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 2025-06-10.

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% 8% 3 6% 4 4 4 4 5% 7% 43%	119453
	Night	13% 9% 3 7% 4 4 4 3 5% 6% 44%	118981
Transparency	Day	39% 6% 11% 24% 17% 4	123091
	Night	39% 6% 11% 23% 18% 4	123487
Seeing	Day	18% 14% 29% 23% 13% 3	16323
	Night	18% 14% 30% 25% 11% 1	26210

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	14% 11% 4 12% 4 4 4 2 4 5% 37%	3645
	11th to 20th	Day	10% 9% 4 8% 4 4 3 3 4 5% 46%	4080
	21st to end	Day	17% 9% 4 8% 3 3 3 3 4 5% 40%	4488
February	1st to 10th	Day	15% 11% 4 8% 5% 4 4 3 5% 6% 35%	1800
	11th to 20th	Day	15% 10% 3 8% 4 4 4 4 6% 7% 37%	1919
	21st to end	Day	14% 11% 2 7% 3 4 5% 4 6% 6% 39%	1650
March	1st to 10th	Day	15% 12% 3 5% 3 3 3 2 4 4 46%	4660
	11th to 20th	Day	10% 7% 2 4 3 3 4 3 5% 7% 53%	4980
	21st to end	Day	13% 9% 3 6% 5% 5% 4 4 6% 7% 38%	5688
April	1st to 10th	Day	12% 6% 2 7% 4 4 4 3 5% 8% 45%	2400
	11th to 20th	Day	17% 8% 3 6% 4 4 4 3 5% 6% 40%	2374
	21st to end	Day	18% 8% 3 6% 5% 4 4 3 5% 6% 36%	2400
May	1st to 10th	Day	15% 8% 3 8% 5% 5% 6% 4 7% 9% 29%	5405
	11th to 20th	Day	16% 8% 3 7% 5% 4 5% 4 6% 8% 34%	6209
	21st to end	Day	17% 8% 2 6% 4 4 4 4 4 6% 40%	6935
June	1st to 10th	Day	10% 5% 2 6% 4 5% 5% 4 6% 9% 43%	2787
	11th to 20th	Day	6% 5% 1 5% 5% 4 5% 4 7% 9% 49%	2660
	21st to end	Day	6% 4 1 4 5% 6% 5% 5% 7% 10% 47%	2660
July	1st to 10th	Day	13% 4 2 6% 5% 4 6% 5% 7% 9% 40%	4440
	11th to 20th	Day	4 4 2 5% 4 5% 6% 5% 6% 10% 49%	4378
	21st to end	Day	8% 6% 2 7% 6% 6% 6% 5% 8% 10% 34%	4465
August	1st to 10th	Day	6% 3 2 5% 3 4 4 5% 7% 10% 51%	4086
	11th to 20th	Day	11% 6% 2 6% 4 5% 5% 4 5% 8% 44%	3729
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 6% 9% 51%	4180
September	1st to 10th	Day	12% 5% 2 4 3 4 4 4 6% 8% 49%	2280
	11th to 20th	Day	11% 5% 2 6% 4 4 4 3 6% 8% 47%	2277
	21st to end	Day	10% 5% 3 5% 4 3 4 3 5% 7% 51%	2048
October	1st to 10th	Day	9% 5% 2 5% 3 3 3 3 4 7% 56%	1900
	11th to 20th	Day	14% 6% 2 4 3 3 3 2 3 5% 54%	1900
	21st to end	Day	17% 8% 2 6% 3 3 3 2 4 5% 47%	2090
November	1st to 10th	Day	12% 6% 3 5% 3 3 4 3 4 5% 54%	1805
	11th to 20th	Day	12% 9% 3 6% 3 3 4 3 4 6% 47%	1800
	21st to end	Day	15% 10% 3 6% 4 3 4 3 4 4 44%	1735
December	1st to 10th	Day	10% 10% 2 6% 3 3 3 2 4 6% 50%	2610
	11th to 20th	Day	13% 11% 5% 7% 4 3 3 3 4 5% 40%	3008
	21st to end	Day	18% 20% 6% 8% 4 3 3 3 4 4 27%	3982
January	1st to 10th	Night	14% 11% 6% 12% 5% 3 3 3 4 4 33%	6302
	11th to 20th	Night	11% 9% 4 12% 5% 4 5% 3 4 5% 40%	5900
	21st to end	Night	16% 12% 4 7% 4 4 3 2 4 4 40%	6490
February	1st to 10th	Night	17% 11% 4 9% 4 4 3 3 5% 5% 35%	2600
	11th to 20th	Night	14% 10% 3 8% 4 3 3 2 4 6% 42%	2365
	21st to end	Night	16% 7% 4 8% 5% 3 4 3 3 5% 41%	1980
March	1st to 10th	Night	15% 14% 3 6% 4 3 3 3 4 4 41%	5235
