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 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% 5% 2 4 4 2 4 4 5% 7% 54%	75407
	Night	8% 5% 2 4 4 2 4 4 5% 7% 56%	74367
Transparency	Day	30% 4 12% 28% 21% 5%	75127
	Night	29% 4 12% 27% 23% 6%	74170
Seeing	Day	11% 8% 31% 32% 15% 3	14460
	Night	10% 8% 35% 36% 10% 1	24508

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	5% 5% 2 5% 4 3 3 4 6% 7% 56%	1707
	11th to 20th	Day	7% 7% 3 4 4 2 4 4 5% 8% 53%	1647
	21st to end	Day	5% 5% 3 6% 6% 3 4 4 4 6% 52%	1782
February	1st to 10th	Day	7% 8% 4 6% 4 3 4 3 4 6% 50%	1719
	11th to 20th	Day	5% 6% 2 5% 6% 4 5% 5% 5% 6% 51%	1749
	21st to end	Day	8% 6% 2 4 5% 3 4 4 5% 5% 55%	1480
March	1st to 10th	Day	7% 5% 2 4 4 2 4 5% 5% 7% 55%	1818
	11th to 20th	Day	12% 8% 3 5% 4 2 3 4 3 6% 51%	1980
	21st to end	Day	12% 7% 3 4 3 3 4 5% 5% 6% 47%	2178
April	1st to 10th	Day	9% 4 2 4 4 3 4 4 5% 6% 55%	2092
	11th to 20th	Day	10% 7% 3 5% 4 4 4 4 5% 7% 47%	2178
	21st to end	Day	15% 6% 2 4 4 2 4 4 5% 7% 46%	2340
May	1st to 10th	Day	13% 5% 2 5% 4 3 4 4 5% 8% 47%	2340
	11th to 20th	Day	11% 5% 2 4 4 2 4 4 5% 8% 51%	2302
	21st to end	Day	12% 3 2 5% 5% 3 5% 5% 6% 8% 45%	2531
June	1st to 10th	Day	5% 2 2 3 4 2 4 5% 5% 9% 60%	2340
	11th to 20th	Day	6% 3 1 4 4 2 4 5% 5% 7% 58%	2455
	21st to end	Day	5% 3 2 3 4 3 4 4 6% 8% 59%	2520
July	1st to 10th	Day	6% 3 2 4 4 3 4 5% 6% 8% 55%	2520
	11th to 20th	Day	4 3 1 2 3 2 4 5% 6% 9% 60%	2378
	21st to end	Day	7% 3 1 4 5% 2 5% 5% 7% 10% 50%	2546
August	1st to 10th	Day	8% 5% 2 4 4 2 4 5% 6% 9% 50%	2328
	11th to 20th	Day	6% 4 1 4 4 2 4 6% 6% 8% 54%	2301
	21st to end	Day	6% 4 1 3 3 2 4 5% 5% 7% 62%	2392
September	1st to 10th	Day	11% 4 2 3 3 2 3 3 5% 4 59%	2058
	11th to 20th	Day	9% 4 2 4 2 1 3 4 5% 6% 59%	1980
	21st to end	Day	7% 3 1 4 4 2 4 4 4 6% 61%	1980
October	1st to 10th	Day	16% 4 1 2 3 2 2 3 3 7% 57%	1980
	11th to 20th	Day	8% 4 1 3 3 2 3 3 3 5% 66%	1828
	21st to end	Day	10% 6% 2 3 2 1 2 3 4 6% 60%	1859
November	1st to 10th	Day	6% 3 1 4 3 1 3 3 4 6% 64%	1673
	11th to 20th	Day	6% 5% 2 3 3 2 3 3 4 5% 64%	1710
	21st to end	Day	10% 6% 2 3 3 2 2 3 4 5% 62%	1710
December	1st to 10th	Day	6% 7% 2 4 4 3 3 5% 5% 7% 54%	1710
	11th to 20th	Day	7% 6% 3 5% 4 2 3 3 4 6% 56%	2161
	21st to end	Day	10% 13% 5% 8% 5% 3 4 4 4 6% 39%	3135
January	1st to 10th	Night	5% 7% 3 6% 5% 2 3 4 3 6% 56%	2458
	11th to 20th	Night	6% 5% 3 6% 4 2 3 4 5% 6% 56%	2392
	21st to end	Night	6% 6% 2 4 4 3 4 4 4 6% 57%	2574
February	1st to 10th	Night	7% 8% 4 7% 5% 3 4 4 4 5% 50%	2254
	11th to 20th	Night	6% 5% 3 6% 5% 3 5% 5% 5% 8% 50%	2098
	21st to end	Night	7% 6% 3 6% 5% 2 4 3 4 4 57%	1776
March	1st to 10th	Night	7% 5% 2 4 3 2 3 4 5% 8% 56%	2140
	11th to 20th	Night	11% 5% 2 4 4 3 3 3 4 6% 55%	1980
