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 2025-05-11.

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% 49%	118471
	Night	8% 6% 2 6% 4 4 4 3 5% 7% 51%	119213
Transparency	Day	34% 6% 13% 25% 18% 3	118228
	Night	31% 6% 13% 26% 20% 4	119046
Seeing	Day	13% 10% 32% 30% 13% 2	16396
	Night	11% 9% 36% 33% 9%	26422

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% 13% 4 10% 6% 5% 4 3 5% 5% 36%	3638
	11th to 20th	Day	4 9% 4 9% 5% 5% 4 4 5% 6% 45%	4035
	21st to end	Day	5% 6% 4 12% 5% 4 4 3 4 6% 47%	4488
February	1st to 10th	Day	9% 11% 4 8% 6% 4 5% 4 6% 7% 38%	1800
	11th to 20th	Day	6% 9% 4 8% 4 3 5% 4 5% 7% 46%	1929
	21st to end	Day	8% 8% 2 6% 4 4 3 4 5% 6% 51%	1650
March	1st to 10th	Day	12% 8% 3 5% 3 2 3 2 3 4 56%	4649
	11th to 20th	Day	10% 7% 2 5% 3 3 3 3 4 6% 54%	4980
	21st to end	Day	13% 10% 3 8% 4 4 4 4 5% 7% 38%	5464
April	1st to 10th	Day	11% 8% 2 5% 4 4 3 3 5% 7% 48%	2270
	11th to 20th	Day	13% 9% 1 6% 4 4 4 3 5% 7% 44%	2516
	21st to end	Day	18% 7% 2 6% 5% 4 5% 2 5% 6% 40%	2600
May	1st to 10th	Day	13% 7% 2 6% 3 4 4 4 6% 8% 42%	4250
	11th to 20th	Day	13% 7% 2 6% 4 4 4 3 5% 6% 47%	4083
	21st to end	Day	13% 7% 2 6% 4 4 4 4 5% 7% 42%	4489
June	1st to 10th	Day	6% 4 1 4 4 4 4 5% 6% 9% 54%	2474
	11th to 20th	Day	8% 5% 2 4 5% 3 4 4 6% 7% 51%	2660
	21st to end	Day	6% 4 1 4 4 4 5% 4 7% 10% 52%	2660
July	1st to 10th	Day	10% 6% 2 6% 4 3 4 3 5% 8% 47%	4430
	11th to 20th	Day	5% 5% 2 5% 4 5% 5% 4 6% 8% 51%	4258
	21st to end	Day	4 4 2 5% 4 4 4 4 7% 9% 54%	4466
August	1st to 10th	Day	7% 5% 2 7% 5% 4 5% 4 6% 9% 45%	4103
	11th to 20th	Day	12% 6% 2 6% 4 4 4 3 6% 8% 43%	4041
	21st to end	Day	5% 4 2 5% 4 4 4 3 5% 7% 57%	4441
September	1st to 10th	Day	11% 5% 2 5% 4 3 3 3 4 6% 55%	2142
	11th to 20th	Day	8% 4 2 5% 3 4 3 2 5% 7% 57%	2090
	21st to end	Day	8% 4 1 3 2 3 3 2 5% 6% 60%	2090
October	1st to 10th	Day	9% 3 1 3 2 2 2 2 3 4 69%	3396
	11th to 20th	Day	6% 4 1 3 3 2 3 3 4 6% 65%	3140
	21st to end	Day	10% 5% 2 4 3 3 3 3 5% 6% 56%	3255
November	1st to 10th	Day	8% 5% 2 5% 3 4 3 3 6% 7% 55%	1763
	11th to 20th	Day	7% 6% 2 5% 4 3 3 2 4 6% 57%	1800
	21st to end	Day	10% 8% 2 6% 3 3 4 3 5% 7% 50%	1800
December	1st to 10th	Day	4 5% 2 5% 4 3 4 4 5% 6% 57%	2940
	11th to 20th	Day	5% 8% 3 7% 5% 4 4 4 5% 6% 48%	3391
	21st to end	Day	13% 10% 3 11% 5% 4 3 3 5% 6% 37%	4290
January	1st to 10th	Night	7% 12% 4 12% 6% 4 4 4 7% 6% 34%	6327
	11th to 20th	Night	4 7% 2 6% 5% 5% 5% 4 6% 6% 50%	5924
	21st to end	Night	6% 9% 4 11% 4 4 4 4 4 5% 45%	6490
February	1st to 10th	Night	9% 10% 4 8% 5% 4 4 4 5% 5% 43%	2600
	11th to 20th	Night	6% 9% 3 7% 5% 5% 4 5% 5% 6% 45%	2374
	21st to end	Night	6% 7% 2 6% 4 3 4 3 5% 6% 53%	1980
March	1st to 10th	Night	10% 5% 2 5% 3 4 3 3 4 5% 55%	5218
	11th to 20th	Night	9% 5% 2 4 3 3 3 2 4 5% 59%	4980
