Omaha
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Omaha clear sky chart from 2005-11-06 to 2024-11-04.

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% 42%	101140
	Night	11% 7% 3 7% 4 4 4 3 5% 7% 47%	97961
Transparency	Day	38% 7% 13% 25% 15% 2	104804
	Night	36% 6% 13% 25% 18% 3	102424
Seeing	Day	15% 9% 31% 29% 14% 3	15811
	Night	13% 9% 33% 34% 10% 1	25654

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% 6% 16% 9% 5% 4 4 5% 6% 25%	2847
	11th to 20th	Day	9% 11% 5% 10% 5% 6% 7% 4 6% 8% 29%	2850
	21st to end	Day	10% 14% 6% 16% 7% 6% 4 3 4 5% 25%	3135
February	1st to 10th	Day	9% 13% 4 10% 7% 6% 4 4 5% 7% 31%	1710
	11th to 20th	Day	10% 10% 3 9% 5% 4 4 4 5% 8% 38%	1679
	21st to end	Day	10% 8% 4 9% 5% 4 4 4 6% 6% 40%	1570
March	1st to 10th	Day	13% 10% 3 6% 4 3 4 3 3 4 48%	3404
	11th to 20th	Day	11% 7% 3 6% 4 4 4 3 4 6% 48%	3480
	21st to end	Day	21% 12% 3 10% 5% 4 4 3 6% 7% 24%	3814
April	1st to 10th	Day	16% 8% 3 6% 4 3 3 3 4 7% 43%	2156
	11th to 20th	Day	16% 9% 2 6% 4 4 4 4 5% 6% 40%	2350
	21st to end	Day	20% 7% 2 6% 4 3 5% 4 5% 7% 37%	2470
May	1st to 10th	Day	15% 8% 3 8% 5% 4 5% 4 6% 7% 34%	4082
	11th to 20th	Day	14% 8% 3 7% 4 4 4 3 5% 6% 43%	4082
	21st to end	Day	14% 6% 3 7% 4 5% 4 5% 7% 8% 39%	4662
June	1st to 10th	Day	8% 5% 2 5% 4 5% 5% 4 6% 9% 47%	2660
	11th to 20th	Day	9% 5% 2 5% 5% 3 4 4 7% 9% 46%	2660
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 6% 8% 49%	2660
July	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 7% 8% 42%	4230
	11th to 20th	Day	6% 4 2 5% 4 4 4 3 5% 7% 55%	4120
	21st to end	Day	3 3 2 5% 4 4 4 5% 7% 11% 52%	4465
August	1st to 10th	Day	6% 5% 1 6% 4 5% 6% 5% 7% 10% 45%	4104
	11th to 20th	Day	13% 6% 2 6% 5% 4 4 4 5% 8% 41%	4041
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 3 6% 8% 49%	4441
September	1st to 10th	Day	12% 5% 1 4 3 3 3 3 4 7% 55%	2225
	11th to 20th	Day	9% 6% 1 5% 3 3 3 3 5% 7% 53%	2090
	21st to end	Day	11% 4 2 5% 2 4 4 3 5% 5% 56%	2090
October	1st to 10th	Day	14% 5% 2 4 3 3 4 4 4 6% 52%	1933
	11th to 20th	Day	12% 6% 2 4 3 3 3 2 4 5% 56%	1900
	21st to end	Day	13% 7% 2 6% 4 4 3 3 5% 5% 47%	2090
November	1st to 10th	Day	10% 5% 2 5% 3 3 3 2 5% 6% 55%	1733
	11th to 20th	Day	10% 8% 2 9% 5% 4 4 4 4 6% 44%	1625
	21st to end	Day	13% 9% 4 5% 4 3 3 3 6% 8% 43%	1520
December	1st to 10th	Day	9% 9% 3 8% 5% 4 5% 3 5% 8% 42%	1520
	11th to 20th	Day	9% 11% 4 9% 6% 5% 5% 4 6% 7% 35%	1918
	21st to end	Day	15% 11% 5% 16% 6% 5% 4 4 4 5% 23%	2824
January	1st to 10th	Night	8% 10% 4 20% 9% 5% 3 3 5% 5% 26%	4108
	11th to 20th	Night	8% 11% 4 7% 4 5% 8% 4 8% 6% 33%	4120
	21st to end	Night	11% 14% 5% 13% 5% 5% 4 3 5% 6% 29%	4532
February	1st to 10th	Night	11% 10% 4 10% 5% 5% 4 3 5% 6% 37%	2470
	11th to 20th	Night	9% 9% 4 7% 4 4 4 4 6% 7% 42%	2403
	21st to end	Night	9% 8% 4 7% 4 4 4 3 5% 5% 48%	1884
