Grand Island KOA Journey
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Grand Island KOA Journey clear sky chart from 2005-11-06 to 2026-09-14.

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	9% 7% 2 6% 4 4 4 3 5% 7% 48%	158293
	Night	8% 6% 2 6% 4 4 4 3 5% 7% 51%	150216
Transparency	Day	34% 6% 13% 25% 18% 3	153017
	Night	32% 5% 13% 26% 20% 4	146504
Seeing	Day	13% 10% 32% 30% 13% 2	18379
	Night	11% 9% 36% 33% 9%	28153

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% 12% 4 10% 6% 5% 4 3 4 5% 39%	4720
	11th to 20th	Day	4 8% 3 8% 6% 5% 5% 4 6% 6% 44%	5252
	21st to end	Day	5% 9% 4 11% 5% 4 4 3 4 5% 45%	5812
February	1st to 10th	Day	8% 11% 4 8% 6% 4 5% 4 6% 8% 38%	1890
	11th to 20th	Day	6% 9% 3 7% 4 3 4 4 6% 7% 46%	2028
	21st to end	Day	8% 7% 2 5% 4 4 3 4 5% 6% 52%	1730
March	1st to 10th	Day	12% 8% 3 5% 3 2 3 2 3 4 56%	4752
	11th to 20th	Day	9% 7% 2 5% 3 3 3 3 4 6% 54%	5090
	21st to end	Day	13% 10% 3 8% 4 4 4 4 5% 7% 38%	5585
April	1st to 10th	Day	12% 8% 2 6% 4 4 3 3 5% 7% 47%	2383
	11th to 20th	Day	12% 8% 1 6% 4 4 4 3 5% 7% 45%	2643
	21st to end	Day	18% 8% 2 6% 4 4 5% 2 5% 6% 40%	2730
May	1st to 10th	Day	10% 6% 2 5% 3 3 4 4 6% 8% 47%	7655
	11th to 20th	Day	11% 6% 2 5% 3 3 3 3 5% 6% 52%	7627
	21st to end	Day	17% 8% 3 7% 4 4 4 4 5% 7% 39%	8404
June	1st to 10th	Day	7% 4 2 4 4 4 4 5% 6% 9% 52%	2734
	11th to 20th	Day	8% 5% 2 4 5% 3 4 4 6% 7% 52%	2940
	21st to end	Day	7% 4 2 4 4 4 5% 4 7% 9% 51%	2940
July	1st to 10th	Day	7% 5% 2 6% 4 4 5% 4 7% 8% 49%	8249
	11th to 20th	Day	4 4 2 4 3 4 4 3 5% 7% 59%	7948
	21st to end	Day	8% 6% 2 6% 4 4 5% 5% 7% 9% 44%	8339
August	1st to 10th	Day	7% 5% 2 7% 5% 4 5% 4 6% 8% 47%	7581
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 4 7% 10% 42%	7598
	21st to end	Day	10% 6% 2 6% 5% 4 5% 3 5% 8% 46%	8233
September	1st to 10th	Day	11% 5% 2 5% 4 3 3 3 4 6% 54%	2367
	11th to 20th	Day	8% 4 2 5% 3 4 3 3 5% 7% 55%	2233
	21st to end	Day	9% 4 1 3 2 3 3 2 5% 6% 60%	2200
October	1st to 10th	Day	9% 3 1 3 2 2 2 2 3 4 69%	3503
	11th to 20th	Day	7% 4 1 3 3 2 3 3 4 6% 65%	3240
	21st to end	Day	10% 5% 2 4 3 3 3 3 5% 6% 56%	3359
November	1st to 10th	Day	7% 5% 1 5% 3 4 3 3 6% 7% 56%	1853
	11th to 20th	Day	7% 6% 2 5% 4 3 3 3 4 6% 56%	1890
	21st to end	Day	11% 8% 2 6% 3 3 4 3 5% 7% 49%	1890
December	1st to 10th	Day	4 5% 2 6% 4 3 4 4 5% 6% 56%	3030
	11th to 20th	Day	5% 8% 3 7% 5% 4 4 4 5% 6% 48%	3481
	21st to end	Day	12% 10% 3 11% 5% 4 4 3 5% 6% 37%	4384
January	1st to 10th	Night	7% 12% 4 11% 5% 4 4 4 6% 6% 38%	8201
	11th to 20th	Night	4 6% 2 7% 5% 5% 5% 4 6% 7% 49%	7704
	21st to end	Night	6% 9% 4 11% 4 4 4 4 4 5% 45%	8402
February	1st to 10th	Night	8% 10% 3 7% 5% 4 4 4 5% 5% 44%	2730
	11th to 20th	Night	5% 8% 3 8% 5% 5% 4 5% 5% 6% 45%	2496
	21st to end	Night	6% 7% 2 6% 4 3 4 3 5% 6% 54%	2076
