Cincinnati
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cincinnati clear sky chart from 2005-11-06 to 2026-03-03.

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	14% 9% 3 8% 5% 5% 5% 4 6% 7% 35%	131171
	Night	14% 10% 3 8% 5% 4 4 3 5% 7% 36%	130015
Transparency	Day	30% 38% 7% 15% 9% 1	134822
	Night	31% 37% 7% 15% 10% 1	134434
Seeing	Day	19% 11% 27% 23% 14% 6%	17054
	Night	20% 9% 25% 29% 15% 2	26843

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	16% 15% 6% 11% 5% 4 4 3 5% 6% 25%	4691
	11th to 20th	Day	11% 12% 6% 16% 7% 6% 4 3 4 4 29%	5106
	21st to end	Day	19% 11% 6% 10% 7% 6% 6% 3 5% 5% 22%	5780
February	1st to 10th	Day	18% 13% 5% 9% 4 4 4 3 5% 6% 30%	2014
	11th to 20th	Day	16% 11% 4 11% 5% 4 4 3 5% 6% 31%	2048
	21st to end	Day	18% 11% 5% 10% 5% 3 4 3 4 6% 31%	1730
March	1st to 10th	Day	17% 13% 5% 9% 5% 4 4 3 4 5% 31%	4518
	11th to 20th	Day	12% 8% 3 7% 4 4 4 4 5% 8% 39%	4980
	21st to end	Day	17% 10% 3 7% 5% 4 5% 3 6% 7% 34%	5465
April	1st to 10th	Day	17% 9% 3 7% 5% 4 5% 4 6% 7% 34%	2370
	11th to 20th	Day	16% 7% 4 7% 5% 4 5% 3 5% 6% 38%	2419
	21st to end	Day	18% 8% 3 6% 5% 5% 5% 3 5% 7% 35%	2600
May	1st to 10th	Day	19% 9% 3 7% 6% 6% 5% 4 6% 8% 28%	5862
	11th to 20th	Day	19% 9% 3 7% 5% 4 4 3 6% 7% 34%	5861
	21st to end	Day	12% 6% 3 8% 6% 6% 6% 5% 8% 10% 31%	6433
June	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 5% 6% 8% 40%	2608
	11th to 20th	Day	9% 5% 2 7% 4 5% 5% 4 6% 9% 43%	2800
	21st to end	Day	8% 5% 2 7% 6% 6% 5% 5% 5% 10% 40%	2800
July	1st to 10th	Day	9% 6% 2 7% 4 5% 5% 4 6% 10% 41%	6360
	11th to 20th	Day	8% 6% 2 8% 4 5% 6% 4 8% 11% 37%	6158
	21st to end	Day	10% 7% 3 8% 7% 6% 7% 6% 8% 9% 30%	6424
August	1st to 10th	Day	8% 5% 2 6% 5% 4 5% 4 8% 10% 44%	4234
	11th to 20th	Day	7% 5% 2 6% 5% 5% 5% 4 8% 11% 41%	4174
	21st to end	Day	6% 4 1 5% 4 4 3 3 5% 9% 55%	4317
September	1st to 10th	Day	12% 5% 2 6% 4 4 3 4 5% 7% 48%	2284
	11th to 20th	Day	7% 5% 2 6% 4 4 4 4 6% 8% 49%	2200
	21st to end	Day	16% 6% 2 5% 4 3 3 3 4 6% 47%	2200
October	1st to 10th	Day	10% 5% 2 6% 5% 4 4 3 5% 6% 50%	2200
	11th to 20th	Day	11% 7% 2 6% 5% 4 3 3 6% 6% 46%	2040
	21st to end	Day	19% 9% 2 7% 3 3 3 3 5% 6% 39%	2040
November	1st to 10th	Day	9% 8% 2 6% 5% 4 4 3 4 6% 51%	1852
	11th to 20th	Day	14% 11% 4 9% 5% 4 4 4 5% 7% 36%	1890
	21st to end	Day	17% 11% 4 8% 5% 4 4 3 4 6% 35%	1890
December	1st to 10th	Day	17% 10% 3 8% 5% 3 4 3 3 5% 38%	3020
	11th to 20th	Day	18% 13% 5% 10% 5% 5% 5% 3 5% 5% 26%	3463
	21st to end	Day	21% 18% 5% 10% 6% 4 4 3 4 5% 18%	4340
January	1st to 10th	Night	13% 15% 6% 13% 6% 5% 5% 4 5% 6% 22%	8232
	11th to 20th	Night	12% 15% 6% 15% 6% 5% 5% 3 4 4 24%	7828
	21st to end	Night	17% 12% 4 9% 6% 5% 4 3 4 5% 32%	8401
February	1st to 10th	Night	19% 12% 4 10% 5% 4 5% 3 4 6% 28%	2604
	11th to 20th	Night	17% 10% 4 9% 6% 4 4 3 5% 5% 31%	2458