	21st to end	Night	13% 7% 3 5% 4 3 4 4 5% 7% 46%	2178
April	1st to 10th	Night	9% 5% 1 4 4 2 4 3 5% 8% 54%	1864
	11th to 20th	Night	12% 4 2 4 5% 2 4 4 5% 8% 49%	1728
	21st to end	Night	14% 4 2 3 4 2 3 4 5% 6% 52%	1620
May	1st to 10th	Night	12% 6% 3 5% 6% 3 4 4 6% 6% 45%	1620
	11th to 20th	Night	13% 3 2 4 3 2 2 3 5% 10% 52%	1593
	21st to end	Night	10% 4 2 4 6% 2 4 5% 6% 11% 44%	1745
June	1st to 10th	Night	5% 3 1 3 3 3 3 5% 6% 11% 57%	1620
	11th to 20th	Night	7% 2 2 4 4 3 5% 4 7% 10% 54%	1498
	21st to end	Night	5% 2 2 4 4 3 6% 5% 6% 11% 54%	1440
July	1st to 10th	Night	6% 3 2 4 5% 3 5% 6% 7% 8% 51%	1440
	11th to 20th	Night	3 3 1 3 3 2 4 6% 6% 10% 60%	1575
	21st to end	Night	7% 3 2 4 4 4 5% 5% 7% 12% 48%	1772
August	1st to 10th	Night	4 3 2 4 5% 3 5% 5% 7% 11% 49%	1611
	11th to 20th	Night	7% 4 1 3 5% 3 4 4 6% 9% 55%	1600
	21st to end	Night	5% 2 1 3 4 3 3 4 5% 7% 63%	1961
September	1st to 10th	Night	7% 3 1 4 4 2 3 4 4 6% 62%	1900
	11th to 20th	Night	8% 3 1 4 3 2 3 4 5% 6% 61%	1980
	21st to end	Night	7% 3 1 3 4 2 4 4 5% 6% 62%	1980
October	1st to 10th	Night	11% 4 2 4 3 2 3 3 3 6% 59%	1980
	11th to 20th	Night	9% 3 2 3 3 1 3 3 4 4 65%	2114
	21st to end	Night	9% 4 2 3 2 2 3 3 3 5% 63%	2493
November	1st to 10th	Night	5% 3 2 3 3 2 3 3 4 5% 68%	2405
	11th to 20th	Night	7% 3 1 2 3 2 3 3 4 5% 65%	2470
	21st to end	Night	8% 6% 2 4 3 2 3 4 4 5% 59%	2470
December	1st to 10th	Night	6% 5% 2 4 4 3 3 4 4 8% 58%	2470
	11th to 20th	Night	7% 3 2 4 4 2 3 4 4 7% 59%	3036
	21st to end	Night	11% 12% 4 5% 4 2 3 3 4 6% 45%	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	28% 3 14% 31% 21% 3	1708
	11th to 20th	Day	32% 4 14% 29% 18% 4	1647
	21st to end	Day	33% 3 14% 32% 14% 4	1782
February	1st to 10th	Day	37% 4 15% 25% 14% 5%	1719
	11th to 20th	Day	35% 4 15% 25% 16% 6%	1759
	21st to end	Day	30% 4 10% 26% 23% 7%	1480
March	1st to 10th	Day	28% 3 11% 26% 24% 7%	1818
	11th to 20th	Day	37% 3 9% 22% 21% 6%	1980
	21st to end	Day	37% 5% 14% 27% 14% 3	2178
April	1st to 10th	Day	30% 4 10% 26% 22% 7%	2092
	11th to 20th	Day	37% 4 11% 28% 16% 4	2181
	21st to end	Day	37% 4 11% 29% 17% 2	2340
May	1st to 10th	Day	36% 4 12% 27% 16% 4	2340
	11th to 20th	Day	33% 4 18% 30% 14% 1	2306
	21st to end	Day	36% 7% 18% 24% 12% 3	2531
June	1st to 10th	Day	23% 5% 19% 34% 15% 5%	2340
	11th to 20th	Day	25% 4 13% 29% 21% 7%	2455
	21st to end	Day	23% 4 10% 31% 24% 8%	2520
July	1st to 10th	Day	26% 5% 11% 30% 24% 4	2451
	11th to 20th	Day	21% 4 12% 30% 26% 6%	2306
	21st to end	Day	26% 6% 15% 33% 17% 2	2405
August	1st to 10th	Day	30% 5% 17% 30% 14% 4	2314
	11th to 20th	Day	27% 5% 14% 29% 19% 6%	2301
	21st to end	Day	22% 5% 11% 26% 28% 8%	2392
September	1st to 10th	Day	29% 2 9% 26% 23% 11%	2058
	11th to 20th	Day	26% 4 9% 28% 28% 5%	1980
