Council Bluffs Recreational Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Council Bluffs Recreational Area clear sky chart from 2005-11-06 to 2026-10-14.

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	12% 7% 3 6% 4 4 4 4 5% 7% 43%	149085
	Night	12% 8% 3 7% 4 4 4 3 5% 6% 44%	142983
Transparency	Day	38% 6% 11% 25% 17% 3	152681
	Night	38% 6% 11% 24% 18% 3	147467
Seeing	Day	18% 14% 29% 24% 12% 3	18244
	Night	18% 14% 30% 25% 11% 1	27947

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	12% 11% 4 10% 4 4 4 2 4 6% 40%	4733
	11th to 20th	Day	8% 9% 3 7% 4 4 4 3 4 6% 48%	5310
	21st to end	Day	15% 8% 4 8% 4 3 3 3 4 5% 42%	5812
February	1st to 10th	Day	14% 11% 3 8% 5% 4 4 3 5% 6% 36%	1890
	11th to 20th	Day	15% 10% 3 8% 4 4 4 4 5% 7% 37%	2018
	21st to end	Day	13% 11% 2 7% 3 4 4 4 5% 6% 40%	1730
March	1st to 10th	Day	15% 12% 3 6% 3 3 3 2 4 4 45%	4764
	11th to 20th	Day	10% 7% 2 4 3 3 4 3 5% 7% 53%	5090
	21st to end	Day	12% 9% 3 6% 5% 5% 4 4 6% 7% 39%	5814
April	1st to 10th	Day	12% 6% 2 7% 4 4 4 3 6% 8% 44%	2520
	11th to 20th	Day	17% 8% 3 6% 4 4 4 3 5% 6% 40%	2494
	21st to end	Day	18% 8% 3 6% 5% 4 4 3 5% 7% 37%	2520
May	1st to 10th	Day	14% 7% 3 7% 5% 5% 5% 4 7% 8% 34%	7021
	11th to 20th	Day	16% 7% 3 7% 5% 4 5% 4 6% 7% 37%	8073
	21st to end	Day	20% 9% 3 7% 4 4 5% 4 5% 6% 33%	9047
June	1st to 10th	Day	10% 5% 2 6% 4 5% 5% 4 6% 9% 43%	2940
	11th to 20th	Day	6% 5% 1 5% 5% 4 5% 4 7% 9% 47%	2940
	21st to end	Day	6% 4 2 5% 5% 6% 5% 5% 7% 10% 47%	2940
July	1st to 10th	Day	9% 5% 2 6% 5% 4 6% 4 6% 9% 43%	8280
	11th to 20th	Day	5% 5% 2 7% 5% 6% 6% 5% 7% 10% 43%	8162
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 5% 8% 11% 41%	8337
August	1st to 10th	Day	8% 4 2 5% 3 4 4 4 7% 9% 50%	5996
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 6% 9% 48%	5486
	21st to end	Day	6% 4 2 5% 3 4 4 4 6% 8% 55%	6080
September	1st to 10th	Day	12% 5% 2 4 3 3 4 3 6% 7% 50%	2520
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 3 6% 8% 48%	2517
	21st to end	Day	11% 5% 3 5% 3 4 5% 3 5% 7% 49%	2264
October	1st to 10th	Day	8% 5% 2 5% 3 3 3 3 4 7% 57%	2100
	11th to 20th	Day	13% 6% 2 4 3 3 3 2 3 5% 55%	2030
	21st to end	Day	18% 8% 2 6% 3 3 3 2 4 5% 47%	2200
November	1st to 10th	Day	11% 6% 3 5% 3 3 4 3 4 5% 54%	1897
	11th to 20th	Day	12% 9% 3 6% 3 3 4 3 4 6% 47%	1890
	21st to end	Day	15% 10% 3 6% 4 3 4 3 4 4 43%	1822
December	1st to 10th	Day	10% 11% 2 6% 3 3 3 2 4 6% 50%	2690
	11th to 20th	Day	13% 11% 5% 8% 4 3 3 3 4 6% 40%	3088
	21st to end	Day	18% 20% 6% 8% 4 3 3 3 4 4 27%	4070
January	1st to 10th	Night	13% 11% 5% 11% 5% 4 3 3 4 4 37%	8172
	11th to 20th	Night	9% 9% 4 11% 4 4 4 3 3 5% 45%	7680
	21st to end	Night	15% 11% 4 8% 5% 4 3 3 4 5% 39%	8402
February	1st to 10th	Night	16% 11% 4 8% 4 4 3 3 5% 5% 38%	2730
	11th to 20th	Night	14% 9% 3 8% 4 3 3 2 4 6% 42%	2486
