Nebraska City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nebraska City clear sky chart from 2005-11-06 to 2025-03-12.

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	11% 7% 3 7% 4 4 4 4 5% 7% 45%	108931
	Night	10% 7% 2 7% 4 4 4 3 5% 7% 48%	110281
Transparency	Day	39% 3 13% 27% 17% 2	112595
	Night	37% 3 12% 27% 19% 3	114744
Seeing	Day	14% 7% 28% 31% 17% 4	16158
	Night	14% 7% 31% 35% 12% 1	26222

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	9% 12% 4 14% 7% 5% 4 4 5% 6% 31%	4077
	11th to 20th	Day	7% 9% 4 8% 5% 6% 6% 4 5% 6% 41%	4080
	21st to end	Day	7% 11% 5% 10% 6% 5% 4 4 5% 7% 36%	4488
February	1st to 10th	Day	10% 12% 5% 8% 6% 5% 4 3 6% 7% 35%	1800
	11th to 20th	Day	10% 9% 3 7% 5% 5% 5% 3 4 8% 39%	1779
	21st to end	Day	10% 8% 3 6% 6% 4 4 3 4 7% 45%	1650
March	1st to 10th	Day	13% 8% 3 6% 4 3 3 3 4 5% 48%	3534
	11th to 20th	Day	11% 7% 2 6% 4 4 4 3 5% 6% 49%	3491
	21st to end	Day	19% 9% 4 9% 5% 4 5% 3 5% 6% 29%	3814
April	1st to 10th	Day	16% 6% 2 6% 4 4 4 3 5% 6% 45%	2154
	11th to 20th	Day	16% 6% 2 6% 5% 5% 4 3 5% 6% 41%	2331
	21st to end	Day	19% 7% 2 7% 4 4 5% 3 4 7% 39%	2470
May	1st to 10th	Day	15% 7% 3 7% 5% 5% 5% 4 5% 8% 37%	4082
	11th to 20th	Day	15% 6% 3 7% 4 4 4 4 5% 6% 43%	4082
	21st to end	Day	14% 6% 2 6% 5% 4 4 4 6% 8% 41%	4594
June	1st to 10th	Day	6% 4 2 6% 4 3 4 5% 7% 9% 50%	2660
	11th to 20th	Day	8% 5% 2 5% 4 4 4 4 7% 9% 48%	2660
	21st to end	Day	6% 5% 2 6% 5% 6% 6% 4 6% 7% 47%	2660
July	1st to 10th	Day	12% 5% 2 6% 4 4 5% 4 7% 8% 44%	4137
	11th to 20th	Day	6% 3 2 4 4 4 4 4 6% 8% 55%	4120
	21st to end	Day	4 3 2 4 3 3 4 4 6% 10% 56%	4465
August	1st to 10th	Day	6% 4 2 5% 4 4 5% 5% 8% 10% 48%	4104
	11th to 20th	Day	13% 6% 2 6% 4 4 4 4 6% 9% 43%	4041
	21st to end	Day	6% 4 2 6% 4 4 5% 4 6% 8% 50%	4414
September	1st to 10th	Day	12% 4 1 4 3 3 4 3 4 6% 55%	2223
	11th to 20th	Day	10% 5% 1 5% 4 4 4 3 5% 7% 53%	2090
	21st to end	Day	11% 4 2 4 2 2 4 2 5% 6% 57%	2090
October	1st to 10th	Day	14% 5% 2 5% 3 2 3 2 5% 6% 53%	1933
	11th to 20th	Day	12% 6% 2 5% 2 2 3 3 4 5% 58%	1900
	21st to end	Day	13% 7% 2 6% 4 3 3 3 5% 7% 48%	2090
November	1st to 10th	Day	11% 6% 2 5% 4 2 3 2 5% 5% 55%	1819
	11th to 20th	Day	11% 7% 2 7% 5% 3 3 3 4 6% 49%	1738
	21st to end	Day	12% 9% 3 6% 4 3 4 3 5% 7% 44%	1600
December	1st to 10th	Day	5% 5% 2 6% 4 5% 4 3 5% 7% 54%	2610
	11th to 20th	Day	9% 8% 2 9% 5% 4 4 3 5% 6% 43%	3008
	21st to end	Day	18% 10% 5% 14% 5% 4 3 3 4 5% 29%	4143
January	1st to 10th	Night	10% 9% 4 19% 7% 5% 4 4 4 6% 27%	5888
	11th to 20th	Night	7% 8% 3 8% 5% 5% 7% 4 6% 6% 42%	5900
	21st to end	Night	11% 12% 4 9% 4 4 4 3 4 5% 40%	6490
February	1st to 10th	Night	11% 11% 3 8% 6% 4 4 4 4 5% 40%	2600
	11th to 20th	Night	10% 9% 3 7% 4 4 4 4 6% 7% 42%	2525
	21st to end	Night	9% 7% 2 7% 4 5% 3 3 4 6% 51%	1980