	21st to end	Night	20% 13% 4 8% 4 3 4 3 5% 6% 31%	2076
March	1st to 10th	Night	18% 13% 3 6% 4 3 4 3 4 5% 37%	5365
	11th to 20th	Night	12% 7% 2 6% 4 4 5% 4 6% 7% 43%	4980
	21st to end	Night	16% 9% 4 8% 5% 5% 5% 4 5% 6% 34%	5467
April	1st to 10th	Night	15% 9% 3 6% 5% 4 5% 4 6% 7% 36%	2045
	11th to 20th	Night	14% 8% 3 7% 4 3 5% 3 6% 7% 41%	1928
	21st to end	Night	16% 7% 2 7% 4 4 4 3 7% 8% 36%	1800
May	1st to 10th	Night	20% 11% 3 8% 5% 4 5% 4 6% 7% 28%	4033
	11th to 20th	Night	16% 7% 3 7% 5% 4 5% 4 7% 10% 33%	4032
	21st to end	Night	12% 7% 3 7% 5% 5% 5% 4 6% 9% 38%	4421
June	1st to 10th	Night	8% 6% 2 5% 4 4 4 4 5% 9% 48%	1786
	11th to 20th	Night	8% 5% 2 6% 4 4 4 4 6% 11% 46%	1600
	21st to end	Night	6% 4 2 6% 4 5% 4 5% 7% 10% 48%	1600
July	1st to 10th	Night	8% 6% 2 6% 4 5% 4 4 6% 8% 47%	3618
	11th to 20th	Night	7% 6% 3 7% 4 5% 5% 5% 7% 10% 42%	3793
	21st to end	Night	9% 6% 2 6% 4 5% 5% 5% 7% 11% 39%	4427
August	1st to 10th	Night	6% 6% 3 7% 5% 4 4 5% 6% 9% 45%	2915
	11th to 20th	Night	6% 5% 3 7% 4 4 4 4 7% 8% 46%	2875
	21st to end	Night	4 2 1 4 3 3 4 3 6% 9% 60%	3577
September	1st to 10th	Night	11% 6% 2 4 3 3 4 3 5% 7% 53%	2095
	11th to 20th	Night	8% 4 2 5% 3 3 4 3 5% 7% 55%	2200
	21st to end	Night	15% 6% 2 6% 4 3 3 3 4 5% 49%	2200
October	1st to 10th	Night	8% 4 2 6% 3 4 4 3 4 7% 56%	2200
	11th to 20th	Night	14% 6% 2 6% 3 4 4 3 4 7% 46%	2359
	21st to end	Night	18% 8% 3 5% 4 4 4 3 5% 6% 41%	2797
November	1st to 10th	Night	12% 7% 3 6% 3 3 4 3 5% 6% 47%	2666
	11th to 20th	Night	15% 9% 2 8% 4 3 4 3 5% 6% 40%	2730
	21st to end	Night	19% 12% 3 8% 5% 4 4 3 4 6% 33%	2730
December	1st to 10th	Night	16% 11% 4 8% 4 4 3 3 4 5% 37%	4380
	11th to 20th	Night	19% 13% 6% 9% 5% 4 4 3 4 5% 27%	4952
	21st to end	Night	22% 18% 6% 12% 6% 4 4 3 4 5% 17%	6845

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	50% 21% 10% 15% 4	4692
	11th to 20th	Day	47% 22% 7% 11% 11% 1	5106
	21st to end	Day	52% 23% 7% 11% 5% 2	5780
February	1st to 10th	Day	23% 59% 4 8% 5%	2014
	11th to 20th	Day	23% 58% 3 10% 6%	2058
	21st to end	Day	21% 59% 5% 10% 5% 1	1730
March	1st to 10th	Day	43% 30% 3 11% 10% 2	4518
	11th to 20th	Day	27% 30% 6% 23% 13% 1	4980
	21st to end	Day	34% 30% 9% 15% 10% 2	5465
April	1st to 10th	Day	22% 63% 4 8% 4	2370
	11th to 20th	Day	18% 63% 4 10% 4 1	2419
	21st to end	Day	18% 62% 5% 10% 5% 1	2600
May	1st to 10th	Day	39% 32% 9% 12% 8%	5897
	11th to 20th	Day	36% 30% 9% 19% 6%	5865
	21st to end	Day	34% 32% 8% 17% 9% 1	6447
June	1st to 10th	Day	17% 63% 4 8% 8% 1	2608
	11th to 20th	Day	17% 63% 4 9% 7%	2800
	21st to end	Day	16% 62% 6% 8% 7% 1	2800
July	1st to 10th	Day	28% 28% 9% 20% 14% 1	6291
	11th to 20th	Day	30% 29% 11% 21% 10%	6083
	21st to end	Day	37% 29% 9% 13% 10% 1	6240
August	1st to 10th	Day	21% 38% 11% 23% 6%	4221
	11th to 20th	Day	22% 37% 8% 23% 9%	4213
