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 2024-03-23.

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	13% 7% 3 5% 5% 3 5% 5% 5% 7% 42%	78808
	Night	13% 8% 3 5% 5% 3 4 4 5% 6% 44%	81109
Transparency	Day	40% 7% 12% 23% 16% 3	78521
	Night	40% 6% 11% 23% 17% 3	80917
Seeing	Day	18% 13% 28% 24% 13% 3	14611
	Night	18% 14% 30% 25% 12% 1	24632

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% 5% 8% 5% 3 4 4 4 5% 39%	2541
	11th to 20th	Day	14% 9% 4 6% 5% 3 4 4 4 5% 43%	2850
	21st to end	Day	20% 10% 5% 6% 4 2 3 3 3 5% 37%	3135
February	1st to 10th	Day	15% 10% 4 8% 5% 3 4 4 5% 6% 36%	1710
	11th to 20th	Day	14% 9% 4 6% 4 3 4 5% 6% 8% 38%	1820
	21st to end	Day	14% 11% 3 6% 4 3 5% 5% 5% 6% 38%	1570
March	1st to 10th	Day	14% 9% 5% 6% 4 2 4 3 4 6% 44%	1972
	11th to 20th	Day	19% 10% 3 5% 5% 2 5% 4 5% 6% 36%	2090
	21st to end	Day	19% 12% 4 7% 6% 4 5% 4 4 6% 30%	2287
April	1st to 10th	Day	10% 6% 2 5% 5% 3 4 4 5% 8% 46%	2160
	11th to 20th	Day	18% 8% 3 5% 5% 3 4 4 5% 6% 39%	2134
	21st to end	Day	19% 8% 4 6% 5% 3 4 4 5% 6% 37%	2160
May	1st to 10th	Day	17% 7% 3 5% 5% 3 5% 4 6% 8% 36%	2160
	11th to 20th	Day	17% 6% 2 5% 5% 3 4 5% 5% 8% 41%	2425
	21st to end	Day	11% 7% 3 6% 6% 4 6% 7% 6% 8% 36%	2725
June	1st to 10th	Day	9% 5% 3 5% 5% 4 5% 5% 6% 9% 44%	2520
	11th to 20th	Day	6% 4 2 4 5% 3 5% 6% 7% 9% 48%	2520
	21st to end	Day	6% 3 2 4 5% 4 5% 6% 7% 10% 48%	2520
July	1st to 10th	Day	11% 4 2 5% 6% 3 6% 6% 7% 11% 40%	2520
	11th to 20th	Day	5% 4 1 4 4 4 7% 6% 6% 9% 49%	2486
	21st to end	Day	7% 5% 2 6% 6% 4 7% 6% 7% 9% 41%	2546
August	1st to 10th	Day	8% 4 2 5% 5% 4 6% 6% 8% 10% 40%	2324
	11th to 20th	Day	10% 6% 2 6% 6% 4 6% 6% 6% 9% 39%	2125
	21st to end	Day	9% 6% 2 5% 5% 3 5% 6% 6% 8% 45%	2376
September	1st to 10th	Day	13% 5% 2 4 3 3 4 4 6% 8% 48%	2160
	11th to 20th	Day	10% 4 2 5% 5% 3 4 4 6% 8% 48%	2158
	21st to end	Day	9% 5% 2 4 4 2 4 4 5% 7% 53%	1941
October	1st to 10th	Day	9% 5% 2 5% 4 2 4 4 4 7% 54%	1800
	11th to 20th	Day	15% 6% 2 3 4 3 3 3 3 6% 52%	1800
	21st to end	Day	18% 8% 3 5% 4 2 2 3 4 5% 46%	1980
November	1st to 10th	Day	11% 5% 3 4 4 3 4 3 4 5% 55%	1713
	11th to 20th	Day	13% 8% 3 6% 4 2 4 3 4 6% 47%	1710
	21st to end	Day	15% 10% 3 6% 4 2 4 4 4 5% 44%	1649
December	1st to 10th	Day	14% 10% 3 6% 5% 3 4 3 4 6% 41%	1520
	11th to 20th	Day	14% 10% 5% 7% 6% 3 4 3 4 5% 38%	1918
	21st to end	Day	14% 16% 6% 7% 5% 3 4 4 5% 5% 30%	2783
January	1st to 10th	Night	14% 10% 5% 8% 6% 3 4 4 4 5% 36%	4396
	11th to 20th	Night	13% 9% 4 10% 7% 3 6% 4 4 5% 34%	4120
	21st to end	Night	22% 13% 6% 6% 4 3 3 3 4 4 32%	4532
February	1st to 10th	Night	17% 10% 4 8% 5% 3 3 3 5% 5% 36%	2470
	11th to 20th	Night	13% 8% 4 7% 5% 2 4 3 4 6% 43%	2244
	21st to end	Night	16% 7% 4 7% 6% 3 4 3 3 5% 40%	1884
March	1st to 10th	Night	15% 11% 4 5% 5% 2 3 4 4 5% 43%	2223