March	1st to 10th	Night	10% 5% 2 5% 3 4 4 3 4 5% 55%	5335
	11th to 20th	Night	9% 5% 2 4 3 3 3 2 4 5% 59%	5090
	21st to end	Night	11% 8% 3 6% 4 4 5% 4 6% 8% 41%	5588
April	1st to 10th	Night	11% 7% 2 5% 4 3 4 3 5% 7% 48%	2232
	11th to 20th	Night	11% 7% 2 5% 4 4 4 4 6% 8% 46%	1923
	21st to end	Night	15% 6% 2 5% 3 3 4 4 5% 7% 48%	1890
May	1st to 10th	Night	13% 7% 2 5% 3 3 4 3 4 7% 49%	5292
	11th to 20th	Night	8% 5% 2 5% 3 3 3 3 5% 7% 54%	5265
	21st to end	Night	16% 7% 2 7% 4 4 4 3 5% 7% 42%	5803
June	1st to 10th	Night	5% 5% 2 4 4 4 4 4 6% 10% 52%	1880
	11th to 20th	Night	7% 4 2 5% 3 4 3 3 6% 8% 56%	1680
	21st to end	Night	5% 4 2 4 4 2 3 4 7% 9% 56%	1680
July	1st to 10th	Night	7% 5% 2 6% 4 3 4 4 6% 8% 50%	4740
	11th to 20th	Night	5% 3 1 4 3 4 4 3 6% 8% 58%	5038
	21st to end	Night	7% 5% 2 5% 4 4 4 4 7% 10% 47%	5770
August	1st to 10th	Night	4 4 1 5% 3 4 4 3 6% 11% 55%	5241
	11th to 20th	Night	7% 4 2 6% 4 4 4 4 7% 11% 48%	5258
	21st to end	Night	7% 4 2 6% 4 5% 6% 4 7% 11% 44%	5979
September	1st to 10th	Night	8% 3 2 4 2 3 3 3 4 6% 62%	2252
	11th to 20th	Night	7% 3 2 5% 4 3 4 3 5% 8% 57%	2233
	21st to end	Night	7% 4 2 4 4 3 4 3 5% 6% 59%	2200
October	1st to 10th	Night	9% 3 1 3 2 2 2 2 4 5% 69%	3642
	11th to 20th	Night	6% 3 1 4 3 3 3 3 4 6% 65%	3899
	21st to end	Night	9% 4 2 4 3 3 2 3 4 7% 58%	4433
November	1st to 10th	Night	6% 4 2 4 2 3 3 3 5% 7% 62%	2665
	11th to 20th	Night	7% 5% 2 4 4 3 3 3 5% 7% 57%	2730
	21st to end	Night	9% 6% 2 5% 3 3 3 3 4 7% 55%	2730
December	1st to 10th	Night	3 5% 2 3 3 3 4 3 5% 7% 61%	4380
	11th to 20th	Night	7% 4 2 5% 4 4 4 4 6% 8% 51%	4946
	21st to end	Night	12% 11% 3 10% 4 4 4 3 4 6% 39%	6813

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	47% 5% 11% 22% 13% 1	4723
	11th to 20th	Day	39% 6% 15% 19% 19% 3	5252
	21st to end	Day	42% 4 12% 25% 14% 2	5812
February	1st to 10th	Day	43% 7% 16% 21% 10% 2	1890
	11th to 20th	Day	37% 5% 15% 24% 15% 4	2038
	21st to end	Day	32% 6% 11% 28% 18% 5%	1730
March	1st to 10th	Day	33% 4 8% 23% 24% 7%	4752
	11th to 20th	Day	31% 4 9% 24% 25% 7%	5090
	21st to end	Day	43% 8% 20% 21% 7% 2	5585
April	1st to 10th	Day	36% 6% 15% 25% 16% 2	2383
	11th to 20th	Day	37% 6% 14% 23% 16% 3	2646
	21st to end	Day	43% 7% 12% 23% 14% 1	2730
May	1st to 10th	Day	32% 6% 12% 24% 23% 2	7655
	11th to 20th	Day	32% 6% 11% 24% 21% 6%	7631
	21st to end	Day	43% 7% 11% 25% 14% 1	8405
June	1st to 10th	Day	26% 9% 17% 31% 15% 2	2734
	11th to 20th	Day	29% 8% 14% 27% 19% 3	2940
	21st to end	Day	27% 8% 15% 27% 19% 4	2940
July	1st to 10th	Day	31% 6% 13% 30% 19% 1	8181
	11th to 20th	Day	23% 6% 12% 29% 21% 8%	7874
	21st to end	Day	34% 8% 17% 23% 15% 3	8155
August	1st to 10th	Day	32% 7% 13% 25% 19% 3	6000
	11th to 20th	Day	40% 8% 17% 23% 12% 1	5987
	21st to end	Day	30% 6% 20% 23% 16% 5%	6456