	21st to end	Night	15% 7% 4 8% 5% 3 4 3 3 5% 42%	2076
March	1st to 10th	Night	16% 14% 3 6% 4 3 3 3 4 4 41%	5352
	11th to 20th	Night	12% 9% 3 5% 3 3 3 3 5% 5% 48%	5090
	21st to end	Night	14% 9% 3 7% 5% 5% 4 4 5% 7% 37%	5355
April	1st to 10th	Night	11% 6% 3 5% 4 4 4 3 6% 8% 48%	2100
	11th to 20th	Night	14% 8% 2 6% 4 3 3 4 6% 6% 44%	2075
	21st to end	Night	18% 9% 3 6% 4 4 3 2 4 6% 41%	2100
May	1st to 10th	Night	16% 9% 2 6% 5% 4 4 3 6% 7% 37%	5832
	11th to 20th	Night	14% 7% 2 6% 3 4 4 3 6% 9% 43%	4798
	21st to end	Night	21% 10% 3 7% 5% 4 4 4 5% 7% 30%	5139
June	1st to 10th	Night	9% 4 2 5% 3 4 6% 4 6% 10% 47%	1680
	11th to 20th	Night	7% 4 1 4 3 3 4 4 6% 10% 54%	1680
	21st to end	Night	4 3 1 3 4 4 5% 4 6% 9% 57%	1680
July	1st to 10th	Night	10% 5% 2 6% 3 4 4 4 6% 9% 48%	4708
	11th to 20th	Night	5% 5% 2 6% 4 4 5% 4 6% 10% 51%	4820
	21st to end	Night	6% 5% 2 6% 4 4 5% 4 6% 10% 47%	5770
August	1st to 10th	Night	9% 4 2 4 4 4 4 4 5% 8% 54%	4171
	11th to 20th	Night	7% 4 2 6% 3 4 3 4 5% 8% 53%	4560
	21st to end	Night	5% 4 1 4 3 3 3 3 5% 8% 60%	5046
September	1st to 10th	Night	11% 6% 2 5% 3 4 3 3 5% 6% 53%	2100
	11th to 20th	Night	8% 6% 2 4 3 4 4 3 6% 8% 52%	2100
	21st to end	Night	10% 5% 2 5% 4 3 4 3 5% 7% 52%	2332
October	1st to 10th	Night	7% 3 1 5% 3 3 3 2 4 6% 64%	2520
	11th to 20th	Night	13% 5% 1 5% 3 3 3 2 4 6% 55%	2437
	21st to end	Night	20% 7% 2 5% 2 3 3 2 4 5% 48%	2640
November	1st to 10th	Night	11% 6% 2 5% 4 3 3 2 4 6% 56%	2620
	11th to 20th	Night	13% 7% 2 4 3 4 4 3 4 6% 49%	2730
	21st to end	Night	16% 11% 3 6% 4 3 3 2 3 5% 44%	2793
December	1st to 10th	Night	12% 10% 3 7% 4 3 3 3 4 6% 46%	4720
	11th to 20th	Night	13% 10% 4 6% 4 4 4 3 4 5% 43%	5339
	21st to end	Night	20% 19% 5% 8% 4 4 3 3 4 4 26%	7150

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	46% 4 11% 24% 12% 3	4734
	11th to 20th	Day	36% 4 6% 28% 19% 6%	5310
	21st to end	Day	45% 4 9% 18% 15% 9%	5812
February	1st to 10th	Day	49% 5% 12% 21% 13% 1	1890
	11th to 20th	Day	46% 6% 11% 18% 14% 5%	2028
	21st to end	Day	44% 5% 8% 23% 14% 6%	1730
March	1st to 10th	Day	43% 4 6% 19% 17% 10%	4764
	11th to 20th	Day	31% 5% 8% 25% 22% 8%	5090
	21st to end	Day	41% 7% 14% 27% 10% 1	5816
April	1st to 10th	Day	38% 6% 13% 23% 19% 2	2520
	11th to 20th	Day	45% 6% 10% 19% 16% 4	2494
	21st to end	Day	47% 5% 12% 22% 13% 1	2520
May	1st to 10th	Day	44% 9% 11% 23% 13% 1	7056
	11th to 20th	Day	46% 6% 11% 20% 16% 1	8077
	21st to end	Day	51% 7% 9% 19% 13% 2	9061
June	1st to 10th	Day	36% 9% 13% 25% 16% 1	2940
	11th to 20th	Day	31% 8% 12% 27% 19% 3	2940
	21st to end	Day	29% 9% 19% 23% 15% 4	2940
July	1st to 10th	Day	36% 7% 13% 27% 16% 2	8211
	11th to 20th	Day	33% 10% 17% 27% 13% 1	8087
	21st to end	Day	34% 7% 20% 30% 9% 1	8155
August	1st to 10th	Day	28% 7% 15% 29% 21%	5982
	11th to 20th	Day	33% 6% 15% 29% 15% 2	5522