	21st to end	Day	25% 4 11% 28% 26% 6%	1980
October	1st to 10th	Day	30% 2 9% 27% 26% 5%	1980
	11th to 20th	Day	23% 2 8% 27% 29% 11%	1828
	21st to end	Day	28% 2 9% 26% 27% 8%	1859
November	1st to 10th	Day	23% 3 9% 30% 27% 8%	1673
	11th to 20th	Day	24% 2 7% 30% 30% 6%	1710
	21st to end	Day	27% 2 8% 28% 29% 6%	1710
December	1st to 10th	Day	30% 4 13% 27% 22% 4	1710
	11th to 20th	Day	31% 2 10% 35% 20% 2	2159
	21st to end	Day	48% 2 9% 21% 16% 3	3135
January	1st to 10th	Night	32% 3 11% 29% 22% 3	2458
	11th to 20th	Night	30% 3 10% 28% 23% 4	2392
	21st to end	Night	30% 3 12% 31% 20% 4	2574
February	1st to 10th	Night	37% 4 12% 23% 17% 7%	2254
	11th to 20th	Night	33% 4 12% 27% 20% 4	2098
	21st to end	Night	32% 3 8% 22% 24% 11%	1776
March	1st to 10th	Night	27% 3 10% 23% 27% 9%	2140
	11th to 20th	Night	32% 3 9% 26% 22% 8%	1980
	21st to end	Night	38% 4 13% 26% 15% 4	2178
April	1st to 10th	Night	30% 4 13% 23% 26% 5%	1864
	11th to 20th	Night	33% 4 14% 27% 19% 3	1728
	21st to end	Night	34% 3 11% 28% 21% 3	1620
May	1st to 10th	Night	40% 5% 12% 21% 18% 5%	1620
	11th to 20th	Night	30% 4 20% 28% 17% 2	1594
	21st to end	Night	34% 6% 22% 25% 11% 2	1746
June	1st to 10th	Night	21% 6% 17% 32% 20% 4	1620
	11th to 20th	Night	25% 5% 15% 26% 23% 6%	1498
	21st to end	Night	25% 5% 14% 26% 24% 6%	1440
July	1st to 10th	Night	27% 6% 13% 27% 22% 5%	1400
	11th to 20th	Night	18% 5% 16% 27% 26% 7%	1524
	21st to end	Night	29% 4 15% 29% 20% 3	1673
August	1st to 10th	Night	27% 6% 16% 32% 15% 3	1601
	11th to 20th	Night	26% 5% 18% 28% 20% 5%	1600
	21st to end	Night	21% 4 11% 28% 26% 9%	1961
September	1st to 10th	Night	24% 3 11% 25% 27% 11%	1900
	11th to 20th	Night	25% 4 9% 24% 30% 9%	1980
	21st to end	Night	24% 4 9% 24% 31% 9%	1980
October	1st to 10th	Night	28% 3 9% 24% 28% 7%	1980
	11th to 20th	Night	23% 3 7% 23% 31% 13%	2114
	21st to end	Night	26% 3 9% 24% 27% 12%	2493
November	1st to 10th	Night	21% 3 8% 29% 29% 11%	2405
	11th to 20th	Night	23% 2 8% 29% 30% 8%	2470
	21st to end	Night	29% 2 9% 26% 24% 10%	2470
December	1st to 10th	Night	27% 3 14% 28% 23% 5%	2470
	11th to 20th	Night	27% 2 9% 38% 22% 3	3037
	21st to end	Night	42% 2 11% 28% 14% 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	10% 10% 40% 31% 9% 1	270
	11th to 20th	Day	14% 11% 40% 27% 8%	249
	21st to end	Day	9% 11% 50% 23% 6%	264
February	1st to 10th	Day	14% 15% 45% 23% 4	240
	11th to 20th	Day	12% 11% 48% 21% 7% 1	240
	21st to end	Day	12% 19% 46% 19% 5%	198
March	1st to 10th	Day	8% 12% 50% 25% 6%	240
	11th to 20th	Day	20% 15% 33% 20% 10% 2	240
	21st to end	Day	19% 11% 47% 18% 5% 1	264
April	1st to 10th	Day	12% 18% 45% 19% 6% 1	352
	11th to 20th	Day	12% 16% 42% 25% 5%	459
	21st to end	Day	20% 15% 37% 21% 6% 2	600