	11th to 20th	Night	19% 9% 4 5% 4 3 4 4 4 5% 39%	2090
	21st to end	Night	19% 11% 4 6% 5% 3 4 5% 5% 5% 33%	2111
April	1st to 10th	Night	9% 5% 3 4 5% 2 4 4 5% 8% 50%	1800
	11th to 20th	Night	14% 8% 3 5% 5% 2 4 4 6% 6% 44%	1775
	21st to end	Night	19% 7% 3 5% 5% 2 4 3 4 6% 42%	1800
May	1st to 10th	Night	16% 6% 2 4 4 3 4 4 5% 7% 46%	1800
	11th to 20th	Night	16% 7% 2 4 3 3 5% 4 4 7% 45%	1465
	21st to end	Night	10% 7% 3 6% 6% 4 5% 5% 7% 9% 38%	1551
June	1st to 10th	Night	8% 4 2 4 4 3 6% 5% 6% 10% 48%	1440
	11th to 20th	Night	6% 4 2 3 3 2 4 5% 6% 10% 56%	1440
	21st to end	Night	3 2 1 3 4 3 5% 5% 6% 10% 58%	1440
July	1st to 10th	Night	9% 4 1 4 3 3 4 5% 5% 10% 52%	1440
	11th to 20th	Night	6% 2 2 3 4 2 4 4 6% 10% 58%	1469
	21st to end	Night	6% 4 2 5% 4 2 5% 6% 6% 9% 50%	1772
August	1st to 10th	Night	6% 4 2 3 5% 3 4 6% 7% 10% 50%	1613
	11th to 20th	Night	7% 3 2 4 4 3 4 5% 7% 9% 53%	1776
	21st to end	Night	7% 4 3 4 5% 3 4 4 5% 8% 54%	1980
September	1st to 10th	Night	12% 6% 2 4 4 3 3 4 5% 6% 52%	1800
	11th to 20th	Night	8% 5% 2 4 4 3 4 4 6% 7% 54%	1800
	21st to end	Night	9% 4 1 4 4 2 4 5% 5% 7% 55%	1998
October	1st to 10th	Night	7% 3 1 4 4 2 3 3 4 6% 62%	2160
	11th to 20th	Night	14% 5% 1 4 4 2 3 3 4 6% 52%	2160
	21st to end	Night	20% 7% 2 4 3 2 3 3 3 4 48%	2376
November	1st to 10th	Night	11% 5% 2 4 4 2 3 2 4 6% 57%	2364
	11th to 20th	Night	14% 6% 2 4 4 3 4 4 4 6% 49%	2470
	21st to end	Night	16% 10% 3 5% 4 2 3 3 3 5% 45%	2527
December	1st to 10th	Night	15% 11% 4 5% 5% 2 4 4 6% 7% 38%	2660
	11th to 20th	Night	15% 10% 5% 5% 5% 3 4 3 4 5% 41%	3279
	21st to end	Night	15% 19% 6% 8% 6% 3 4 4 5% 5% 26%	4884

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	45% 6% 10% 25% 12% 2	2542
	11th to 20th	Day	43% 5% 9% 24% 16% 2	2850
	21st to end	Day	50% 5% 10% 16% 15% 5%	3135
February	1st to 10th	Day	49% 5% 11% 21% 13% 1	1710
	11th to 20th	Day	44% 6% 12% 18% 14% 5%	1830
	21st to end	Day	45% 5% 9% 22% 12% 6%	1570
March	1st to 10th	Day	43% 6% 9% 21% 17% 5%	1972
	11th to 20th	Day	48% 6% 10% 18% 13% 4	2090
	21st to end	Day	55% 7% 10% 17% 9% 1	2287
April	1st to 10th	Day	36% 6% 13% 25% 19% 1	2160
	11th to 20th	Day	46% 6% 10% 19% 16% 3	2134
	21st to end	Day	48% 5% 11% 21% 13% 1	2160
May	1st to 10th	Day	46% 8% 12% 22% 11% 1	2160
	11th to 20th	Day	42% 7% 13% 22% 15% 2	2429
	21st to end	Day	44% 11% 14% 19% 12% 1	2725
June	1st to 10th	Day	35% 9% 14% 25% 16% 1	2520
	11th to 20th	Day	30% 8% 13% 26% 19% 3	2520
	21st to end	Day	28% 10% 18% 24% 15% 5%	2520
July	1st to 10th	Day	35% 9% 15% 24% 13% 4	2451
	11th to 20th	Day	28% 10% 15% 26% 18% 4	2411
	21st to end	Day	37% 9% 15% 27% 11% 1	2405
August	1st to 10th	Day	34% 11% 15% 26% 13%	2310
	11th to 20th	Day	39% 9% 14% 25% 12% 1	2125
	21st to end	Day	34% 7% 15% 23% 15% 6%	2376