March	1st to 10th	Night	11% 6% 2 5% 3 3 4 3 3 6% 53%	3539
	11th to 20th	Night	11% 7% 2 5% 2 2 3 2 4 6% 57%	3497
	21st to end	Night	18% 10% 3 8% 4 4 4 3 5% 7% 34%	3817
April	1st to 10th	Night	13% 6% 2 6% 4 3 3 3 5% 6% 47%	2025
	11th to 20th	Night	11% 8% 3 6% 4 4 4 3 5% 7% 46%	1797
	21st to end	Night	18% 7% 2 5% 4 3 3 3 4 6% 45%	1710
May	1st to 10th	Night	19% 6% 2 5% 4 4 4 3 4 5% 45%	2823
	11th to 20th	Night	14% 5% 2 5% 3 3 3 2 4 7% 50%	2823
	21st to end	Night	16% 6% 2 5% 4 3 4 3 5% 6% 45%	2971
June	1st to 10th	Night	5% 3 2 5% 4 3 4 4 7% 9% 55%	1520
	11th to 20th	Night	7% 4 1 3 3 3 4 4 8% 9% 53%	1520
	21st to end	Night	3 3 1 4 3 4 4 4 7% 8% 58%	1520
July	1st to 10th	Night	8% 5% 2 6% 4 4 4 4 5% 8% 50%	2814
	11th to 20th	Night	4 3 1 4 3 3 3 3 5% 9% 62%	2850
	21st to end	Night	4 2 1 3 4 4 4 4 7% 10% 58%	3098
August	1st to 10th	Night	3 3 1 4 3 3 4 3 5% 9% 60%	2836
	11th to 20th	Night	12% 5% 2 4 3 3 4 3 5% 7% 52%	2798
	21st to end	Night	6% 4 1 5% 3 3 3 3 5% 8% 58%	3248
September	1st to 10th	Night	9% 3 1 4 3 4 3 3 4 7% 58%	1953
	11th to 20th	Night	8% 4 1 5% 3 3 3 4 5% 7% 57%	2090
	21st to end	Night	8% 4 1 4 3 3 3 4 4 5% 60%	2090
October	1st to 10th	Night	12% 6% 1 4 3 3 3 3 6% 6% 53%	2227
	11th to 20th	Night	12% 5% 2 4 2 2 3 2 4 6% 57%	2280
	21st to end	Night	14% 6% 2 5% 3 3 4 3 4 6% 51%	2508
November	1st to 10th	Night	9% 4 2 4 3 3 3 3 6% 7% 56%	2476
	11th to 20th	Night	10% 6% 2 5% 3 4 3 3 4 7% 53%	2659
	21st to end	Night	12% 7% 2 5% 3 3 3 3 4 6% 51%	2800
December	1st to 10th	Night	5% 5% 2 5% 4 4 4 3 5% 8% 54%	4580
	11th to 20th	Night	10% 8% 3 7% 4 4 4 3 5% 7% 46%	5199
	21st to end	Night	17% 14% 5% 10% 4 3 3 3 4 5% 33%	6830

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	56% 3 10% 22% 8% 1	4078
	11th to 20th	Day	45% 2 12% 21% 17% 2	4080
	21st to end	Day	50% 2 13% 22% 12%	4488
February	1st to 10th	Day	50% 3 15% 21% 11% 1	1800
	11th to 20th	Day	46% 2 11% 25% 13% 3	1788
	21st to end	Day	41% 3 13% 26% 16% 2	1650
March	1st to 10th	Day	41% 2 10% 26% 18% 3	3534
	11th to 20th	Day	39% 2 10% 30% 19% 1	3491
	21st to end	Day	57% 2 20% 16% 5% 1	3814
April	1st to 10th	Day	42% 2 12% 29% 14% 2	2154
	11th to 20th	Day	44% 2 13% 23% 15% 2	2331
	21st to end	Day	48% 2 11% 25% 14% 1	2470
May	1st to 10th	Day	47% 2 10% 25% 13% 3	4120
	11th to 20th	Day	43% 2 10% 28% 16% 1	4086
	21st to end	Day	42% 2 12% 28% 16% 1	4607
June	1st to 10th	Day	30% 4 18% 30% 15% 2	2660
	11th to 20th	Day	33% 3 15% 31% 17% 2	2660
	21st to end	Day	35% 4 13% 31% 14% 4	2660
July	1st to 10th	Day	37% 4 15% 28% 14% 2	4073
	11th to 20th	Day	28% 4 12% 33% 20% 3	4051
	21st to end	Day	22% 5% 18% 34% 19% 3	4325
August	1st to 10th	Day	30% 4 17% 30% 18% 2	4090
	11th to 20th	Day	38% 4 15% 25% 17% 1	4080
	21st to end	Day	32% 5% 14% 28% 16% 5%	4413