	11th to 20th	Night	12% 9% 3 5% 3 3 3 3 5% 5% 48%	4980
	21st to end	Night	14% 10% 3 7% 5% 5% 4 4 5% 7% 36%	5239
April	1st to 10th	Night	11% 6% 3 5% 3 4 4 3 5% 8% 48%	2000
	11th to 20th	Night	14% 8% 2 6% 4 3 3 3 5% 6% 45%	1975
	21st to end	Night	18% 8% 3 6% 5% 4 3 2 4 6% 41%	2000
May	1st to 10th	Night	18% 9% 2 6% 5% 4 4 3 6% 7% 35%	4490
	11th to 20th	Night	14% 8% 2 6% 3 4 4 3 6% 8% 41%	3699
	21st to end	Night	19% 8% 2 6% 4 4 4 3 5% 7% 37%	3942
June	1st to 10th	Night	9% 4 2 6% 3 4 6% 4 6% 10% 47%	1597
	11th to 20th	Night	6% 4 1 3 3 3 4 4 6% 10% 56%	1520
	21st to end	Night	3 3 1 3 4 4 5% 4 6% 9% 58%	1520
July	1st to 10th	Night	13% 4 1 5% 3 4 4 3 5% 9% 48%	2530
	11th to 20th	Night	5% 3 1 4 3 3 4 3 5% 9% 61%	2587
	21st to end	Night	7% 7% 3 8% 5% 5% 5% 5% 6% 8% 41%	3098
August	1st to 10th	Night	5% 3 1 3 3 3 3 4 6% 9% 58%	2851
	11th to 20th	Night	9% 5% 2 7% 4 4 4 4 6% 9% 47%	3100
	21st to end	Night	5% 4 1 4 3 3 4 3 6% 8% 58%	3476
September	1st to 10th	Night	11% 6% 2 5% 3 4 3 3 5% 6% 53%	1900
	11th to 20th	Night	8% 6% 2 4 4 4 4 3 6% 7% 52%	1900
	21st to end	Night	9% 5% 2 5% 3 3 4 4 5% 7% 53%	2110
October	1st to 10th	Night	7% 3 1 5% 3 3 3 3 4 6% 64%	2280
	11th to 20th	Night	13% 5% 1 5% 3 3 3 2 4 5% 54%	2280
	21st to end	Night	19% 7% 2 5% 2 3 3 2 4 5% 49%	2508
November	1st to 10th	Night	11% 5% 2 5% 3 3 3 2 4 6% 56%	2492
	11th to 20th	Night	14% 7% 2 4 3 4 4 3 4 6% 49%	2600
	21st to end	Night	16% 11% 3 6% 4 3 3 2 3 5% 45%	2660
December	1st to 10th	Night	12% 10% 3 7% 4 3 3 3 4 6% 46%	4580
	11th to 20th	Night	13% 11% 4 6% 4 4 4 3 4 5% 43%	5199
	21st to end	Night	20% 19% 5% 8% 4 4 3 3 4 4 25%	6996

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	49% 5% 10% 20% 13% 3	3646
	11th to 20th	Day	39% 5% 7% 27% 17% 6%	4080
	21st to end	Day	46% 4 10% 14% 16% 10%	4488
February	1st to 10th	Day	49% 5% 11% 21% 12% 1	1800
	11th to 20th	Day	46% 6% 12% 17% 14% 5%	1929
	21st to end	Day	44% 5% 9% 23% 14% 6%	1650
March	1st to 10th	Day	43% 4 6% 19% 17% 10%	4660
	11th to 20th	Day	30% 5% 8% 25% 23% 8%	4980
	21st to end	Day	42% 8% 14% 26% 10% 1	5690
April	1st to 10th	Day	37% 5% 13% 23% 20% 2	2400
	11th to 20th	Day	44% 6% 10% 19% 16% 4	2374
	21st to end	Day	48% 6% 11% 21% 13% 1	2400
May	1st to 10th	Day	47% 10% 12% 19% 11% 1	5440
	11th to 20th	Day	46% 8% 11% 21% 13% 1	6213
	21st to end	Day	43% 7% 9% 22% 16% 2	6949
June	1st to 10th	Day	36% 9% 13% 26% 15% 2	2787
	11th to 20th	Day	29% 8% 13% 27% 20% 3	2660
	21st to end	Day	28% 10% 19% 23% 15% 5%	2660
July	1st to 10th	Day	38% 7% 13% 28% 12% 2	4371
	11th to 20th	Day	28% 8% 13% 33% 16% 2	4303
	21st to end	Day	41% 9% 16% 26% 8% 1	4325
August	1st to 10th	Day	25% 7% 17% 31% 19%	4072
	11th to 20th	Day	39% 7% 13% 23% 16% 2	3765
	21st to end	Day	29% 6% 15% 35% 13% 3	4179