	21st to end	Day	15% 37% 10% 22% 14% 1	4316
September	1st to 10th	Day	13% 57% 5% 13% 10% 2	2284
	11th to 20th	Day	13% 58% 6% 13% 10% 1	2200
	21st to end	Day	17% 57% 5% 12% 9% 1	2200
October	1st to 10th	Day	12% 36% 4 25% 22% 1	3590
	11th to 20th	Day	17% 36% 6% 20% 20% 1	3306
	21st to end	Day	20% 35% 6% 17% 20% 1	3277
November	1st to 10th	Day	21% 53% 6% 14% 6% 1	1852
	11th to 20th	Day	21% 54% 3 11% 9% 1	1890
	21st to end	Day	26% 55% 5% 10% 4	1890
December	1st to 10th	Day	30% 35% 6% 20% 9%	3020
	11th to 20th	Day	43% 32% 4 15% 5%	3460
	21st to end	Day	53% 27% 7% 9% 4	4340
January	1st to 10th	Night	51% 23% 8% 12% 6%	8233
	11th to 20th	Night	53% 21% 6% 10% 8% 2	7828
	21st to end	Night	43% 23% 8% 17% 8% 1	8401
February	1st to 10th	Night	23% 59% 4 9% 4	2604
	11th to 20th	Night	23% 58% 4 9% 5%	2459
	21st to end	Night	22% 59% 4 8% 6% 1	2076
March	1st to 10th	Night	39% 29% 4 20% 7% 2	5365
	11th to 20th	Night	25% 30% 7% 22% 15% 1	4980
	21st to end	Night	37% 30% 4 18% 9% 1	5467
April	1st to 10th	Night	22% 62% 4 8% 4	2045
	11th to 20th	Night	17% 62% 3 10% 6% 1	1928
	21st to end	Night	17% 62% 5% 9% 6% 1	1800
May	1st to 10th	Night	41% 32% 7% 13% 6% 2	4060
	11th to 20th	Night	33% 31% 10% 20% 5%	4033
	21st to end	Night	32% 32% 11% 16% 7% 2	4429
June	1st to 10th	Night	14% 62% 3 11% 9%	1786
	11th to 20th	Night	15% 63% 4 8% 8% 2	1600
	21st to end	Night	13% 62% 8% 10% 7% 1	1600
July	1st to 10th	Night	25% 29% 9% 19% 15% 3	3580
	11th to 20th	Night	28% 30% 12% 21% 10%	3748
	21st to end	Night	30% 29% 10% 18% 11% 2	4297
August	1st to 10th	Night	25% 39% 9% 22% 5% 1	2904
	11th to 20th	Night	23% 38% 7% 21% 11%	2902
	21st to end	Night	12% 37% 10% 25% 15% 1	3577
September	1st to 10th	Night	12% 58% 6% 12% 10% 2	2095
	11th to 20th	Night	11% 57% 4 12% 14% 1	2200
	21st to end	Night	16% 57% 5% 10% 12% 1	2200
October	1st to 10th	Night	12% 36% 3 18% 30% 1	3590
	11th to 20th	Night	13% 35% 7% 16% 27% 1	3832
	21st to end	Night	19% 36% 5% 15% 22% 3	4510
November	1st to 10th	Night	22% 54% 5% 10% 8% 1	2666
	11th to 20th	Night	20% 54% 4 12% 9% 2	2730
	21st to end	Night	27% 54% 5% 10% 4	2730
December	1st to 10th	Night	32% 34% 8% 17% 8%	4380
	11th to 20th	Night	42% 32% 7% 13% 5%	4954
	21st to end	Night	56% 27% 6% 10% 2	6845

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	27% 19% 34% 15% 5% 1	330
	11th to 20th	Day	30% 24% 30% 13% 3	330
	21st to end	Day	30% 21% 31% 14% 4	363
February	1st to 10th	Day	28% 21% 32% 16% 3	330
	11th to 20th	Day	29% 27% 32% 10% 2 1	330
	21st to end	Day	30% 17% 43% 9% 1	273
March	1st to 10th	Day	26% 28% 30% 14% 1	311
	11th to 20th	Day	27% 19% 31% 18% 5%	500
	21st to end	Day	32% 17% 30% 17% 5%	550
April	1st to 10th	Day	23% 18% 31% 18% 9% 1	500
	11th to 20th	Day	25% 19% 26% 18% 9% 3	492
	21st to end	Day	24% 15% 34% 16% 9% 2	500
May	1st to 10th	Day	26% 12% 31% 19% 8% 4	503