September	1st to 10th	Day	31% 2 10% 30% 21% 5%	2223
	11th to 20th	Day	32% 2 11% 33% 21% 1	2090
	21st to end	Day	29% 2 8% 34% 25% 1	2090
October	1st to 10th	Day	21% 1 7% 20% 48% 3	3206
	11th to 20th	Day	21% 1 10% 32% 29% 8%	3140
	21st to end	Day	35% 2 8% 29% 23% 3	3428
November	1st to 10th	Day	33% 2 13% 30% 20% 3	1819
	11th to 20th	Day	38% 2 12% 27% 20% 1	1738
	21st to end	Day	42% 3 11% 29% 14% 1	1600
December	1st to 10th	Day	31% 4 18% 32% 16%	2610
	11th to 20th	Day	43% 2 16% 28% 10%	3005
	21st to end	Day	59% 2 12% 20% 6%	4143
January	1st to 10th	Night	60% 3 10% 17% 10%	5888
	11th to 20th	Night	44% 2 12% 24% 17% 2	5900
	21st to end	Night	49% 2 12% 19% 16% 3	6490
February	1st to 10th	Night	48% 2 12% 21% 14% 3	2600
	11th to 20th	Night	42% 3 13% 25% 15% 3	2526
	21st to end	Night	37% 2 9% 25% 22% 5%	1980
March	1st to 10th	Night	35% 2 8% 28% 23% 4	3539
	11th to 20th	Night	32% 1 8% 32% 21% 6%	3497
	21st to end	Night	52% 2 21% 19% 5% 1	3817
April	1st to 10th	Night	39% 2 9% 28% 18% 3	2025
	11th to 20th	Night	40% 2 9% 28% 17% 3	1797
	21st to end	Night	42% 2 12% 24% 18% 2	1710
May	1st to 10th	Night	44% 2 9% 24% 19% 2	2850
	11th to 20th	Night	37% 2 12% 26% 22% 2	2824
	21st to end	Night	42% 2 12% 22% 19% 3	2979
June	1st to 10th	Night	26% 5% 14% 34% 17% 4	1520
	11th to 20th	Night	26% 4 15% 31% 20% 4	1520
	21st to end	Night	24% 3 15% 32% 22% 3	1520
July	1st to 10th	Night	34% 4 13% 28% 18% 3	2769
	11th to 20th	Night	20% 4 14% 36% 23% 3	2796
	21st to end	Night	20% 6% 16% 34% 22% 2	2999
August	1st to 10th	Night	22% 3 16% 35% 21% 2	2826
	11th to 20th	Night	32% 4 14% 29% 19% 2	2825
	21st to end	Night	26% 3 17% 29% 18% 8%	3248
September	1st to 10th	Night	28% 2 10% 29% 24% 7%	1953
	11th to 20th	Night	28% 3 11% 35% 21% 3	2090
	21st to end	Night	28% 2 7% 30% 29% 4	2090
October	1st to 10th	Night	20% 2 6% 20% 48% 5%	3721
	11th to 20th	Night	22% 2 6% 30% 30% 10%	3779
	21st to end	Night	34% 3 8% 29% 24% 2	4120
November	1st to 10th	Night	28% 2 15% 27% 24% 4	2476
	11th to 20th	Night	33% 2 11% 31% 20% 3	2659
	21st to end	Night	37% 2 12% 29% 19% 2	2800
December	1st to 10th	Night	31% 4 13% 36% 16% 1	4580
	11th to 20th	Night	39% 3 15% 30% 13%	5201
	21st to end	Night	56% 2 11% 23% 7% 1	6830

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	18% 12% 34% 26% 8% 2	300
	11th to 20th	Day	19% 14% 32% 27% 8%	300
	21st to end	Day	13% 10% 42% 28% 7% 1	330
February	1st to 10th	Day	18% 13% 44% 21% 4	300
	11th to 20th	Day	16% 16% 35% 26% 7% 1	300
	21st to end	Day	11% 15% 40% 28% 6%	249
March	1st to 10th	Day	15% 12% 42% 24% 6%	300
	11th to 20th	Day	27% 9% 30% 23% 9% 1	273
	21st to end	Day	24% 17% 33% 22% 4 1	297
April	1st to 10th	Day	23% 10% 40% 22% 5%	334
	11th to 20th	Day	21% 10% 35% 24% 9% 1	529
	21st to end	Day	22% 11% 34% 20% 12% 1	650