	21st to end	Night	12% 9% 3 6% 4 4 5% 4 6% 7% 40%	5467
April	1st to 10th	Night	11% 7% 2 5% 4 3 4 3 5% 7% 48%	2126
	11th to 20th	Night	11% 7% 2 5% 4 4 4 4 6% 9% 45%	1830
	21st to end	Night	15% 6% 2 5% 3 3 4 3 5% 7% 48%	1800
May	1st to 10th	Night	19% 7% 2 4 3 3 3 3 5% 6% 45%	2940
	11th to 20th	Night	9% 6% 3 6% 4 4 4 4 5% 7% 48%	2828
	21st to end	Night	13% 6% 2 6% 4 4 4 3 6% 10% 40%	3098
June	1st to 10th	Night	5% 4 2 4 4 3 4 4 7% 10% 53%	1701
	11th to 20th	Night	7% 4 2 4 3 4 3 4 6% 8% 54%	1520
	21st to end	Night	3 4 2 4 4 3 3 4 7% 9% 58%	1520
July	1st to 10th	Night	9% 5% 2 5% 3 3 4 4 6% 7% 54%	2540
	11th to 20th	Night	5% 3 1 4 3 3 5% 4 8% 10% 54%	2708
	21st to end	Night	3 3 1 3 3 3 3 3 6% 10% 61%	3097
August	1st to 10th	Night	4 3 2 5% 3 4 4 4 7% 11% 52%	2836
	11th to 20th	Night	10% 5% 2 6% 4 3 3 3 6% 9% 49%	2798
	21st to end	Night	4 3 1 4 4 4 4 4 5% 11% 56%	3222
September	1st to 10th	Night	9% 2 2 4 2 3 3 3 4 6% 64%	2038
	11th to 20th	Night	7% 3 2 5% 4 3 4 2 4 8% 58%	2090
	21st to end	Night	7% 4 2 3 4 3 4 3 5% 6% 60%	2090
October	1st to 10th	Night	9% 2 1 2 2 2 2 2 4 5% 69%	3530
	11th to 20th	Night	6% 3 1 3 3 3 3 3 4 6% 66%	3779
	21st to end	Night	9% 4 2 4 3 3 2 3 4 7% 59%	4295
November	1st to 10th	Night	6% 4 2 3 2 3 3 3 5% 7% 61%	2535
	11th to 20th	Night	7% 5% 2 4 4 3 3 3 5% 7% 57%	2600
	21st to end	Night	8% 6% 2 4 3 3 3 3 4 7% 56%	2600
December	1st to 10th	Night	3 5% 1 3 3 3 4 3 5% 7% 62%	4250
	11th to 20th	Night	7% 4 2 5% 4 4 4 4 6% 8% 51%	4816
	21st to end	Night	13% 11% 3 10% 4 4 4 3 4 6% 38%	6666

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	48% 6% 12% 21% 11% 1	3639
	11th to 20th	Day	39% 6% 14% 19% 19% 3	4035
	21st to end	Day	39% 5% 13% 26% 14% 3	4488
February	1st to 10th	Day	44% 7% 16% 21% 10% 2	1800
	11th to 20th	Day	38% 5% 16% 23% 15% 4	1939
	21st to end	Day	33% 6% 11% 27% 17% 5%	1650
March	1st to 10th	Day	33% 4 8% 23% 24% 7%	4649
	11th to 20th	Day	31% 4 9% 23% 25% 7%	4980
	21st to end	Day	43% 8% 20% 21% 6% 2	5464
April	1st to 10th	Day	35% 6% 15% 26% 16% 2	2270
	11th to 20th	Day	38% 6% 14% 23% 15% 3	2519
	21st to end	Day	43% 7% 12% 23% 14% 1	2600
May	1st to 10th	Day	35% 9% 15% 22% 15% 4	4250
	11th to 20th	Day	36% 9% 12% 27% 16% 1	4087
	21st to end	Day	38% 9% 12% 27% 12% 1	4489
June	1st to 10th	Day	25% 9% 18% 32% 15% 2	2474
	11th to 20th	Day	30% 8% 14% 28% 17% 3	2660
	21st to end	Day	25% 9% 16% 29% 18% 4	2660
July	1st to 10th	Day	34% 5% 12% 28% 20% 2	4361
	11th to 20th	Day	29% 8% 14% 28% 19% 3	4184
	21st to end	Day	24% 8% 16% 25% 22% 6%	4325
August	1st to 10th	Day	33% 8% 15% 24% 15% 4	4090
	11th to 20th	Day	38% 6% 15% 22% 17% 1	4080
	21st to end	Day	27% 6% 14% 24% 22% 7%	4440
September	1st to 10th	Day	31% 6% 12% 24% 21% 7%	2142
	11th to 20th	Day	28% 6% 12% 29% 23% 3	2090
