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 2025-02-21.

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	15% 9% 3 7% 5% 4 4 4 5% 7% 36%	109738
	Night	15% 10% 3 8% 5% 4 4 3 5% 7% 37%	108839
Transparency	Day	45% 5% 10% 23% 14% 2	113436
	Night	46% 5% 10% 22% 15% 2	113281
Seeing	Day	19% 13% 27% 22% 13% 5%	15599
	Night	19% 10% 27% 28% 14% 2	25184

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	15% 18% 9% 12% 4 4 3 3 3 4 25%	4032
	11th to 20th	Day	13% 15% 6% 13% 6% 6% 5% 3 3 4 25%	4060
	21st to end	Day	22% 12% 7% 8% 5% 5% 4 3 4 5% 24%	4466
February	1st to 10th	Day	20% 13% 5% 8% 4 4 4 3 4 4 30%	1895
	11th to 20th	Day	18% 11% 5% 11% 5% 4 4 3 4 5% 30%	1948
	21st to end	Day	19% 15% 6% 7% 5% 3 4 3 4 5% 30%	1570
March	1st to 10th	Day	23% 16% 4 9% 4 3 3 3 4 5% 26%	3169
	11th to 20th	Day	15% 8% 3 6% 4 4 4 4 5% 7% 40%	3480
	21st to end	Day	18% 10% 3 7% 4 4 4 3 5% 7% 36%	3815
April	1st to 10th	Day	16% 10% 3 7% 4 4 5% 4 5% 7% 35%	2224
	11th to 20th	Day	17% 8% 3 6% 4 4 4 3 4 7% 39%	2314
	21st to end	Day	17% 9% 3 8% 4 4 4 4 5% 7% 35%	2470
May	1st to 10th	Day	21% 10% 3 8% 5% 4 5% 4 5% 7% 30%	4082
	11th to 20th	Day	20% 8% 3 6% 4 3 4 3 5% 7% 36%	4081
	21st to end	Day	11% 6% 3 7% 5% 5% 6% 5% 8% 10% 34%	4476
June	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 5% 6% 7% 40%	2470
	11th to 20th	Day	9% 5% 2 6% 5% 4 4 4 7% 9% 44%	2609
	21st to end	Day	9% 6% 2 7% 6% 5% 6% 5% 6% 9% 40%	2660
July	1st to 10th	Day	12% 7% 3 7% 5% 4 5% 4 6% 10% 37%	4440
	11th to 20th	Day	7% 4 1 6% 4 5% 5% 4 7% 11% 46%	4202
	21st to end	Day	11% 7% 3 8% 6% 6% 6% 6% 7% 8% 31%	4466
August	1st to 10th	Day	9% 5% 2 5% 5% 5% 4 5% 7% 11% 42%	4104
	11th to 20th	Day	7% 6% 2 6% 5% 5% 5% 5% 7% 11% 41%	4044
	21st to end	Day	6% 4 2 5% 3 3 4 3 6% 8% 55%	4226
September	1st to 10th	Day	13% 6% 2 5% 3 3 4 4 5% 6% 48%	2152
	11th to 20th	Day	9% 5% 2 5% 3 4 4 4 7% 8% 48%	2090
	21st to end	Day	16% 6% 2 5% 4 4 3 2 4 6% 46%	2090
October	1st to 10th	Day	11% 5% 2 6% 3 4 4 4 5% 6% 50%	2090
	11th to 20th	Day	13% 7% 2 6% 4 3 4 3 5% 7% 46%	1920
	21st to end	Day	20% 8% 3 5% 3 3 4 3 4 6% 40%	1962
November	1st to 10th	Day	9% 8% 2 5% 4 3 4 2 4 6% 52%	1762
	11th to 20th	Day	14% 12% 4 8% 5% 3 4 3 4 6% 36%	1800
	21st to end	Day	18% 12% 4 8% 4 3 4 3 4 6% 36%	1800
December	1st to 10th	Day	19% 10% 4 6% 4 4 4 3 3 4 38%	2930
	11th to 20th	Day	19% 15% 5% 9% 5% 5% 4 3 4 4 26%	3373
	21st to end	Day	22% 19% 5% 10% 5% 4 4 3 4 5% 19%	4466
January	1st to 10th	Night	16% 17% 6% 14% 7% 4 5% 3 4 5% 19%	5889
	11th to 20th	Night	14% 16% 7% 13% 7% 5% 5% 3 4 4 22%	5900
	21st to end	Night	21% 13% 4 8% 5% 4 3 3 4 4 31%	6490
February	1st to 10th	Night	21% 13% 4 9% 4 5% 4 3 5% 5% 28%	2501
	11th to 20th	Night	19% 11% 4 9% 5% 4 5% 3 5% 6% 29%	2338
	21st to end	Night	21% 16% 5% 8% 4 3 3 3 4 6% 29%	1885
