10th	Night	22% 3 8% 29% 29% 10%	2665
	11th to 20th	Night	22% 2 9% 29% 30% 8%	2730
	21st to end	Night	29% 2 10% 27% 23% 9%	2730
December	1st to 10th	Night	22% 2 11% 37% 24% 4	4380
	11th to 20th	Night	23% 1 7% 38% 25% 5%	4947
	21st to end	Night	42% 1 9% 30% 15% 3	6633

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	12% 10% 37% 32% 8% 1	330
	11th to 20th	Day	13% 13% 39% 28% 7%	330
	21st to end	Day	9% 9% 48% 26% 8%	363
February	1st to 10th	Day	15% 14% 44% 22% 4	300
	11th to 20th	Day	12% 12% 47% 20% 7% 2	300
	21st to end	Day	10% 19% 49% 19% 4	249
March	1st to 10th	Day	12% 12% 44% 25% 6%	300
	11th to 20th	Day	18% 15% 37% 20% 9% 1	300
	21st to end	Day	18% 12% 45% 19% 5% 1	330
April	1st to 10th	Day	15% 19% 42% 18% 6% 1	426
	11th to 20th	Day	12% 19% 41% 24% 4	545
	21st to end	Day	21% 14% 38% 20% 6% 1	700
May	1st to 10th	Day	13% 12% 33% 30% 11% 1	703
	11th to 20th	Day	14% 10% 34% 26% 14% 2	725
	21st to end	Day	16% 8% 31% 32% 10% 2	789
June	1st to 10th	Day	6% 5% 27% 36% 18% 8%	730
	11th to 20th	Day	6% 5% 33% 36% 16% 2	730
	21st to end	Day	6% 5% 33% 38% 16% 1	730
July	1st to 10th	Day	8% 2 21% 40% 24% 6%	721
	11th to 20th	Day	4 2 20% 44% 26% 4	718
	21st to end	Day	8% 1 15% 43% 28% 5%	794
August	1st to 10th	Day	9% 2 17% 44% 24% 4	726
	11th to 20th	Day	8% 3 21% 41% 26% 3	715
	21st to end	Day	8% 2 19% 42% 24% 5%	600
September	1st to 10th	Day	10% 3 19% 44% 21% 3	416
	11th to 20th	Day	6% 6% 25% 39% 18% 6%	330
	21st to end	Day	12% 5% 28% 31% 20% 4	330
October	1st to 10th	Day	18% 7% 25% 28% 17% 4	330
	11th to 20th	Day	5% 11% 43% 25% 13% 3	330
	21st to end	Day	18% 14% 32% 24% 10% 2	363
November	1st to 10th	Day	14% 10% 39% 26% 10% 1	330
	11th to 20th	Day	12% 12% 39% 25% 10% 2	330
	21st to end	Day	18% 9% 36% 23% 12% 2	330
December	1st to 10th	Day	10% 8% 42% 28% 11% 2	330
	11th to 20th	Day	13% 11% 42% 26% 8% 1	330
	21st to end	Day	17% 12% 40% 25% 6%	363
January	1st to 10th	Night	10% 8% 39% 37% 6%	1050
	11th to 20th	Night	8% 12% 39% 33% 8% 1	1050
	21st to end	Night	9% 9% 43% 33% 5%	1155
February	1st to 10th	Night	12% 8% 42% 31% 6%	906
	11th to 20th	Night	11% 12% 41% 32% 5%	784
	21st to end	Night	10% 13% 44% 28% 5%	660
March	1st to 10th	Night	11% 15% 38% 32% 4	777
	11th to 20th	Night	15% 9% 37% 33% 6% 1	600
	21st to end	Night	18% 13% 40% 24% 4	660
April	1st to 10th	Night	13% 14% 43% 26% 4	600
	11th to 20th	Night	15% 17% 38% 26% 4	593
	21st to end	Night	18% 14% 33% 29% 6%	600
May	1st to 10th	Night	14% 10% 38% 32% 7%	600
	11th to 20th	Night	14% 9% 32% 34% 10% 1	591
	21st to end	Night	14% 8% 38% 29% 11%	650
June	1st to 10th	Night	7% 6% 37% 36% 14% 1	600
	11th to 20th	Night	6% 7% 38% 40% 9%	600
	21st to end	Night	6% 5% 39% 41% 10%	600
July	1st to 10th	Night	7% 2 27% 46% 18% 1	585
	11th to 20th	Night	5% 1 24% 50% 19% 1	582
	21st to end	Night	8% 1 18% 49% 22% 1	657
August	1st to 10th	Night	6% 2 22% 51% 19%	597
	11th to 20th	Night	8% 2 24% 48% 18% 1	594
	21st to end	Night	5% 2 24% 48% 20% 2	660
September	1st to 10th	Night	8% 2 28% 47% 15% 1	600
	11th to 20th	Night	10% 3 33% 39% 14% 1	600
	21st to end	Night	9% 5% 31% 40% 14% 2	600
October	1st to 10th	Night	13% 8% 31% 35% 13% 1	600
	11th to 20th	Night	11% 8% 39% 33% 9%	750
	21st to end	Night	13% 11% 33% 31% 11% 1	1011
November	1st to 10th	Night	9% 9% 34% 39% 9%	1025
	11th to 20th	Night	9% 10% 40% 32% 8%	1050
	21st to end	Night	13% 8% 32% 35% 10% 1	1050
December	1st to 10th	Night	9% 8% 38% 37% 7%	1050
	11th to 20th	Night	11% 11% 38% 33% 7%	1050
	21st to end	Night	13% 11% 35% 35% 6%	1155

Page generated at 2026-01-29 00:21:43. Version ac07

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