	21st to end	Day	26% 5% 13% 38% 15% 3	6079
September	1st to 10th	Day	31% 7% 12% 27% 19% 4	2520
	11th to 20th	Day	33% 6% 10% 26% 23% 2	2517
	21st to end	Day	34% 7% 8% 25% 24% 3	2264
October	1st to 10th	Day	18% 3 6% 19% 44% 11%	3360
	11th to 20th	Day	23% 3 6% 21% 36% 11%	3270
	21st to end	Day	31% 3 7% 30% 24% 4	3538
November	1st to 10th	Day	34% 4 10% 25% 21% 6%	1897
	11th to 20th	Day	38% 4 9% 22% 20% 7%	1890
	21st to end	Day	45% 4 9% 23% 17% 2	1822
December	1st to 10th	Day	37% 3 8% 36% 15% 1	2690
	11th to 20th	Day	45% 4 8% 22% 19% 1	3085
	21st to end	Day	60% 6% 10% 13% 9% 1	4070
January	1st to 10th	Night	49% 6% 11% 21% 12% 1	8173
	11th to 20th	Night	41% 5% 6% 23% 22% 4	7680
	21st to end	Night	48% 4 8% 19% 16% 3	8402
February	1st to 10th	Night	48% 5% 10% 21% 14% 2	2730
	11th to 20th	Night	44% 5% 11% 21% 16% 3	2487
	21st to end	Night	45% 5% 8% 22% 16% 5%	2076
March	1st to 10th	Night	47% 5% 6% 20% 16% 5%	5352
	11th to 20th	Night	38% 5% 9% 22% 18% 8%	5090
	21st to end	Night	43% 9% 14% 24% 11% 1	5355
April	1st to 10th	Night	34% 5% 14% 26% 19% 3	2100
	11th to 20th	Night	39% 6% 11% 22% 17% 4	2075
	21st to end	Night	45% 5% 10% 23% 16% 1	2100
May	1st to 10th	Night	44% 8% 15% 21% 11% 1	5862
	11th to 20th	Night	38% 7% 13% 25% 15% 2	4799
	21st to end	Night	52% 8% 10% 18% 10% 2	5149
June	1st to 10th	Night	31% 8% 16% 24% 18% 2	1680
	11th to 20th	Night	24% 7% 13% 31% 21% 4	1680
	21st to end	Night	21% 9% 17% 29% 18% 6%	1680
July	1st to 10th	Night	32% 7% 16% 25% 18% 2	4670
	11th to 20th	Night	28% 9% 17% 29% 16% 1	4775
	21st to end	Night	32% 7% 20% 31% 10% 1	5641
August	1st to 10th	Night	28% 7% 16% 28% 21% 1	4161
	11th to 20th	Night	28% 6% 19% 29% 16% 2	4590
	21st to end	Night	23% 4 14% 37% 19% 2	5046
September	1st to 10th	Night	32% 5% 10% 27% 21% 5%	2100
	11th to 20th	Night	29% 7% 12% 27% 24% 2	2100
	21st to end	Night	31% 7% 9% 23% 26% 3	2332
October	1st to 10th	Night	14% 3 7% 16% 48% 13%	4040
	11th to 20th	Night	22% 3 7% 21% 31% 15%	3936
	21st to end	Night	31% 4 8% 26% 26% 6%	4252
November	1st to 10th	Night	31% 4 12% 27% 22% 5%	2620
	11th to 20th	Night	36% 4 8% 24% 22% 6%	2730
	21st to end	Night	44% 4 7% 24% 19% 2	2793
December	1st to 10th	Night	40% 5% 9% 29% 17% 1	4720
	11th to 20th	Night	43% 5% 11% 21% 19% 2	5341
	21st to end	Night	59% 7% 11% 15% 7% 1	7150

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	28% 24% 36% 10% 2	330
	11th to 20th	Day	32% 27% 35% 7%	330
	21st to end	Day	24% 31% 35% 9% 1	363
February	1st to 10th	Day	27% 28% 31% 12% 2	330
	11th to 20th	Day	35% 28% 29% 6% 1 1	330
	21st to end	Day	32% 26% 33% 8% 1	273
March	1st to 10th	Day	25% 25% 38% 9% 2	330
	11th to 20th	Day	32% 25% 34% 8% 2	330
	21st to end	Day	31% 25% 34% 8% 2	465
April	1st to 10th	Day	23% 21% 37% 14% 4	540
	11th to 20th	Day	28% 23% 30% 14% 4 1	532
	21st to end	Day	24% 21% 34% 16% 4 1	540