March	1st to 10th	Night	21% 15% 2 6% 3 4 4 3 4 6% 33%	3683
	11th to 20th	Night	14% 8% 3 6% 3 4 4 4 5% 6% 43%	3480
	21st to end	Night	16% 10% 3 7% 5% 4 3 4 5% 5% 39%	3817
April	1st to 10th	Night	15% 10% 2 7% 5% 4 5% 3 5% 8% 37%	1971
	11th to 20th	Night	15% 7% 2 6% 4 4 4 4 6% 7% 40%	1815
	21st to end	Night	17% 7% 4 7% 5% 4 4 3 6% 8% 37%	1710
May	1st to 10th	Night	22% 12% 3 8% 4 4 4 4 5% 6% 27%	2813
	11th to 20th	Night	18% 7% 2 5% 4 4 4 4 6% 8% 37%	2812
	21st to end	Night	10% 5% 2 5% 5% 4 4 4 7% 9% 45%	3079
June	1st to 10th	Night	9% 5% 2 4 5% 5% 4 3 6% 9% 48%	1710
	11th to 20th	Night	8% 5% 2 5% 4 4 4 4 6% 11% 49%	1565
	21st to end	Night	6% 5% 2 5% 4 4 6% 4 8% 10% 46%	1520
July	1st to 10th	Night	10% 5% 2 5% 4 4 4 3 6% 8% 49%	2530
	11th to 20th	Night	6% 4 2 5% 4 5% 4 4 5% 9% 51%	2742
	21st to end	Night	11% 6% 2 8% 5% 5% 4 5% 7% 10% 36%	3087
August	1st to 10th	Night	7% 6% 2 7% 5% 4 5% 3 7% 8% 45%	2825
	11th to 20th	Night	9% 7% 2 7% 4 4 4 3 6% 9% 44%	2785
	21st to end	Night	4 2 1 4 3 3 4 3 6% 10% 60%	3426
September	1st to 10th	Night	12% 6% 1 4 3 3 3 3 6% 6% 52%	2009
	11th to 20th	Night	8% 4 2 6% 4 3 5% 3 5% 7% 53%	2090
	21st to end	Night	15% 5% 2 5% 4 4 4 3 4 6% 49%	2090
October	1st to 10th	Night	8% 4 2 6% 4 4 3 3 5% 7% 55%	2090
	11th to 20th	Night	14% 7% 2 5% 3 4 4 4 4 7% 45%	2258
	21st to end	Night	18% 8% 3 6% 4 3 3 3 5% 5% 42%	2631
November	1st to 10th	Night	14% 7% 2 5% 4 3 4 3 5% 6% 47%	2536
	11th to 20th	Night	16% 9% 2 7% 4 3 4 3 5% 7% 39%	2600
	21st to end	Night	18% 13% 3 7% 5% 4 4 4 4 6% 33%	2600
December	1st to 10th	Night	17% 12% 4 7% 4 3 3 2 4 5% 38%	4250
	11th to 20th	Night	19% 15% 6% 9% 5% 4 4 3 4 6% 26%	4822
	21st to end	Night	22% 19% 6% 10% 6% 4 4 3 4 4 17%	6490

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	64% 3 9% 17% 7%	4033
	11th to 20th	Day	61% 6% 7% 14% 11% 2	4060
	21st to end	Day	62% 3 8% 18% 7% 2	4466
February	1st to 10th	Day	57% 4 9% 19% 10% 1	1895
	11th to 20th	Day	57% 4 8% 18% 11% 1	1958
	21st to end	Day	56% 4 9% 20% 9% 2	1570
March	1st to 10th	Day	58% 6% 8% 18% 8% 1	3169
	11th to 20th	Day	42% 5% 10% 25% 16% 1	3480
	21st to end	Day	48% 5% 11% 24% 11% 1	3815
April	1st to 10th	Day	47% 5% 10% 24% 13% 1	2224
	11th to 20th	Day	45% 5% 9% 23% 14% 3	2314
	21st to end	Day	49% 5% 11% 22% 12% 2	2470
May	1st to 10th	Day	53% 5% 12% 21% 8% 1	4120
	11th to 20th	Day	47% 6% 13% 22% 12% 1	4085
	21st to end	Day	41% 8% 14% 20% 16% 2	4489
June	1st to 10th	Day	40% 7% 11% 24% 16% 2	2470
	11th to 20th	Day	35% 7% 15% 25% 18% 1	2609
	21st to end	Day	39% 6% 14% 23% 14% 4	2660
July	1st to 10th	Day	41% 6% 11% 21% 19% 1	4371
	11th to 20th	Day	31% 6% 11% 34% 17% 1	4130
	21st to end	Day	47% 7% 13% 19% 13% 2	4324
August	1st to 10th	Day	33% 7% 15% 33% 11% 1	4091
	11th to 20th	Day	35% 6% 12% 32% 15%	4083
	21st to end	Day	26% 5% 15% 30% 21% 3	4225