September	1st to 10th	Day	33% 8% 13% 27% 16% 4	2160
	11th to 20th	Day	34% 6% 10% 25% 24% 2	2158
	21st to end	Day	30% 7% 7% 28% 25% 3	1941
October	1st to 10th	Day	30% 6% 10% 24% 25% 4	1800
	11th to 20th	Day	35% 4 8% 24% 23% 6%	1800
	21st to end	Day	42% 4 8% 25% 17% 5%	1980
November	1st to 10th	Day	33% 4 10% 24% 21% 6%	1713
	11th to 20th	Day	38% 4 8% 22% 20% 7%	1710
	21st to end	Day	45% 4 9% 23% 18% 2	1649
December	1st to 10th	Day	45% 4 10% 26% 13% 2	1520
	11th to 20th	Day	48% 5% 7% 18% 20% 1	1915
	21st to end	Day	54% 8% 9% 14% 12% 2	2783
January	1st to 10th	Night	46% 8% 10% 21% 13% 1	4396
	11th to 20th	Night	47% 8% 10% 22% 11% 2	4120
	21st to end	Night	54% 5% 9% 20% 11% 1	4532
February	1st to 10th	Night	49% 5% 9% 21% 14% 2	2470
	11th to 20th	Night	42% 5% 12% 21% 17% 3	2245
	21st to end	Night	47% 5% 8% 21% 15% 5%	1884
March	1st to 10th	Night	44% 6% 9% 20% 17% 5%	2223
	11th to 20th	Night	48% 5% 10% 21% 14% 3	2090
	21st to end	Night	52% 7% 12% 20% 9% 1	2111
April	1st to 10th	Night	33% 5% 13% 27% 19% 3	1800
	11th to 20th	Night	40% 6% 11% 22% 16% 4	1775
	21st to end	Night	45% 5% 9% 24% 16% 1	1800
May	1st to 10th	Night	38% 7% 14% 22% 17% 2	1800
	11th to 20th	Night	39% 8% 12% 21% 17% 2	1466
	21st to end	Night	41% 10% 13% 19% 14% 3	1552
June	1st to 10th	Night	30% 8% 17% 25% 18% 2	1440
	11th to 20th	Night	22% 7% 14% 32% 21% 4	1440
	21st to end	Night	19% 10% 16% 29% 19% 6%	1440
July	1st to 10th	Night	28% 8% 18% 25% 16% 4	1400
	11th to 20th	Night	23% 7% 17% 28% 20% 4	1421
	21st to end	Night	28% 10% 14% 31% 16% 1	1673
August	1st to 10th	Night	26% 11% 19% 29% 14% 2	1603
	11th to 20th	Night	25% 8% 18% 26% 20% 2	1776
	21st to end	Night	28% 7% 16% 25% 19% 5%	1980
September	1st to 10th	Night	33% 5% 10% 28% 19% 6%	1800
	11th to 20th	Night	29% 7% 12% 26% 26% 2	1800
	21st to end	Night	27% 8% 9% 25% 28% 4	1998
October	1st to 10th	Night	24% 5% 12% 27% 28% 4	2160
	11th to 20th	Night	34% 4 9% 25% 22% 6%	2160
	21st to end	Night	40% 4 9% 22% 20% 5%	2376
November	1st to 10th	Night	30% 4 12% 27% 22% 6%	2364
	11th to 20th	Night	36% 4 8% 22% 23% 6%	2470
	21st to end	Night	43% 4 8% 23% 20% 2	2527
December	1st to 10th	Night	44% 6% 11% 22% 16% 2	2660
	11th to 20th	Night	45% 5% 9% 23% 17% 2	3281
	21st to end	Night	56% 9% 10% 14% 9% 2	4884

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	29% 23% 35% 12% 1	270
	11th to 20th	Day	34% 23% 35% 8%	270
	21st to end	Day	25% 31% 34% 10% 1	297
February	1st to 10th	Day	29% 26% 32% 13% 1	270
	11th to 20th	Day	33% 26% 31% 8% 1 1	270
	21st to end	Day	32% 27% 31% 8% 1	225
March	1st to 10th	Day	24% 24% 40% 10% 1	270
	11th to 20th	Day	32% 23% 33% 10% 1	270
	21st to end	Day	33% 23% 33% 10% 2	357
April	1st to 10th	Day	20% 21% 38% 16% 5%	420
	11th to 20th	Day	27% 21% 31% 15% 5% 1	412
	21st to end	Day	25% 21% 33% 15% 4 1	420
