Cincinnati Nature Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cincinnati Nature Center clear sky chart from 2005-11-06 to 2026-06-16.

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% 4 5% 4 5% 7% 35%	138315
	Night	15% 10% 3 8% 5% 4 4 3 5% 7% 36%	133712
Transparency	Day	46% 5% 10% 23% 14% 2	141969
	Night	46% 5% 10% 22% 15% 2	138131
Seeing	Day	19% 14% 27% 21% 13% 5%	17400
	Night	19% 10% 27% 28% 14% 2	26878

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	17% 16% 7% 11% 5% 4 3 3 3 5% 25%	5234
	11th to 20th	Day	12% 13% 6% 15% 6% 6% 4 3 3 4 27%	5280
	21st to end	Day	19% 12% 6% 10% 7% 6% 5% 3 5% 6% 21%	5780
February	1st to 10th	Day	20% 13% 5% 8% 4 4 4 3 5% 4 30%	1990
	11th to 20th	Day	17% 11% 5% 11% 5% 4 4 3 4 5% 30%	2048
	21st to end	Day	18% 14% 6% 7% 5% 3 4 3 4 6% 31%	1730
March	1st to 10th	Day	18% 15% 5% 10% 4 3 3 3 4 5% 31%	4644
	11th to 20th	Day	14% 8% 3 7% 5% 4 4 4 6% 8% 38%	5090
	21st to end	Day	17% 10% 3 7% 4 4 4 3 5% 7% 34%	5586
April	1st to 10th	Day	16% 9% 3 7% 4 4 5% 4 6% 7% 35%	2458
	11th to 20th	Day	16% 8% 3 6% 5% 4 4 3 5% 7% 39%	2560
	21st to end	Day	17% 8% 3 8% 5% 4 4 4 5% 7% 36%	2730
May	1st to 10th	Day	18% 9% 3 8% 5% 5% 5% 5% 6% 7% 30%	7616
	11th to 20th	Day	17% 8% 3 7% 4 4 5% 4 5% 7% 36%	7626
	21st to end	Day	17% 8% 3 8% 5% 5% 5% 5% 7% 9% 27%	8391
June	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 5% 6% 7% 40%	2730
	11th to 20th	Day	9% 6% 2 6% 5% 4 4 4 7% 10% 42%	2815
	21st to end	Day	8% 6% 2 7% 6% 6% 6% 5% 7% 9% 40%	2800
July	1st to 10th	Day	10% 6% 3 6% 5% 4 5% 4 6% 10% 41%	6360
	11th to 20th	Day	9% 6% 2 7% 5% 5% 6% 5% 7% 11% 36%	6024
	21st to end	Day	10% 8% 3 9% 6% 6% 6% 6% 7% 8% 31%	6424
August	1st to 10th	Day	9% 5% 2 5% 5% 5% 4 5% 7% 11% 43%	4234
	11th to 20th	Day	7% 6% 2 7% 4 5% 5% 5% 7% 11% 41%	4174
	21st to end	Day	6% 4 2 5% 3 3 4 3 6% 9% 55%	4360
September	1st to 10th	Day	12% 6% 2 5% 3 4 4 4 5% 6% 49%	2265
	11th to 20th	Day	8% 5% 2 5% 3 4 5% 4 6% 8% 50%	2200
	21st to end	Day	16% 7% 2 5% 4 4 3 2 4 7% 46%	2200
October	1st to 10th	Day	11% 5% 1 5% 3 4 4 4 5% 6% 50%	2200
	11th to 20th	Day	13% 6% 2 6% 4 3 4 3 5% 7% 47%	2021
	21st to end	Day	20% 8% 2 6% 3 3 4 3 4 6% 40%	2065
November	1st to 10th	Day	10% 8% 2 5% 4 3 4 3 4 6% 51%	1852
	11th to 20th	Day	14% 12% 4 8% 5% 3 4 3 4 6% 36%	1890
	21st to end	Day	18% 12% 4 8% 4 3 4 3 3 6% 35%	1890
December	1st to 10th	Day	19% 11% 4 7% 4 4 4 3 3 4 37%	3020
	11th to 20th	Day	19% 15% 5% 10% 5% 5% 4 3 4 4 26%	3463
	21st to end	Day	22% 19% 5% 10% 5% 4 4 3 4 5% 19%	4565
January	1st to 10th	Night	14% 16% 5% 13% 7% 5% 5% 4 5% 6% 21%	7635
	11th to 20th	Night	12% 15% 7% 15% 7% 5% 5% 3 3 4 24%	7680
	21st to end	Night	18% 12% 4 9% 6% 5% 3 3 4 5% 31%	8401
February	1st to 10th	Night	20% 12% 4 9% 4 5% 4 3 5% 6% 28%	2626
	11th to 20th	Night	19% 11% 4 9% 5% 4 5% 3 5% 6% 30%	2458