September	1st to 10th	Day	36% 4 12% 24% 20% 5%	2152
	11th to 20th	Day	31% 5% 12% 26% 22% 3	2090
	21st to end	Day	40% 3 9% 24% 21% 2	2090
October	1st to 10th	Day	23% 4 8% 32% 32% 2	3480
	11th to 20th	Day	30% 3 8% 30% 27% 2	3173
	21st to end	Day	35% 3 10% 26% 23% 3	3212
November	1st to 10th	Day	35% 3 10% 28% 21% 3	1762
	11th to 20th	Day	48% 4 7% 22% 16% 3	1800
	21st to end	Day	51% 3 9% 23% 14% 1	1800
December	1st to 10th	Day	51% 3 9% 27% 10%	2930
	11th to 20th	Day	61% 5% 7% 19% 8%	3370
	21st to end	Day	68% 4 9% 13% 6% 1	4466
January	1st to 10th	Night	67% 5% 7% 14% 7%	5889
	11th to 20th	Night	66% 4 8% 12% 8% 3	5900
	21st to end	Night	56% 4 7% 21% 10% 1	6490
February	1st to 10th	Night	58% 3 10% 20% 8% 1	2501
	11th to 20th	Night	56% 3 8% 19% 11% 1	2339
	21st to end	Night	57% 3 10% 17% 10% 2	1885
March	1st to 10th	Night	54% 4 7% 23% 11% 1	3683
	11th to 20th	Night	39% 6% 10% 27% 15% 1	3480
	21st to end	Night	47% 5% 8% 28% 12% 1	3817
April	1st to 10th	Night	44% 6% 10% 25% 12% 2	1971
	11th to 20th	Night	41% 5% 9% 20% 18% 6%	1815
	21st to end	Night	46% 5% 11% 22% 13% 3	1710
May	1st to 10th	Night	56% 6% 9% 19% 8% 2	2840
	11th to 20th	Night	43% 7% 14% 26% 9% 1	2813
	21st to end	Night	32% 7% 15% 27% 14% 4	3087
June	1st to 10th	Night	32% 6% 12% 27% 20% 3	1710
	11th to 20th	Night	30% 6% 16% 23% 21% 4	1565
	21st to end	Night	29% 9% 17% 23% 17% 5%	1520
July	1st to 10th	Night	34% 6% 11% 24% 19% 6%	2490
	11th to 20th	Night	29% 5% 13% 31% 20% 2	2692
	21st to end	Night	42% 6% 13% 22% 13% 4	2988
August	1st to 10th	Night	33% 7% 14% 32% 12% 1	2814
	11th to 20th	Night	37% 6% 10% 28% 19% 1	2812
	21st to end	Night	20% 5% 16% 33% 23% 3	3426
September	1st to 10th	Night	31% 6% 11% 26% 20% 7%	2009
	11th to 20th	Night	30% 6% 10% 24% 27% 3	2090
	21st to end	Night	37% 4 9% 22% 26% 2	2090
October	1st to 10th	Night	22% 3 7% 27% 38% 3	3480
	11th to 20th	Night	28% 3 8% 27% 32% 2	3744
	21st to end	Night	33% 3 8% 23% 28% 5%	4331
November	1st to 10th	Night	38% 4 9% 22% 23% 4	2536
	11th to 20th	Night	46% 3 8% 21% 19% 4	2600
	21st to end	Night	54% 3 10% 21% 11% 2	2600
December	1st to 10th	Night	50% 3 11% 25% 11%	4250
	11th to 20th	Night	59% 4 11% 18% 7% 1	4824
	21st to end	Night	70% 4 8% 14% 4	6490

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% 31% 13% 3	300
	11th to 20th	Day	30% 28% 33% 7% 1	300
	21st to end	Day	32% 23% 32% 11% 2	330
February	1st to 10th	Day	31% 23% 33% 11% 1	300
	11th to 20th	Day	34% 28% 30% 7% 1	300
	21st to end	Day	34% 23% 37% 6%	225
March	1st to 10th	Day	27% 32% 29% 11% 1	293
	11th to 20th	Day	27% 20% 32% 15% 5%	460
	21st to end	Day	34% 17% 29% 14% 5%	506
April	1st to 10th	Day	24% 19% 30% 19% 7% 1	460
	11th to 20th	Day	24% 21% 27% 17% 8% 3	452
	21st to end	Day	24% 19% 32% 14% 8% 2	460
May	1st to 10th	Day	26% 19% 30% 16% 6% 4	463