September	1st to 10th	Day	32% 7% 12% 26% 18% 5%	2280
	11th to 20th	Day	35% 6% 10% 25% 23% 2	2277
	21st to end	Day	32% 7% 8% 27% 24% 3	2048
October	1st to 10th	Day	17% 3 6% 19% 44% 11%	3160
	11th to 20th	Day	23% 3 6% 21% 37% 11%	3140
	21st to end	Day	30% 3 7% 30% 25% 4	3428
November	1st to 10th	Day	34% 4 10% 24% 22% 6%	1805
	11th to 20th	Day	38% 4 8% 22% 20% 8%	1800
	21st to end	Day	45% 3 9% 24% 18% 1	1735
December	1st to 10th	Day	37% 3 8% 36% 15% 1	2610
	11th to 20th	Day	46% 4 8% 22% 19% 2	3005
	21st to end	Day	60% 6% 10% 13% 10% 1	3982
January	1st to 10th	Night	53% 6% 9% 18% 14% 1	6302
	11th to 20th	Night	45% 6% 7% 22% 18% 3	5900
	21st to end	Night	47% 5% 7% 19% 18% 4	6490
February	1st to 10th	Night	50% 5% 9% 20% 13% 2	2600
	11th to 20th	Night	45% 4 12% 20% 17% 3	2366
	21st to end	Night	45% 5% 8% 22% 16% 4	1980
March	1st to 10th	Night	47% 5% 6% 20% 17% 5%	5235
	11th to 20th	Night	37% 5% 9% 22% 19% 8%	4980
	21st to end	Night	43% 9% 14% 23% 11% 1	5239
April	1st to 10th	Night	34% 5% 13% 26% 19% 3	2000
	11th to 20th	Night	39% 6% 11% 23% 17% 4	1975
	21st to end	Night	45% 5% 10% 23% 16% 1	2000
May	1st to 10th	Night	46% 9% 15% 17% 12% 1	4520
	11th to 20th	Night	41% 7% 13% 23% 13% 3	3700
	21st to end	Night	45% 9% 10% 21% 12% 3	3950
June	1st to 10th	Night	32% 8% 16% 24% 18% 2	1597
	11th to 20th	Night	22% 7% 13% 32% 21% 4	1520
	21st to end	Night	20% 9% 17% 29% 19% 7%	1520
July	1st to 10th	Night	33% 6% 15% 27% 15% 3	2490
	11th to 20th	Night	21% 6% 13% 38% 19% 2	2539
	21st to end	Night	38% 9% 16% 24% 12% 2	2999
August	1st to 10th	Night	20% 8% 20% 30% 21% 1	2841
	11th to 20th	Night	33% 6% 18% 23% 17% 3	3130
	21st to end	Night	24% 5% 16% 36% 16% 3	3476
September	1st to 10th	Night	33% 5% 9% 27% 20% 6%	1900
	11th to 20th	Night	30% 7% 11% 25% 26% 2	1900
	21st to end	Night	29% 8% 9% 24% 26% 4	2110
October	1st to 10th	Night	14% 3 7% 16% 48% 13%	3800
	11th to 20th	Night	22% 3 7% 20% 32% 16%	3779
	21st to end	Night	30% 4 8% 26% 26% 7%	4120
November	1st to 10th	Night	31% 4 11% 26% 22% 5%	2492
	11th to 20th	Night	36% 4 8% 22% 23% 6%	2600
	21st to end	Night	43% 4 8% 24% 20% 2	2660
December	1st to 10th	Night	39% 5% 9% 29% 17% 1	4580
	11th to 20th	Night	43% 5% 11% 21% 19% 2	5201
	21st to end	Night	60% 7% 11% 15% 6% 1	6996

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% 25% 35% 11% 1	300
	11th to 20th	Day	32% 25% 35% 7%	300
	21st to end	Day	24% 31% 35% 9% 1	330
February	1st to 10th	Day	28% 28% 31% 12% 1	300
	11th to 20th	Day	35% 27% 29% 7% 1 1	300
	21st to end	Day	31% 26% 33% 8% 1	249
March	1st to 10th	Day	26% 24% 39% 10% 2	300
	11th to 20th	Day	32% 25% 32% 9% 2	300
	21st to end	Day	33% 24% 33% 9% 2	427
April	1st to 10th	Day	23% 22% 36% 15% 4	500
	11th to 20th	Day	28% 23% 30% 14% 4 1	492
	21st to end	Day	25% 21% 33% 15% 5% 1	500