May	1st to 10th	Day	23% 18% 37% 16% 6% 1	423
	11th to 20th	Day	20% 14% 31% 23% 10% 2	594
	21st to end	Day	14% 11% 34% 26% 12% 4	679
June	1st to 10th	Day	12% 6% 26% 29% 23% 4	630
	11th to 20th	Day	8% 4 28% 38% 18% 4	630
	21st to end	Day	6% 8% 33% 33% 17% 4	630
July	1st to 10th	Day	12% 2 18% 31% 29% 9%	621
	11th to 20th	Day	5% 4 22% 39% 25% 5%	618
	21st to end	Day	8% 4 19% 36% 26% 6%	684
August	1st to 10th	Day	10% 2 16% 42% 23% 6%	622
	11th to 20th	Day	15% 3 20% 30% 26% 7%	439
	21st to end	Day	11% 2 17% 31% 29% 10%	495
September	1st to 10th	Day	12% 5% 18% 35% 24% 6%	450
	11th to 20th	Day	9% 3 23% 31% 24% 11%	450
	21st to end	Day	11% 10% 26% 29% 18% 6%	411
October	1st to 10th	Day	13% 11% 36% 30% 9% 2	270
	11th to 20th	Day	23% 17% 40% 17% 3	270
	21st to end	Day	33% 22% 28% 15% 2	297
November	1st to 10th	Day	14% 17% 41% 20% 5% 2	270
	11th to 20th	Day	24% 20% 32% 17% 6%	270
	21st to end	Day	29% 17% 34% 16% 4	270
December	1st to 10th	Day	20% 27% 31% 14% 4 2	270
	11th to 20th	Day	28% 23% 32% 14% 3 1	270
	21st to end	Day	29% 26% 32% 10% 2	297
January	1st to 10th	Night	21% 26% 34% 16% 3	950
	11th to 20th	Night	25% 27% 32% 13% 3	950
	21st to end	Night	20% 25% 38% 16% 1	1045
February	1st to 10th	Night	26% 21% 36% 15% 1	950
	11th to 20th	Night	22% 22% 40% 14% 1	769
	21st to end	Night	26% 24% 34% 15% 1	628
March	1st to 10th	Night	25% 18% 38% 17% 2	703
	11th to 20th	Night	25% 17% 36% 19% 3	570
	21st to end	Night	26% 18% 34% 19% 4	600
April	1st to 10th	Night	14% 21% 38% 23% 4	540
	11th to 20th	Night	20% 17% 31% 26% 6%	533
	21st to end	Night	23% 15% 37% 21% 6%	540
May	1st to 10th	Night	18% 11% 36% 27% 8%	540
	11th to 20th	Night	20% 8% 33% 26% 12% 1	531
	21st to end	Night	13% 8% 28% 33% 17% 3	584
June	1st to 10th	Night	11% 4 20% 37% 26% 2	540
	11th to 20th	Night	8% 2 24% 44% 20% 2	540
	21st to end	Night	3 3 30% 41% 23% 2	540
July	1st to 10th	Night	10% 1 13% 35% 33% 8%	525
	11th to 20th	Night	6% 3 15% 44% 29% 4	522
	21st to end	Night	8% 3 15% 44% 28% 3	591
August	1st to 10th	Night	6% 3 15% 39% 34% 3	537
	11th to 20th	Night	8% 2 15% 40% 31% 3	534
	21st to end	Night	8% 1 16% 33% 37% 5%	594
September	1st to 10th	Night	13% 2 16% 36% 29% 4	540
	11th to 20th	Night	9% 2 17% 37% 29% 5%	540
	21st to end	Night	10% 7% 27% 26% 26% 4	702
October	1st to 10th	Night	8% 6% 30% 32% 20% 3	720
	11th to 20th	Night	18% 13% 35% 25% 9% 1	720
	21st to end	Night	25% 15% 33% 21% 6%	792
November	1st to 10th	Night	13% 12% 42% 25% 8% 1	740
	11th to 20th	Night	20% 17% 32% 24% 6% 1	760
	21st to end	Night	24% 20% 33% 18% 4	817
December	1st to 10th	Night	24% 16% 37% 19% 4	950
	11th to 20th	Night	24% 17% 36% 20% 3	950
	21st to end	Night	25% 23% 33% 17% 2	1045

Page generated at 2024-03-19 22:31:07. Version ac07

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