September	1st to 10th	Day	31% 6% 13% 24% 21% 6%	2367
	11th to 20th	Day	28% 6% 12% 30% 21% 2	2233
	21st to end	Day	25% 5% 10% 32% 26% 3	2200
October	1st to 10th	Day	21% 3 5% 21% 43% 6%	3503
	11th to 20th	Day	22% 3 11% 35% 21% 9%	3240
	21st to end	Day	30% 3 10% 29% 25% 3	3359
November	1st to 10th	Day	27% 5% 15% 28% 23% 3	1853
	11th to 20th	Day	30% 4 11% 27% 24% 4	1890
	21st to end	Day	36% 4 13% 26% 18% 3	1890
December	1st to 10th	Day	29% 5% 13% 32% 19% 3	3030
	11th to 20th	Day	35% 5% 18% 27% 13% 1	3479
	21st to end	Day	47% 5% 10% 26% 11% 1	4384
January	1st to 10th	Night	45% 5% 11% 20% 16% 2	8202
	11th to 20th	Night	32% 5% 15% 26% 21% 2	7704
	21st to end	Night	41% 5% 11% 21% 19% 4	8402
February	1st to 10th	Night	41% 7% 13% 23% 14% 3	2730
	11th to 20th	Night	37% 7% 14% 24% 15% 3	2496
	21st to end	Night	30% 4 12% 22% 24% 8%	2076
March	1st to 10th	Night	30% 4 8% 26% 26% 6%	5335
	11th to 20th	Night	27% 4 8% 20% 32% 10%	5090
	21st to end	Night	40% 8% 19% 24% 8% 1	5588
April	1st to 10th	Night	35% 6% 14% 24% 19% 2	2232
	11th to 20th	Night	34% 6% 14% 26% 16% 3	1923
	21st to end	Night	35% 8% 12% 26% 17% 2	1890
May	1st to 10th	Night	35% 4 10% 27% 22% 2	5293
	11th to 20th	Night	29% 6% 13% 24% 22% 6%	5266
	21st to end	Night	40% 8% 13% 24% 15% 1	5805
June	1st to 10th	Night	25% 10% 17% 28% 17% 2	1880
	11th to 20th	Night	26% 7% 15% 28% 19% 6%	1680
	21st to end	Night	23% 7% 17% 29% 21% 3	1680
July	1st to 10th	Night	31% 6% 14% 32% 15% 2	4700
	11th to 20th	Night	25% 5% 11% 29% 20% 9%	4989
	21st to end	Night	31% 7% 17% 24% 19% 4	5641
August	1st to 10th	Night	24% 6% 16% 29% 21% 5%	4146
	11th to 20th	Night	34% 8% 22% 24% 11% 1	4145
	21st to end	Night	27% 7% 21% 28% 12% 6%	4687
September	1st to 10th	Night	23% 5% 11% 28% 24% 9%	2252
	11th to 20th	Night	26% 5% 12% 30% 23% 4	2233
	21st to end	Night	25% 5% 10% 27% 29% 4	2200
October	1st to 10th	Night	19% 4 7% 18% 45% 8%	3642
	11th to 20th	Night	21% 4 10% 29% 26% 10%	3899
	21st to end	Night	27% 3 10% 29% 27% 4	4433
November	1st to 10th	Night	22% 5% 13% 29% 25% 6%	2665
	11th to 20th	Night	28% 4 11% 29% 23% 5%	2730
	21st to end	Night	30% 4 13% 27% 22% 3	2730
December	1st to 10th	Night	23% 4 15% 36% 20% 2	4380
	11th to 20th	Night	31% 4 14% 33% 16% 1	4947
	21st to end	Night	45% 5% 11% 26% 12% 1	6813

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% 15% 35% 25% 7% 1	330
	11th to 20th	Day	15% 18% 35% 25% 6% 1	330
	21st to end	Day	14% 11% 45% 22% 7% 1	363
February	1st to 10th	Day	14% 14% 48% 19% 5%	330
	11th to 20th	Day	13% 10% 47% 24% 5% 1	330
	21st to end	Day	12% 17% 49% 17% 4	273
March	1st to 10th	Day	14% 13% 47% 22% 3 1	330
	11th to 20th	Day	22% 12% 37% 20% 9%	330
	21st to end	Day	24% 17% 40% 16% 3	363
April	1st to 10th	Day	18% 21% 40% 17% 3	403
	11th to 20th	Day	19% 16% 37% 23% 5%	684
	21st to end	Day	22% 17% 31% 21% 8% 1	750