March	1st to 10th	Night	12% 7% 2 5% 3 3 4 2 4 5% 52%	3451
	11th to 20th	Night	11% 7% 2 4 2 3 3 2 4 5% 56%	3480
	21st to end	Night	18% 10% 3 9% 4 4 4 3 5% 8% 31%	3817
April	1st to 10th	Night	13% 8% 2 5% 4 3 4 3 5% 6% 46%	2024
	11th to 20th	Night	12% 8% 2 6% 3 4 4 3 4 6% 47%	1778
	21st to end	Night	16% 8% 2 6% 3 4 3 3 4 6% 44%	1710
May	1st to 10th	Night	18% 6% 2 5% 3 4 4 3 5% 6% 43%	2823
	11th to 20th	Night	12% 6% 2 5% 3 3 3 3 5% 8% 49%	2823
	21st to end	Night	15% 7% 2 6% 4 3 4 3 5% 6% 44%	2900
June	1st to 10th	Night	5% 4 1 5% 3 3 5% 4 6% 8% 54%	1520
	11th to 20th	Night	7% 4 2 4 3 3 5% 5% 8% 10% 49%	1520
	21st to end	Night	4 3 2 4 3 5% 5% 4 5% 8% 56%	1520
July	1st to 10th	Night	7% 5% 2 5% 4 4 3 4 6% 9% 51%	2721
	11th to 20th	Night	5% 3 1 3 2 2 3 3 5% 8% 64%	2850
	21st to end	Night	3 3 1 4 4 4 4 3 6% 10% 58%	3098
August	1st to 10th	Night	3 3 2 5% 3 3 4 3 7% 9% 58%	2836
	11th to 20th	Night	10% 6% 2 5% 4 4 4 4 5% 7% 50%	2798
	21st to end	Night	7% 4 1 4 3 3 4 4 6% 8% 56%	3223
September	1st to 10th	Night	9% 3 1 4 3 3 3 3 4 7% 59%	1952
	11th to 20th	Night	9% 4 1 3 3 3 3 3 6% 7% 58%	2090
	21st to end	Night	10% 5% 2 4 2 3 3 3 4 6% 60%	2090
October	1st to 10th	Night	13% 5% 1 4 3 3 4 3 4 7% 53%	2226
	11th to 20th	Night	13% 6% 2 4 4 2 3 3 4 5% 55%	2280
	21st to end	Night	13% 7% 2 5% 3 4 3 3 5% 5% 51%	2508
November	1st to 10th	Night	9% 5% 2 4 2 3 4 3 5% 7% 57%	2415
	11th to 20th	Night	10% 7% 2 6% 4 4 3 2 5% 7% 52%	2553
	21st to end	Night	12% 8% 3 5% 4 3 3 2 5% 6% 50%	2660
December	1st to 10th	Night	8% 9% 3 7% 5% 4 4 3 5% 7% 43%	2660
	11th to 20th	Night	9% 10% 3 7% 4 4 4 3 5% 6% 46%	3279
	21st to end	Night	18% 13% 6% 12% 4 3 3 3 4 4 30%	4839

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	58% 6% 13% 15% 6% 1	2848
	11th to 20th	Day	52% 6% 13% 22% 7%	2850
	21st to end	Day	59% 8% 12% 14% 7%	3135
February	1st to 10th	Day	52% 7% 14% 17% 10% 1	1710
	11th to 20th	Day	44% 6% 12% 24% 13% 2	1688
	21st to end	Day	43% 7% 11% 22% 14% 3	1570
March	1st to 10th	Day	41% 5% 9% 26% 17% 2	3404
	11th to 20th	Day	37% 6% 12% 28% 16% 2	3480
	21st to end	Day	57% 10% 17% 11% 4	3814
April	1st to 10th	Day	43% 5% 12% 26% 12% 1	2156
	11th to 20th	Day	43% 7% 13% 22% 13% 3	2350
	21st to end	Day	45% 7% 11% 23% 12% 1	2470
May	1st to 10th	Day	44% 10% 14% 19% 12% 2	4120
	11th to 20th	Day	40% 7% 11% 24% 17% 1	4086
	21st to end	Day	38% 11% 13% 22% 15% 1	4675
June	1st to 10th	Day	31% 9% 16% 28% 13% 3	2660
	11th to 20th	Day	32% 8% 14% 30% 15% 1	2660
	21st to end	Day	31% 8% 15% 28% 14% 3	2660
July	1st to 10th	Day	37% 7% 14% 28% 12% 1	4166
	11th to 20th	Day	27% 6% 13% 32% 19% 3	4051
	21st to end	Day	22% 8% 19% 29% 20% 1	4325
August	1st to 10th	Day	31% 8% 15% 28% 16% 1	4090
	11th to 20th	Day	40% 7% 13% 26% 14% 1	4080
	21st to end	Day	32% 7% 15% 26% 16% 4	4440