May	1st to 10th	Day	23% 17% 38% 16% 5% 1	503
	11th to 20th	Day	20% 14% 33% 22% 10% 2	692
	21st to end	Day	15% 12% 34% 25% 10% 4	789
June	1st to 10th	Day	13% 7% 27% 28% 21% 4	726
	11th to 20th	Day	8% 4 28% 38% 18% 4	680
	21st to end	Day	6% 7% 34% 32% 17% 4	680
July	1st to 10th	Day	12% 3 19% 30% 27% 8%	671
	11th to 20th	Day	4 4 22% 40% 24% 5%	668
	21st to end	Day	9% 5% 20% 36% 25% 5%	739
August	1st to 10th	Day	10% 3 18% 41% 23% 6%	671
	11th to 20th	Day	14% 3 23% 29% 24% 6%	479
	21st to end	Day	11% 2 17% 31% 29% 10%	539
September	1st to 10th	Day	12% 5% 20% 35% 23% 6%	490
	11th to 20th	Day	11% 3 22% 31% 23% 10%	490
	21st to end	Day	13% 10% 27% 27% 17% 5%	448
October	1st to 10th	Day	11% 11% 34% 31% 11% 3	300
	11th to 20th	Day	22% 16% 38% 19% 5% 1	300
	21st to end	Day	30% 22% 30% 15% 2	330
November	1st to 10th	Day	16% 17% 41% 20% 4 2	300
	11th to 20th	Day	25% 20% 33% 15% 6% 1	300
	21st to end	Day	30% 18% 33% 15% 4	300
December	1st to 10th	Day	21% 27% 32% 13% 4 2	300
	11th to 20th	Day	29% 24% 31% 13% 3 1	300
	21st to end	Day	32% 25% 32% 9% 2	330
January	1st to 10th	Night	22% 26% 34% 16% 3	1000
	11th to 20th	Night	25% 27% 32% 13% 3	1000
	21st to end	Night	20% 25% 38% 15% 1	1100
February	1st to 10th	Night	27% 21% 36% 15% 1	1000
	11th to 20th	Night	24% 22% 39% 14% 1	810
	21st to end	Night	25% 23% 35% 16% 1	660
March	1st to 10th	Night	26% 19% 37% 17% 2	740
	11th to 20th	Night	25% 18% 35% 19% 3	600
	21st to end	Night	26% 19% 33% 18% 4	660
April	1st to 10th	Night	16% 21% 37% 22% 3	600
	11th to 20th	Night	21% 17% 31% 25% 6%	593
	21st to end	Night	23% 15% 35% 21% 6%	600
May	1st to 10th	Night	18% 11% 36% 27% 8%	600
	11th to 20th	Night	19% 8% 33% 26% 12% 1	591
	21st to end	Night	13% 9% 29% 31% 16% 2	650
June	1st to 10th	Night	12% 5% 21% 36% 24% 2	599
	11th to 20th	Night	7% 2 25% 44% 21% 2	570
	21st to end	Night	3 3 30% 40% 22% 2	570
July	1st to 10th	Night	11% 1 14% 35% 32% 7%	555
	11th to 20th	Night	6% 3 15% 44% 28% 4	552
	21st to end	Night	8% 3 16% 43% 28% 3	624
August	1st to 10th	Night	6% 3 15% 39% 33% 3	567
	11th to 20th	Night	8% 2 16% 40% 30% 3	564
	21st to end	Night	8% 1 16% 34% 36% 5%	627
September	1st to 10th	Night	12% 3 17% 35% 29% 4	570
	11th to 20th	Night	10% 3 17% 37% 29% 5%	570
	21st to end	Night	11% 7% 27% 26% 25% 4	742
October	1st to 10th	Night	8% 6% 29% 33% 20% 4	760
	11th to 20th	Night	17% 13% 35% 25% 10% 1	760
	21st to end	Night	24% 16% 33% 21% 6%	836
November	1st to 10th	Night	13% 12% 42% 24% 8% 1	780
	11th to 20th	Night	20% 17% 32% 24% 6% 1	800
	21st to end	Night	24% 20% 33% 18% 4	860
December	1st to 10th	Night	25% 17% 37% 18% 3	1000
	11th to 20th	Night	24% 17% 36% 20% 3	1000
	21st to end	Night	26% 23% 33% 16% 2	1100

Page generated at 2025-06-07 09:28:14. Version ac07

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