	11th to 20th	Day	23% 10% 28% 23% 10% 5%	527
	21st to end	Day	16% 7% 29% 25% 16% 8%	573
June	1st to 10th	Day	15% 6% 25% 29% 18% 7%	538
	11th to 20th	Day	12% 6% 26% 31% 19% 5%	730
	21st to end	Day	11% 7% 27% 30% 18% 8%	730
July	1st to 10th	Day	14% 3 18% 27% 24% 14%	721
	11th to 20th	Day	11% 4 24% 30% 21% 10%	633
	21st to end	Day	13% 2 16% 32% 23% 14%	576
August	1st to 10th	Day	10% 3 17% 29% 26% 15%	526
	11th to 20th	Day	12% 3 19% 31% 21% 13%	519
	21st to end	Day	10% 3 16% 30% 27% 13%	583
September	1st to 10th	Day	12% 4 16% 30% 28% 10%	530
	11th to 20th	Day	10% 3 14% 26% 32% 15%	530
	21st to end	Day	19% 7% 19% 24% 23% 8%	530
October	1st to 10th	Day	12% 6% 22% 31% 21% 8%	530
	11th to 20th	Day	15% 14% 31% 24% 13% 3	530
	21st to end	Day	24% 11% 38% 21% 5% 1	423
November	1st to 10th	Day	14% 17% 37% 21% 9% 2	330
	11th to 20th	Day	25% 22% 27% 18% 6% 1	330
	21st to end	Day	28% 15% 39% 14% 4	330
December	1st to 10th	Day	23% 20% 38% 14% 5% 1	330
	11th to 20th	Day	22% 19% 39% 14% 5%	330
	21st to end	Day	33% 15% 35% 14% 3 1	363
January	1st to 10th	Night	23% 17% 30% 25% 5%	1050
	11th to 20th	Night	28% 17% 32% 20% 3	897
	21st to end	Night	25% 15% 33% 24% 3	924
February	1st to 10th	Night	28% 12% 31% 27% 3	840
	11th to 20th	Night	24% 18% 32% 24% 3	823
	21st to end	Night	29% 14% 32% 23% 2	692
March	1st to 10th	Night	23% 14% 32% 25% 5%	809
	11th to 20th	Night	25% 14% 32% 24% 6% 1	800
	21st to end	Night	25% 13% 29% 26% 7%	880
April	1st to 10th	Night	20% 14% 32% 25% 9%	645
	11th to 20th	Night	20% 9% 32% 27% 10% 1	593
	21st to end	Night	19% 8% 38% 25% 10%	600
May	1st to 10th	Night	23% 7% 29% 28% 12% 1	600
	11th to 20th	Night	18% 6% 25% 32% 17% 2	591
	21st to end	Night	12% 3 23% 35% 24% 4	650
June	1st to 10th	Night	12% 3 20% 42% 21% 2	600
	11th to 20th	Night	12% 3 17% 42% 23% 3	600
	21st to end	Night	6% 3 24% 37% 27% 4	600
July	1st to 10th	Night	13% 1 12% 34% 32% 8%	585
	11th to 20th	Night	10% 1 16% 35% 33% 5%	582
	21st to end	Night	12% 1 12% 41% 30% 4	657
August	1st to 10th	Night	10% 2 11% 37% 37% 3	597
	11th to 20th	Night	9% 2 11% 42% 31% 5%	594
	21st to end	Night	7% 1 14% 33% 39% 6%	660
September	1st to 10th	Night	13% 3 14% 32% 35% 3	695
	11th to 20th	Night	10% 2 13% 34% 36% 5%	800
	21st to end	Night	18% 6% 19% 31% 24% 3	800
October	1st to 10th	Night	11% 4 22% 35% 24% 5%	800
	11th to 20th	Night	19% 9% 24% 31% 16% 2	800
	21st to end	Night	23% 9% 30% 26% 10% 1	880
November	1st to 10th	Night	18% 9% 29% 27% 16% 1	820
	11th to 20th	Night	22% 15% 28% 26% 10% 1	840
	21st to end	Night	27% 12% 25% 28% 9%	840
December	1st to 10th	Night	27% 12% 30% 26% 5%	840
	11th to 20th	Night	25% 11% 32% 26% 6% 1	840
	21st to end	Night	32% 13% 27% 23% 4	1019

Page generated at 2026-02-28 01:40:23. Version ac07

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