September	1st to 10th	Day	30% 5% 12% 29% 19% 5%	2225
	11th to 20th	Day	30% 6% 12% 33% 18% 1	2090
	21st to end	Day	29% 5% 10% 31% 24% 1	2090
October	1st to 10th	Day	20% 3 7% 21% 46% 2	3206
	11th to 20th	Day	21% 3 12% 30% 26% 7%	3140
	21st to end	Day	36% 4 10% 27% 20% 3	3428
November	1st to 10th	Day	31% 4 15% 28% 20% 3	1733
	11th to 20th	Day	40% 7% 12% 24% 17% 1	1625
	21st to end	Day	41% 4 12% 30% 12% 1	1520
December	1st to 10th	Day	40% 6% 17% 24% 12% 1	1520
	11th to 20th	Day	46% 6% 17% 26% 5%	1915
	21st to end	Day	61% 7% 10% 16% 6%	2824
January	1st to 10th	Night	57% 7% 12% 15% 9% 1	4108
	11th to 20th	Night	47% 6% 15% 22% 10% 1	4120
	21st to end	Night	53% 7% 15% 15% 8% 1	4532
February	1st to 10th	Night	47% 6% 13% 20% 12% 2	2470
	11th to 20th	Night	39% 7% 14% 22% 15% 2	2404
	21st to end	Night	37% 5% 11% 23% 20% 3	1884
March	1st to 10th	Night	34% 6% 10% 27% 21% 3	3451
	11th to 20th	Night	31% 6% 8% 32% 18% 5%	3480
	21st to end	Night	49% 10% 20% 15% 5% 1	3817
April	1st to 10th	Night	37% 7% 11% 26% 17% 3	2024
	11th to 20th	Night	38% 5% 11% 25% 18% 3	1778
	21st to end	Night	40% 7% 13% 23% 16% 1	1710
May	1st to 10th	Night	39% 7% 13% 23% 16% 2	2850
	11th to 20th	Night	33% 8% 11% 25% 20% 2	2824
	21st to end	Night	39% 8% 12% 20% 18% 3	2908
June	1st to 10th	Night	25% 9% 15% 33% 15% 4	1520
	11th to 20th	Night	26% 9% 15% 26% 20% 4	1520
	21st to end	Night	25% 6% 15% 32% 19% 3	1520
July	1st to 10th	Night	29% 7% 15% 31% 16% 2	2676
	11th to 20th	Night	19% 5% 16% 35% 23% 3	2796
	21st to end	Night	20% 8% 16% 33% 22% 1	2999
August	1st to 10th	Night	21% 7% 14% 35% 20% 2	2826
	11th to 20th	Night	34% 6% 13% 27% 19% 2	2825
	21st to end	Night	27% 6% 16% 26% 17% 8%	3223
September	1st to 10th	Night	25% 6% 12% 29% 23% 6%	1952
	11th to 20th	Night	25% 5% 13% 35% 20% 3	2090
	21st to end	Night	26% 5% 9% 29% 27% 4	2090
October	1st to 10th	Night	20% 4 7% 17% 49% 4	3720
	11th to 20th	Night	23% 3 8% 28% 30% 8%	3779
	21st to end	Night	34% 3 10% 29% 22% 1	4120
November	1st to 10th	Night	27% 5% 15% 25% 23% 4	2415
	11th to 20th	Night	33% 5% 13% 30% 17% 2	2553
	21st to end	Night	36% 4 12% 29% 18% 2	2660
December	1st to 10th	Night	40% 6% 13% 28% 12% 1	2660
	11th to 20th	Night	39% 5% 16% 32% 8%	3281
	21st to end	Night	58% 5% 10% 19% 7% 1	4839

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	20% 12% 35% 23% 8% 2	270
	11th to 20th	Day	22% 12% 36% 22% 7% 1	270
	21st to end	Day	15% 12% 43% 20% 8% 2	297
February	1st to 10th	Day	16% 17% 45% 19% 3	270
	11th to 20th	Day	18% 16% 38% 21% 6% 1	270
	21st to end	Day	15% 20% 40% 22% 4	225
March	1st to 10th	Day	18% 14% 43% 20% 5%	270
	11th to 20th	Day	27% 11% 36% 19% 7% 1	270
	21st to end	Day	33% 16% 34% 14% 2 1	297
April	1st to 10th	Day	25% 16% 38% 18% 3	336
	11th to 20th	Day	20% 16% 36% 21% 7%	548
	21st to end	Day	23% 17% 30% 21% 7% 2	650