	21st to end	Night	19% 15% 5% 8% 3 3 3 3 4 6% 30%	2076
March	1st to 10th	Night	18% 15% 2 6% 4 4 3 3 4 5% 37%	5428
	11th to 20th	Night	13% 8% 3 6% 4 4 5% 4 6% 7% 42%	5090
	21st to end	Night	17% 11% 4 8% 5% 4 4 4 5% 6% 33%	5588
April	1st to 10th	Night	16% 10% 2 7% 4 4 5% 3 5% 8% 37%	2179
	11th to 20th	Night	15% 7% 2 6% 4 4 5% 5% 6% 7% 40%	2008
	21st to end	Night	16% 8% 4 7% 4 4 4 3 6% 8% 37%	1890
May	1st to 10th	Night	20% 9% 3 7% 4 4 5% 4 6% 8% 31%	5237
	11th to 20th	Night	15% 7% 2 7% 4 5% 5% 5% 7% 8% 36%	5234
	21st to end	Night	16% 8% 3 8% 5% 5% 5% 4 7% 8% 32%	5761
June	1st to 10th	Night	9% 5% 2 4 4 5% 4 3 6% 9% 48%	1890
	11th to 20th	Night	9% 5% 1 5% 4 4 4 4 6% 10% 48%	1689
	21st to end	Night	6% 5% 2 5% 4 4 5% 4 8% 10% 46%	1600
July	1st to 10th	Night	9% 5% 2 6% 4 4 4 4 6% 8% 48%	3618
	11th to 20th	Night	8% 6% 2 6% 5% 5% 5% 4 6% 10% 42%	3920
	21st to end	Night	10% 6% 2 8% 5% 5% 5% 4 7% 10% 38%	4427
August	1st to 10th	Night	7% 6% 2 7% 5% 4 5% 4 7% 8% 45%	2915
	11th to 20th	Night	9% 7% 2 7% 4 4 4 3 6% 9% 45%	2875
	21st to end	Night	4 2 1 4 3 3 4 3 6% 10% 60%	3534
September	1st to 10th	Night	11% 5% 1 4 3 3 3 3 6% 6% 53%	2115
	11th to 20th	Night	8% 4 2 6% 4 4 5% 4 5% 7% 53%	2200
	21st to end	Night	15% 5% 2 5% 4 4 4 3 4 6% 48%	2200
October	1st to 10th	Night	9% 4 2 6% 4 4 4 3 5% 7% 55%	2200
	11th to 20th	Night	14% 6% 2 6% 4 4 4 4 5% 7% 46%	2377
	21st to end	Night	19% 8% 3 6% 4 3 3 3 5% 5% 42%	2770
November	1st to 10th	Night	14% 7% 3 5% 4 3 4 3 5% 6% 47%	2666
	11th to 20th	Night	16% 9% 2 7% 4 3 4 3 5% 7% 40%	2730
	21st to end	Night	18% 14% 4 7% 5% 4 3 3 4 6% 32%	2730
December	1st to 10th	Night	17% 12% 4 8% 5% 3 3 2 4 5% 37%	4380
	11th to 20th	Night	19% 15% 6% 9% 5% 4 3 3 4 6% 26%	4952
	21st to end	Night	22% 19% 6% 10% 6% 4 4 3 4 4 17%	6633

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	63% 3 11% 17% 6%	5235
	11th to 20th	Day	59% 5% 7% 14% 13% 2	5280
	21st to end	Day	64% 3 8% 16% 6% 2	5780
February	1st to 10th	Day	57% 4 9% 20% 10% 1	1990
	11th to 20th	Day	57% 4 9% 19% 11% 1	2058
	21st to end	Day	55% 3 10% 21% 9% 2	1730
March	1st to 10th	Day	55% 5% 7% 19% 12% 3	4644
	11th to 20th	Day	44% 4 9% 27% 15% 1	5090
	21st to end	Day	49% 5% 11% 21% 12% 2	5586
April	1st to 10th	Day	46% 5% 11% 23% 13% 1	2458
	11th to 20th	Day	46% 5% 9% 23% 14% 3	2560
	21st to end	Day	48% 5% 11% 23% 12% 2	2730
May	1st to 10th	Day	51% 6% 11% 21% 11% 1	7651
	11th to 20th	Day	47% 5% 11% 24% 13%	7630
	21st to end	Day	50% 7% 11% 19% 11% 2	8405
June	1st to 10th	Day	40% 7% 11% 23% 17% 2	2730
	11th to 20th	Day	35% 7% 15% 24% 17% 1	2815
	21st to end	Day	39% 6% 14% 23% 14% 4	2800
July	1st to 10th	Day	38% 6% 11% 25% 19% 1	6291
	11th to 20th	Day	39% 8% 13% 27% 13% 1	5952
	21st to end	Day	46% 8% 12% 20% 13% 2	6240
August	1st to 10th	Day	33% 7% 15% 34% 11% 1	4221