May	1st to 10th	Day	19% 9% 33% 26% 12% 2	653
	11th to 20th	Day	19% 5% 29% 30% 15% 2	675
	21st to end	Day	20% 5% 26% 31% 16% 3	734
June	1st to 10th	Day	6% 4 21% 29% 30% 9%	680
	11th to 20th	Day	10% 3 27% 35% 20% 6%	680
	21st to end	Day	8% 5% 30% 36% 18% 4	680
July	1st to 10th	Day	10% 2 14% 32% 31% 11%	671
	11th to 20th	Day	6% 1 18% 41% 26% 8%	668
	21st to end	Day	8% 2 13% 40% 30% 7%	739
August	1st to 10th	Day	8% 2 15% 42% 28% 6%	676
	11th to 20th	Day	10% 3 16% 42% 25% 5%	665
	21st to end	Day	10% 1 18% 36% 28% 8%	682
September	1st to 10th	Day	12% 2 22% 36% 21% 7%	433
	11th to 20th	Day	7% 2 24% 37% 20% 10%	300
	21st to end	Day	16% 4 25% 34% 17% 3	300
October	1st to 10th	Day	19% 5% 23% 30% 14% 8%	300
	11th to 20th	Day	8% 15% 40% 24% 12% 1	300
	21st to end	Day	18% 13% 35% 23% 7% 4	330
November	1st to 10th	Day	18% 9% 34% 28% 8% 3	300
	11th to 20th	Day	19% 14% 37% 23% 8%	300
	21st to end	Day	21% 12% 32% 26% 9% 1	300
December	1st to 10th	Day	8% 12% 38% 31% 8% 2	300
	11th to 20th	Day	18% 13% 31% 28% 10%	300
	21st to end	Day	21% 13% 37% 24% 4 1	330
January	1st to 10th	Night	12% 10% 35% 34% 8% 1	1000
	11th to 20th	Night	15% 13% 33% 31% 8%	1000
	21st to end	Night	17% 8% 38% 31% 6%	1100
February	1st to 10th	Night	17% 11% 37% 30% 5%	1000
	11th to 20th	Night	14% 10% 40% 30% 5%	971
	21st to end	Night	13% 11% 40% 29% 6% 1	660
March	1st to 10th	Night	14% 11% 38% 30% 7%	610
	11th to 20th	Night	19% 6% 35% 33% 7%	575
	21st to end	Night	24% 8% 36% 25% 6%	627
April	1st to 10th	Night	17% 13% 38% 26% 6%	570
	11th to 20th	Night	16% 12% 36% 32% 4 1	563
	21st to end	Night	20% 6% 35% 30% 8% 1	570
May	1st to 10th	Night	18% 8% 29% 36% 9% 1	570
	11th to 20th	Night	16% 6% 28% 39% 11% 1	561
	21st to end	Night	16% 5% 26% 36% 16%	617
June	1st to 10th	Night	7% 3 22% 47% 21% 1	570
	11th to 20th	Night	9% 1 27% 45% 17% 1	570
	21st to end	Night	5% 4 28% 46% 18%	570
July	1st to 10th	Night	8% 2 12% 41% 35% 2	555
	11th to 20th	Night	4 1 16% 49% 28% 2	552
	21st to end	Night	4 1 14% 52% 28% 2	624
August	1st to 10th	Night	6% 1 14% 51% 25% 3	567
	11th to 20th	Night	9% 3 13% 49% 23% 3	564
	21st to end	Night	9% 1 19% 42% 26% 3	627
September	1st to 10th	Night	11% 3 23% 38% 22% 3	570
	11th to 20th	Night	10% 3 26% 39% 21% 2	570
	21st to end	Night	12% 3 27% 39% 18% 1	570
October	1st to 10th	Night	14% 5% 29% 35% 16% 2	707
	11th to 20th	Night	16% 8% 36% 33% 8%	760
	21st to end	Night	19% 10% 30% 33% 8%	836
November	1st to 10th	Night	11% 9% 32% 37% 10%	916
	11th to 20th	Night	14% 12% 37% 29% 8%	1000
	21st to end	Night	17% 10% 35% 29% 9%	1000
December	1st to 10th	Night	14% 11% 36% 33% 7%	1000
	11th to 20th	Night	18% 8% 33% 33% 7%	1000
	21st to end	Night	20% 11% 35% 29% 5%	1100

Page generated at 2025-03-09 07:08:49. Version ac07

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