May	1st to 10th	Day	22% 18% 39% 15% 5% 1	543
	11th to 20th	Day	20% 15% 33% 21% 9% 2	740
	21st to end	Day	17% 12% 34% 24% 10% 3	844
June	1st to 10th	Day	13% 7% 29% 27% 20% 3	780
	11th to 20th	Day	9% 6% 28% 36% 17% 3	780
	21st to end	Day	6% 7% 33% 34% 16% 3	780
July	1st to 10th	Day	12% 3 20% 31% 26% 8%	771
	11th to 20th	Day	5% 5% 21% 40% 23% 5%	768
	21st to end	Day	9% 5% 20% 36% 25% 5%	849
August	1st to 10th	Day	10% 3 19% 41% 21% 6%	771
	11th to 20th	Day	13% 3 22% 31% 25% 6%	559
	21st to end	Day	10% 2 18% 33% 29% 9%	627
September	1st to 10th	Day	11% 5% 19% 37% 23% 5%	570
	11th to 20th	Day	10% 3 20% 33% 25% 10%	570
	21st to end	Day	13% 10% 27% 27% 17% 5%	524
October	1st to 10th	Day	10% 9% 36% 33% 10% 2	360
	11th to 20th	Day	21% 15% 36% 22% 5% 1	339
	21st to end	Day	32% 21% 31% 13% 2	363
November	1st to 10th	Day	16% 18% 41% 19% 4 2	330
	11th to 20th	Day	24% 21% 34% 15% 6% 1	330
	21st to end	Day	32% 17% 32% 14% 4	330
December	1st to 10th	Day	22% 27% 33% 12% 4 2	330
	11th to 20th	Day	28% 24% 33% 12% 2 1	330
	21st to end	Day	30% 25% 34% 9% 2	363
January	1st to 10th	Night	22% 25% 34% 16% 3	1050
	11th to 20th	Night	25% 28% 32% 13% 3	1050
	21st to end	Night	20% 26% 38% 15% 1	1155
February	1st to 10th	Night	25% 21% 37% 15% 1	1050
	11th to 20th	Night	25% 22% 38% 14% 1	851
	21st to end	Night	25% 23% 35% 16% 1	692
March	1st to 10th	Night	26% 19% 37% 16% 2	777
	11th to 20th	Night	26% 18% 35% 18% 3	630
	21st to end	Night	25% 20% 33% 17% 4	693
April	1st to 10th	Night	16% 22% 37% 22% 3	630
	11th to 20th	Night	21% 18% 32% 24% 5%	623
	21st to end	Night	23% 15% 36% 21% 5%	630
May	1st to 10th	Night	18% 11% 36% 27% 8%	630
	11th to 20th	Night	20% 9% 33% 26% 12% 1	621
	21st to end	Night	13% 8% 28% 32% 16% 2	683
June	1st to 10th	Night	12% 5% 22% 36% 23% 2	630
	11th to 20th	Night	8% 3 25% 43% 19% 2	630
	21st to end	Night	4 3 30% 41% 21% 1	630
July	1st to 10th	Night	11% 2 13% 36% 32% 7%	615
	11th to 20th	Night	5% 3 15% 44% 28% 4	612
	21st to end	Night	8% 3 16% 44% 27% 2	690
August	1st to 10th	Night	7% 3 17% 38% 32% 3	627
	11th to 20th	Night	8% 2 16% 42% 29% 3	624
	21st to end	Night	8% 1 15% 37% 34% 5%	693
September	1st to 10th	Night	11% 3 16% 37% 30% 3	630
	11th to 20th	Night	9% 3 17% 38% 29% 5%	630
	21st to end	Night	11% 7% 26% 26% 26% 4	820
October	1st to 10th	Night	8% 6% 28% 35% 20% 3	840
	11th to 20th	Night	16% 12% 34% 26% 11% 1	813
	21st to end	Night	25% 15% 33% 20% 6%	880
November	1st to 10th	Night	13% 12% 42% 24% 7% 1	820
	11th to 20th	Night	20% 18% 32% 24% 6% 1	840
	21st to end	Night	25% 20% 33% 18% 4	903
December	1st to 10th	Night	24% 17% 37% 18% 3	1050
	11th to 20th	Night	24% 18% 36% 20% 3	1050
	21st to end	Night	26% 23% 33% 16% 2	1155

Page generated at 2026-10-11 04:06:31. Version ac07

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