	11th to 20th	Day	35% 6% 12% 32% 15%	4213
	21st to end	Day	26% 5% 14% 30% 21% 3	4359
September	1st to 10th	Day	35% 4 11% 24% 20% 5%	2265
	11th to 20th	Day	31% 5% 11% 26% 24% 3	2200
	21st to end	Day	40% 4 9% 24% 22% 2	2200
October	1st to 10th	Day	23% 3 7% 32% 32% 2	3590
	11th to 20th	Day	29% 3 8% 30% 27% 2	3274
	21st to end	Day	35% 3 10% 25% 23% 3	3315
November	1st to 10th	Day	36% 3 10% 28% 21% 3	1852
	11th to 20th	Day	48% 4 7% 22% 15% 3	1890
	21st to end	Day	52% 3 8% 22% 14% 1	1890
December	1st to 10th	Day	51% 3 9% 27% 10%	3020
	11th to 20th	Day	61% 5% 7% 19% 8%	3460
	21st to end	Day	68% 4 9% 13% 6% 1	4565
January	1st to 10th	Night	63% 5% 9% 15% 7%	7636
	11th to 20th	Night	64% 4 7% 13% 10% 3	7680
	21st to end	Night	56% 4 9% 21% 10% 1	8401
February	1st to 10th	Night	57% 3 10% 20% 8% 1	2626
	11th to 20th	Night	56% 3 9% 20% 11% 1	2459
	21st to end	Night	56% 3 11% 18% 10% 2	2076
March	1st to 10th	Night	51% 3 6% 27% 11% 2	5428
	11th to 20th	Night	40% 5% 9% 29% 16% 1	5090
	21st to end	Night	52% 4 7% 24% 12% 2	5588
April	1st to 10th	Night	45% 6% 11% 24% 12% 2	2179
	11th to 20th	Night	41% 5% 10% 21% 17% 5%	2008
	21st to end	Night	45% 4 11% 24% 13% 3	1890
May	1st to 10th	Night	50% 6% 10% 22% 9% 2	5264
	11th to 20th	Night	44% 7% 13% 23% 13% 1	5235
	21st to end	Night	47% 6% 13% 19% 10% 4	5771
June	1st to 10th	Night	32% 6% 12% 25% 22% 2	1890
	11th to 20th	Night	31% 6% 15% 23% 21% 4	1689
	21st to end	Night	29% 9% 17% 23% 17% 5%	1600
July	1st to 10th	Night	34% 6% 11% 24% 21% 4	3580
	11th to 20th	Night	37% 7% 14% 26% 15% 1	3873
	21st to end	Night	40% 6% 13% 24% 14% 3	4297
August	1st to 10th	Night	33% 7% 14% 33% 12% 1	2904
	11th to 20th	Night	36% 6% 10% 28% 18% 1	2902
	21st to end	Night	20% 5% 16% 33% 23% 3	3534
September	1st to 10th	Night	30% 5% 11% 26% 21% 6%	2115
	11th to 20th	Night	30% 5% 9% 24% 28% 3	2200
	21st to end	Night	37% 4 9% 21% 26% 2	2200
October	1st to 10th	Night	22% 3 7% 26% 38% 3	3590
	11th to 20th	Night	28% 3 8% 26% 32% 3	3863
	21st to end	Night	34% 3 8% 23% 28% 5%	4470
November	1st to 10th	Night	38% 4 9% 23% 23% 3	2666
	11th to 20th	Night	45% 3 8% 22% 18% 3	2730
	21st to end	Night	54% 3 9% 21% 11% 1	2730
December	1st to 10th	Night	51% 3 11% 24% 10%	4380
	11th to 20th	Night	60% 4 11% 18% 7% 1	4954
	21st to end	Night	70% 4 8% 14% 4	6633

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% 32% 13% 4	330
	11th to 20th	Day	32% 28% 32% 6% 1	330
	21st to end	Day	33% 23% 31% 11% 2	363
February	1st to 10th	Day	30% 22% 34% 12% 2	330
	11th to 20th	Day	33% 28% 32% 7% 1	330
	21st to end	Day	30% 24% 39% 6%	273
March	1st to 10th	Day	28% 30% 30% 10% 1	355
	11th to 20th	Day	29% 21% 32% 15% 4	540
	21st to end	Day	34% 18% 30% 14% 4	594
April	1st to 10th	Day	25% 19% 32% 18% 6% 1	540
	11th to 20th	Day	24% 21% 29% 17% 7% 3	532
	21st to end	Day	24% 19% 32% 15% 8% 2	540