May	1st to 10th	Day	14% 12% 34% 28% 10% 2	753
	11th to 20th	Day	17% 12% 32% 25% 11% 3	775
	21st to end	Day	17% 10% 32% 28% 12% 1	844
June	1st to 10th	Day	6% 7% 28% 35% 19% 5%	780
	11th to 20th	Day	10% 7% 35% 32% 14% 2	780
	21st to end	Day	9% 7% 34% 33% 15% 2	780
July	1st to 10th	Day	9% 4 20% 37% 25% 5%	771
	11th to 20th	Day	5% 2 20% 43% 24% 6%	768
	21st to end	Day	7% 3 20% 39% 26% 4	849
August	1st to 10th	Day	8% 3 20% 45% 21% 3	776
	11th to 20th	Day	6% 5% 19% 45% 22% 2	765
	21st to end	Day	10% 3 22% 39% 22% 4	800
September	1st to 10th	Day	12% 5% 27% 37% 15% 4	417
	11th to 20th	Day	6% 7% 31% 36% 14% 6%	339
	21st to end	Day	14% 8% 28% 27% 17% 6%	330
October	1st to 10th	Day	20% 8% 27% 31% 11% 3	330
	11th to 20th	Day	13% 15% 40% 22% 9% 1	330
	21st to end	Day	18% 20% 31% 23% 7% 1	363
November	1st to 10th	Day	12% 17% 41% 21% 8% 2	330
	11th to 20th	Day	11% 16% 45% 21% 7%	330
	21st to end	Day	22% 13% 35% 19% 10% 1	330
December	1st to 10th	Day	7% 13% 45% 29% 5% 1	330
	11th to 20th	Day	15% 11% 42% 25% 7%	330
	21st to end	Day	18% 11% 47% 21% 3	363
January	1st to 10th	Night	12% 11% 38% 33% 6% 1	1050
	11th to 20th	Night	11% 13% 41% 28% 6% 1	1050
	21st to end	Night	11% 10% 43% 30% 6%	1155
February	1st to 10th	Night	12% 12% 44% 27% 4	1050
	11th to 20th	Night	10% 13% 43% 30% 4	862
	21st to end	Night	10% 12% 48% 25% 4	692
March	1st to 10th	Night	13% 14% 42% 27% 3 1	772
	11th to 20th	Night	16% 12% 41% 27% 4	630
	21st to end	Night	17% 14% 43% 23% 4	693
April	1st to 10th	Night	17% 14% 41% 25% 3	630
	11th to 20th	Night	14% 16% 44% 23% 3	623
	21st to end	Night	19% 13% 33% 30% 6% 1	630
May	1st to 10th	Night	17% 10% 34% 32% 7%	630
	11th to 20th	Night	14% 9% 38% 31% 8%	621
	21st to end	Night	15% 8% 35% 32% 10%	683
June	1st to 10th	Night	7% 6% 27% 44% 13% 2	630
	11th to 20th	Night	7% 6% 38% 39% 10%	630
	21st to end	Night	7% 5% 35% 42% 12%	630
July	1st to 10th	Night	6% 3 22% 45% 24%	615
	11th to 20th	Night	3 3 20% 51% 23% 1	612
	21st to end	Night	4 2 19% 51% 23%	690
August	1st to 10th	Night	6% 3 21% 50% 19% 2	627
	11th to 20th	Night	6% 2 23% 50% 18%	624
	21st to end	Night	7% 3 25% 43% 20% 2	693
September	1st to 10th	Night	10% 3 28% 44% 15% 1	630
	11th to 20th	Night	8% 4 35% 38% 14% 1	609
	21st to end	Night	8% 7% 34% 35% 16% 1	600
October	1st to 10th	Night	16% 8% 32% 32% 12%	626
	11th to 20th	Night	13% 11% 39% 30% 7%	800
	21st to end	Night	15% 12% 32% 31% 9%	986
November	1st to 10th	Night	8% 10% 39% 37% 6%	1025
	11th to 20th	Night	10% 12% 42% 30% 6%	1050
	21st to end	Night	12% 12% 35% 31% 10%	1050
December	1st to 10th	Night	10% 11% 46% 29% 4	1050
	11th to 20th	Night	13% 10% 42% 29% 5%	1050
	21st to end	Night	15% 12% 39% 28% 5%	1155

Page generated at 2026-09-11 03:11:52. Version ac07

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