May	1st to 10th	Day	14% 11% 33% 31% 11% 1	603
	11th to 20th	Day	15% 9% 34% 25% 14% 2	625
	21st to end	Day	15% 8% 31% 33% 10% 2	679
June	1st to 10th	Day	4 5% 26% 37% 20% 8%	630
	11th to 20th	Day	6% 5% 32% 37% 17% 3	630
	21st to end	Day	5% 5% 31% 40% 18% 1	630
July	1st to 10th	Day	7% 2 20% 40% 25% 6%	621
	11th to 20th	Day	3 2 19% 45% 27% 4	618
	21st to end	Day	8% 14% 43% 30% 5%	684
August	1st to 10th	Day	8% 2 15% 45% 26% 4	626
	11th to 20th	Day	7% 3 20% 41% 27% 2	615
	21st to end	Day	5% 3 20% 42% 25% 5%	511
September	1st to 10th	Day	11% 3 20% 40% 24% 3	348
	11th to 20th	Day	6% 5% 22% 41% 21% 6%	270
	21st to end	Day	13% 6% 30% 31% 18% 2	270
October	1st to 10th	Day	21% 8% 25% 26% 17% 3	270
	11th to 20th	Day	3 12% 40% 27% 13% 3	270
	21st to end	Day	17% 14% 33% 24% 10% 2	297
November	1st to 10th	Day	11% 10% 39% 26% 11% 1	270
	11th to 20th	Day	11% 11% 41% 25% 10% 2	270
	21st to end	Day	17% 9% 34% 25% 13% 2	270
December	1st to 10th	Day	10% 9% 39% 29% 11% 2	270
	11th to 20th	Day	14% 10% 40% 28% 8% 1	270
	21st to end	Day	19% 13% 42% 22% 4	297
January	1st to 10th	Night	10% 8% 39% 37% 7%	950
	11th to 20th	Night	8% 12% 37% 33% 9% 1	920
	21st to end	Night	10% 9% 44% 33% 4	990
February	1st to 10th	Night	12% 8% 42% 31% 6%	814
	11th to 20th	Night	10% 11% 42% 32% 5%	704
	21st to end	Night	10% 14% 43% 28% 5%	592
March	1st to 10th	Night	10% 15% 38% 32% 5%	700
	11th to 20th	Night	15% 9% 37% 32% 6% 1	540
	21st to end	Night	20% 12% 40% 25% 4 1	594
April	1st to 10th	Night	13% 13% 44% 26% 4	540
	11th to 20th	Night	15% 15% 38% 27% 5%	533
	21st to end	Night	16% 14% 34% 30% 6%	540
May	1st to 10th	Night	13% 10% 40% 31% 6%	540
	11th to 20th	Night	15% 10% 31% 33% 9% 1	531
	21st to end	Night	13% 8% 38% 29% 11%	584
June	1st to 10th	Night	6% 6% 37% 36% 14% 1	540
	11th to 20th	Night	6% 8% 38% 39% 9%	540
	21st to end	Night	5% 4 37% 42% 11%	540
July	1st to 10th	Night	6% 2 26% 46% 19% 1	525
	11th to 20th	Night	5% 1 23% 51% 20% 1	522
	21st to end	Night	8% 1 17% 49% 23% 1	591
August	1st to 10th	Night	6% 2 20% 51% 21%	537
	11th to 20th	Night	8% 2 23% 49% 18% 1	534
	21st to end	Night	4 2 23% 49% 21% 2	594
September	1st to 10th	Night	8% 2 29% 46% 14% 1	540
	11th to 20th	Night	10% 3 33% 39% 15% 1	540
	21st to end	Night	8% 5% 33% 39% 13% 2	540
October	1st to 10th	Night	13% 8% 31% 35% 12% 1	540
	11th to 20th	Night	12% 7% 38% 33% 10%	674
	21st to end	Night	12% 10% 34% 31% 12% 1	909
November	1st to 10th	Night	8% 8% 34% 40% 9% 1	925
	11th to 20th	Night	10% 10% 41% 32% 8%	950
	21st to end	Night	13% 8% 32% 35% 11% 1	950
December	1st to 10th	Night	9% 8% 39% 37% 7%	950
	11th to 20th	Night	12% 10% 37% 34% 8%	950
	21st to end	Night	13% 11% 36% 35% 6%	1045

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