May	1st to 10th	Day	26% 20% 30% 15% 6% 3	543
	11th to 20th	Day	22% 13% 29% 22% 9% 4	567
	21st to end	Day	17% 9% 28% 26% 13% 7%	617
June	1st to 10th	Day	13% 9% 26% 28% 17% 7%	570
	11th to 20th	Day	12% 7% 26% 31% 19% 5%	700
	21st to end	Day	9% 7% 27% 31% 19% 8%	730
July	1st to 10th	Day	14% 4 17% 27% 22% 16%	721
	11th to 20th	Day	9% 5% 23% 30% 24% 9%	580
	21st to end	Day	11% 4 18% 32% 24% 11%	576
August	1st to 10th	Day	11% 4 16% 30% 24% 15%	526
	11th to 20th	Day	10% 5% 20% 30% 24% 9%	519
	21st to end	Day	8% 6% 16% 31% 26% 13%	583
September	1st to 10th	Day	12% 6% 17% 28% 27% 9%	530
	11th to 20th	Day	10% 3 16% 26% 31% 14%	530
	21st to end	Day	20% 8% 22% 22% 20% 7%	530
October	1st to 10th	Day	10% 6% 28% 30% 20% 7%	530
	11th to 20th	Day	16% 14% 31% 23% 13% 3	530
	21st to end	Day	25% 13% 38% 19% 5%	448
November	1st to 10th	Day	15% 18% 35% 20% 9% 2	330
	11th to 20th	Day	25% 22% 31% 16% 4 2	330
	21st to end	Day	27% 19% 38% 13% 2	330
December	1st to 10th	Day	25% 21% 36% 13% 4	330
	11th to 20th	Day	24% 24% 38% 11% 4	330
	21st to end	Day	32% 20% 35% 11% 1	363
January	1st to 10th	Night	23% 20% 33% 20% 4	840
	11th to 20th	Night	29% 19% 33% 16% 3	840
	21st to end	Night	24% 18% 35% 20% 3	924
February	1st to 10th	Night	28% 13% 35% 23% 2	840
	11th to 20th	Night	26% 20% 32% 20% 1	823
	21st to end	Night	27% 16% 37% 18% 1	692
March	1st to 10th	Night	23% 18% 32% 22% 5%	840
	11th to 20th	Night	25% 15% 33% 21% 6% 1	840
	21st to end	Night	24% 13% 32% 24% 6%	924
April	1st to 10th	Night	22% 13% 34% 24% 6%	709
	11th to 20th	Night	20% 10% 35% 24% 10% 1	623
	21st to end	Night	18% 10% 39% 24% 8% 1	630
May	1st to 10th	Night	21% 10% 31% 26% 10% 1	630
	11th to 20th	Night	18% 6% 26% 32% 16% 2	621
	21st to end	Night	11% 3 25% 34% 22% 4	683
June	1st to 10th	Night	10% 3 22% 40% 23% 1	630
	11th to 20th	Night	12% 4 16% 42% 24% 3	615
	21st to end	Night	7% 3 23% 39% 26% 3	600
July	1st to 10th	Night	11% 2 13% 32% 34% 8%	585
	11th to 20th	Night	7% 2 18% 34% 35% 3	582
	21st to end	Night	11% 3 12% 37% 34% 3	657
August	1st to 10th	Night	9% 3 12% 38% 35% 3	597
	11th to 20th	Night	9% 3 12% 41% 30% 5%	594
	21st to end	Night	7% 1 14% 37% 36% 6%	660
September	1st to 10th	Night	13% 4 14% 35% 31% 4	715
	11th to 20th	Night	9% 3 16% 33% 33% 6%	800
	21st to end	Night	16% 6% 22% 32% 22% 3	800
October	1st to 10th	Night	11% 5% 22% 36% 22% 3	800
	11th to 20th	Night	16% 9% 27% 33% 13% 1	800
	21st to end	Night	23% 10% 34% 23% 10%	880
November	1st to 10th	Night	17% 10% 31% 26% 15% 1	820
	11th to 20th	Night	20% 18% 30% 23% 9% 1	840
	21st to end	Night	27% 12% 27% 27% 7% 1	840
December	1st to 10th	Night	26% 14% 33% 22% 4	840
	11th to 20th	Night	25% 13% 35% 22% 5% 1	840
	21st to end	Night	30% 16% 31% 20% 3	924

Page generated at 2026-06-13 02:31:38. Version ac07

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