	11th to 20th	Day	22% 13% 28% 22% 10% 5%	487
	21st to end	Day	14% 8% 27% 28% 14% 8%	529
June	1st to 10th	Day	13% 10% 24% 29% 17% 7%	490
	11th to 20th	Day	11% 7% 25% 31% 20% 6%	629
	21st to end	Day	10% 7% 28% 31% 18% 7%	680
July	1st to 10th	Day	14% 5% 18% 27% 20% 17%	671
	11th to 20th	Day	9% 5% 23% 30% 23% 9%	537
	21st to end	Day	11% 4 19% 31% 24% 11%	532
August	1st to 10th	Day	12% 4 15% 30% 24% 15%	486
	11th to 20th	Day	11% 6% 22% 31% 22% 9%	479
	21st to end	Day	8% 6% 15% 31% 27% 14%	539
September	1st to 10th	Day	12% 6% 18% 29% 26% 10%	490
	11th to 20th	Day	11% 3 17% 27% 30% 12%	490
	21st to end	Day	21% 9% 22% 23% 19% 7%	490
October	1st to 10th	Day	10% 6% 28% 31% 18% 6%	490
	11th to 20th	Day	17% 14% 31% 22% 12% 3	490
	21st to end	Day	25% 12% 39% 19% 6%	411
November	1st to 10th	Day	14% 18% 36% 20% 9% 3	300
	11th to 20th	Day	24% 21% 31% 17% 5% 2	300
	21st to end	Day	25% 20% 38% 14% 3	300
December	1st to 10th	Day	26% 20% 35% 14% 5%	300
	11th to 20th	Day	24% 23% 38% 11% 4	300
	21st to end	Day	32% 20% 36% 11% 2	330
January	1st to 10th	Night	23% 21% 33% 20% 4	800
	11th to 20th	Night	29% 18% 33% 17% 3	800
	21st to end	Night	24% 18% 35% 21% 3	880
February	1st to 10th	Night	29% 13% 35% 22% 2	800
	11th to 20th	Night	26% 20% 33% 20% 1	783
	21st to end	Night	29% 16% 36% 18% 1	629
March	1st to 10th	Night	22% 18% 32% 22% 5%	760
	11th to 20th	Night	25% 15% 33% 21% 6% 1	760
	21st to end	Night	25% 11% 32% 25% 7%	836
April	1st to 10th	Night	21% 13% 34% 25% 7%	641
	11th to 20th	Night	20% 10% 34% 24% 11% 1	563
	21st to end	Night	18% 10% 39% 24% 8% 1	570
May	1st to 10th	Night	21% 10% 30% 26% 11% 1	570
	11th to 20th	Night	18% 5% 25% 33% 17% 2	561
	21st to end	Night	10% 3 24% 35% 24% 5%	617
June	1st to 10th	Night	10% 4 21% 40% 24% 1	570
	11th to 20th	Night	10% 3 16% 43% 25% 3	570
	21st to end	Night	7% 3 24% 39% 24% 3	570
July	1st to 10th	Night	11% 2 13% 32% 33% 8%	555
	11th to 20th	Night	7% 2 18% 34% 36% 4	552
	21st to end	Night	11% 4 12% 38% 33% 3	624
August	1st to 10th	Night	10% 2 11% 38% 36% 3	567
	11th to 20th	Night	10% 3 12% 42% 29% 5%	564
	21st to end	Night	7% 1 13% 36% 37% 6%	627
September	1st to 10th	Night	13% 4 14% 34% 31% 5%	679
	11th to 20th	Night	9% 3 16% 33% 33% 6%	760
	21st to end	Night	16% 6% 22% 33% 21% 3	760
October	1st to 10th	Night	11% 5% 23% 36% 22% 3	760
	11th to 20th	Night	17% 9% 28% 31% 14% 1	760
	21st to end	Night	23% 9% 34% 23% 11%	836
November	1st to 10th	Night	17% 11% 30% 26% 15% 1	780
	11th to 20th	Night	20% 17% 30% 24% 9% 1	800
	21st to end	Night	26% 12% 28% 27% 7% 1	800
December	1st to 10th	Night	27% 14% 33% 22% 5%	800
	11th to 20th	Night	26% 13% 34% 22% 5% 1	800
	21st to end	Night	30% 15% 32% 20% 3	880

Page generated at 2025-02-18 03:26:29. Version ac07

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