May	1st to 10th	Day	20% 13% 33% 24% 8% 2	653
	11th to 20th	Day	18% 9% 32% 27% 12% 2	675
	21st to end	Day	19% 7% 31% 27% 14% 2	734
June	1st to 10th	Day	6% 6% 23% 36% 24% 4	680
	11th to 20th	Day	10% 6% 31% 34% 16% 3	680
	21st to end	Day	9% 8% 34% 34% 13% 3	680
July	1st to 10th	Day	11% 4 15% 32% 28% 9%	671
	11th to 20th	Day	6% 4 28% 35% 21% 7%	668
	21st to end	Day	6% 2 20% 42% 25% 4	739
August	1st to 10th	Day	8% 2 21% 43% 22% 4	676
	11th to 20th	Day	8% 5% 19% 39% 25% 3	665
	21st to end	Day	10% 2 22% 39% 22% 5%	696
September	1st to 10th	Day	12% 3 28% 34% 18% 4	435
	11th to 20th	Day	7% 4 32% 35% 18% 5%	300
	21st to end	Day	14% 10% 30% 29% 14% 2	300
October	1st to 10th	Day	20% 6% 29% 26% 13% 5%	300
	11th to 20th	Day	12% 16% 41% 20% 8% 1	300
	21st to end	Day	19% 15% 37% 19% 9% 2	330
November	1st to 10th	Day	16% 11% 36% 25% 9% 1	279
	11th to 20th	Day	15% 14% 43% 21% 7%	270
	21st to end	Day	22% 11% 34% 23% 7% 1	270
December	1st to 10th	Day	9% 12% 41% 31% 5% 2	270
	11th to 20th	Day	14% 15% 33% 28% 9% 1	270
	21st to end	Day	21% 15% 40% 21% 3	297
January	1st to 10th	Night	12% 12% 36% 32% 8% 1	950
	11th to 20th	Night	15% 14% 35% 30% 7%	950
	21st to end	Night	17% 9% 38% 30% 6%	1045
February	1st to 10th	Night	16% 11% 40% 29% 4	950
	11th to 20th	Night	12% 11% 42% 30% 5%	929
	21st to end	Night	14% 11% 44% 25% 5%	628
March	1st to 10th	Night	14% 13% 39% 27% 6% 1	591
	11th to 20th	Night	19% 8% 37% 29% 7%	570
	21st to end	Night	21% 14% 37% 22% 4	627
April	1st to 10th	Night	15% 17% 41% 22% 4	570
	11th to 20th	Night	15% 14% 40% 28% 4 1	563
	21st to end	Night	19% 11% 34% 27% 7% 1	570
May	1st to 10th	Night	18% 11% 32% 32% 8%	570
	11th to 20th	Night	16% 9% 30% 35% 10% 1	561
	21st to end	Night	17% 7% 30% 32% 13%	617
June	1st to 10th	Night	7% 3 26% 47% 16%	570
	11th to 20th	Night	9% 4 32% 41% 13% 1	570
	21st to end	Night	5% 4 32% 45% 13% 1	570
July	1st to 10th	Night	7% 2 18% 44% 27% 2	555
	11th to 20th	Night	4 2 20% 50% 24% 1	552
	21st to end	Night	4 2 16% 53% 24% 1	624
August	1st to 10th	Night	6% 2 18% 49% 23% 2	567
	11th to 20th	Night	7% 3 19% 47% 24%	564
	21st to end	Night	9% 3 21% 41% 23% 3	627
September	1st to 10th	Night	9% 4 24% 41% 21% 2	570
	11th to 20th	Night	10% 2 30% 39% 17% 1	570
	21st to end	Night	12% 5% 32% 34% 16% 1	570
October	1st to 10th	Night	14% 7% 33% 32% 12% 2	706
	11th to 20th	Night	15% 11% 34% 33% 7%	760
	21st to end	Night	18% 11% 31% 31% 9%	836
November	1st to 10th	Night	11% 10% 33% 36% 9% 1	907
	11th to 20th	Night	14% 12% 38% 30% 7%	950
	21st to end	Night	16% 10% 35% 29% 9%	950
December	1st to 10th	Night	13% 12% 38% 31% 6%	950
	11th to 20th	Night	17% 9% 34% 33% 6% 1	950
	21st to end	Night	20% 13% 33% 29% 4	1045

Page generated at 2024-11-01 21:47:38. Version ac07

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