	21st to end	Day	25% 5% 10% 32% 26% 2	2090
October	1st to 10th	Day	21% 3 5% 21% 43% 7%	3396
	11th to 20th	Day	21% 3 11% 35% 21% 9%	3140
	21st to end	Day	29% 3 10% 30% 24% 3	3255
November	1st to 10th	Day	28% 5% 15% 28% 21% 3	1763
	11th to 20th	Day	30% 5% 11% 26% 25% 4	1800
	21st to end	Day	35% 4 13% 26% 18% 3	1800
December	1st to 10th	Day	28% 5% 13% 32% 20% 3	2940
	11th to 20th	Day	35% 5% 19% 27% 13% 1	3389
	21st to end	Day	48% 5% 10% 25% 11% 1	4290
January	1st to 10th	Night	47% 6% 11% 21% 14% 1	6327
	11th to 20th	Night	32% 5% 14% 25% 22% 2	5924
	21st to end	Night	40% 6% 10% 21% 20% 4	6490
February	1st to 10th	Night	42% 7% 12% 23% 13% 3	2600
	11th to 20th	Night	37% 7% 14% 23% 15% 3	2374
	21st to end	Night	31% 4 13% 22% 23% 8%	1980
March	1st to 10th	Night	30% 4 8% 27% 26% 6%	5218
	11th to 20th	Night	27% 4 7% 20% 32% 10%	4980
	21st to end	Night	40% 8% 19% 24% 7% 1	5467
April	1st to 10th	Night	35% 6% 14% 24% 19% 2	2126
	11th to 20th	Night	35% 6% 15% 26% 15% 3	1830
	21st to end	Night	35% 8% 12% 26% 17% 2	1800
May	1st to 10th	Night	39% 6% 12% 26% 15% 3	2940
	11th to 20th	Night	33% 9% 14% 25% 19%	2829
	21st to end	Night	35% 12% 16% 22% 14% 1	3099
June	1st to 10th	Night	23% 11% 18% 29% 17% 2	1701
	11th to 20th	Night	27% 7% 15% 27% 18% 6%	1520
	21st to end	Night	21% 7% 18% 30% 21% 4	1520
July	1st to 10th	Night	29% 6% 14% 31% 18% 3	2500
	11th to 20th	Night	23% 6% 16% 32% 19% 3	2659
	21st to end	Night	17% 7% 18% 27% 25% 7%	2999
August	1st to 10th	Night	24% 7% 18% 27% 19% 5%	2826
	11th to 20th	Night	32% 6% 18% 27% 15% 1	2825
	21st to end	Night	23% 6% 16% 28% 17% 9%	3222
September	1st to 10th	Night	22% 5% 10% 28% 25% 10%	2038
	11th to 20th	Night	25% 5% 11% 30% 24% 5%	2090
	21st to end	Night	25% 5% 10% 27% 29% 4	2090
October	1st to 10th	Night	19% 4 7% 17% 45% 8%	3530
	11th to 20th	Night	21% 4 10% 29% 26% 10%	3779
	21st to end	Night	26% 3 10% 29% 27% 4	4295
November	1st to 10th	Night	22% 5% 13% 29% 25% 6%	2535
	11th to 20th	Night	28% 4 11% 29% 24% 5%	2600
	21st to end	Night	29% 4 13% 28% 23% 3	2600
December	1st to 10th	Night	22% 4 16% 36% 20% 2	4250
	11th to 20th	Night	30% 4 15% 33% 16% 1	4817
	21st to end	Night	46% 5% 11% 25% 11% 1	6666

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% 24% 8% 1	300
	11th to 20th	Day	15% 17% 34% 26% 7% 1	300
	21st to end	Day	13% 11% 46% 22% 7% 1	330
February	1st to 10th	Day	15% 15% 46% 20% 5%	300
	11th to 20th	Day	12% 10% 47% 24% 5% 1	300
	21st to end	Day	12% 18% 47% 17% 4	249
March	1st to 10th	Day	14% 14% 45% 23% 3 1	300
	11th to 20th	Day	21% 12% 37% 20% 9%	300
	21st to end	Day	25% 16% 38% 17% 4	330
April	1st to 10th	Day	17% 22% 39% 18% 4	370
	11th to 20th	Day	19% 16% 37% 24% 5%	637
	21st to end	Day	22% 17% 31% 20% 8% 2	700
May	1st to 10th	Day	15% 13% 33% 27% 11% 2	703
	11th to 20th	Day	17% 11% 32% 26% 11% 3	676
	21st to end	Day	15% 10% 32% 29% 12% 1	734
June	1st to 10th	Day	5% 7% 27% 36% 20% 5%	680
	11th to 20th	Day	10% 7% 35% 32% 14% 2	680
	21st to end	Day	7% 8% 33% 34% 17% 2	680
July	1st to 10th	Day	9% 4 19% 39% 25% 5%	671
	11th to 20th	Day	5% 2 20% 45% 23% 5%	668
	21st to end	Day	6% 3 20% 40% 27% 4	739
August	1st to 10th	Day	8% 3 19% 46% 22% 3	676
	11th to 20th	Day	7% 5% 20% 43% 22% 2	665
	21st to end	Day	9% 3 23% 39% 23% 4	696
September	1st to 10th	Day	14% 4 27% 37% 14% 4	352
	11th to 20th	Day	6% 6% 31% 38% 14% 5%	300
	21st to end	Day	14% 9% 29% 27% 16% 5%	300
October	1st to 10th	Day	21% 8% 25% 32% 10% 4	300
	11th to 20th	Day	12% 14% 40% 23% 10% 1	300
	21st to end	Day	17% 18% 32% 24% 8% 1	330
November	1st to 10th	Day	12% 17% 39% 21% 8% 2	300
	11th to 20th	Day	11% 18% 45% 20% 7%	300
	21st to end	Day	20% 13% 36% 19% 10% 1	300
December	1st to 10th	Day	7% 12% 44% 31% 6% 1	300
	11th to 20th	Day	15% 10% 43% 26% 6%	300
	21st to end	Day	18% 12% 47% 20% 3	330
January	1st to 10th	Night	12% 12% 37% 33% 6% 1	1000
	11th to 20th	Night	11% 12% 41% 29% 6% 1	1000
	21st to end	Night	11% 9% 43% 30% 7%	1100
February	1st to 10th	Night	13% 12% 44% 27% 4	1000
	11th to 20th	Night	10% 12% 43% 30% 4	820
	21st to end	Night	10% 13% 48% 25% 5%	660
March	1st to 10th	Night	12% 14% 42% 28% 3 1	735
	11th to 20th	Night	16% 11% 41% 27% 5% 1	600
	21st to end	Night	17% 14% 42% 23% 4	660
April	1st to 10th	Night	17% 14% 41% 26% 3	600
	11th to 20th	Night	15% 14% 44% 23% 3	593
	21st to end	Night	18% 13% 32% 30% 6% 1	600
May	1st to 10th	Night	18% 10% 33% 31% 8%	600
	11th to 20th	Night	14% 8% 38% 32% 8%	563
	21st to end	Night	14% 8% 35% 31% 11%	617
June	1st to 10th	Night	7% 6% 27% 44% 14% 2	570
	11th to 20th	Night	8% 5% 38% 39% 10%	570
	21st to end	Night	5% 5% 34% 44% 13%	570
July	1st to 10th	Night	6% 3 21% 45% 24% 1	555
	11th to 20th	Night	3 2 21% 53% 21% 1	552
	21st to end	Night	4 2 19% 51% 24%	624
August	1st to 10th	Night	6% 2 20% 50% 20% 2	567
	11th to 20th	Night	7% 2 24% 50% 17%	564
	21st to end	Night	7% 3 26% 42% 20% 2	627
September	1st to 10th	Night	10% 2 28% 43% 16% 1	570
	11th to 20th	Night	8% 4 34% 38% 15% 1	570
	21st to end	Night	8% 7% 35% 34% 15% 1	570
October	1st to 10th	Night	16% 8% 32% 32% 12%	594
	11th to 20th	Night	13% 11% 39% 31% 7%	760
	21st to end	Night	14% 12% 33% 31% 10%	936
November	1st to 10th	Night	9% 10% 37% 38% 6% 1	975
	11th to 20th	Night	10% 12% 41% 30% 6%	1000
	21st to end	Night	11% 11% 36% 31% 10%	1000
December	1st to 10th	Night	9% 11% 45% 29% 5%	1000
	11th to 20th	Night	13% 10% 42% 30% 5%	1000
	21st to end	Night	16% 13% 39% 28% 5%	1100

Page generated at 2025-05-08 08:33:54. Version ac07

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