Buckeyestargazer Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Buckeyestargazer Observatory 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	13% 9% 3 8% 5% 5% 4 4 6% 7% 35%	119214
	Night	14% 10% 4 8% 5% 4 4 4 5% 6% 36%	119177
Transparency	Day	46% 5% 12% 22% 13% 2	122798
	Night	48% 5% 11% 21% 14% 2	123721
Seeing	Day	17% 11% 29% 24% 14% 5%	16511
	Night	18% 10% 30% 29% 12% 1	26436

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% 12% 8% 15% 6% 5% 5% 4 6% 6% 20%	3617
	11th to 20th	Day	12% 12% 6% 14% 7% 7% 5% 5% 6% 4 20%	3620
	21st to end	Day	18% 18% 5% 9% 5% 3 4 3 4 6% 25%	3982
February	1st to 10th	Day	15% 15% 4 12% 6% 6% 5% 3 4 6% 24%	1932
	11th to 20th	Day	14% 11% 5% 9% 6% 5% 4 4 5% 7% 30%	1948
	21st to end	Day	16% 14% 4 10% 4 4 5% 3 6% 6% 28%	1650
March	1st to 10th	Day	18% 13% 4 9% 4 3 3 2 4 4 35%	4480
	11th to 20th	Day	8% 9% 4 7% 4 4 5% 4 6% 7% 41%	4700
	21st to end	Day	18% 13% 6% 11% 6% 6% 5% 4 5% 6% 21%	5872
April	1st to 10th	Day	17% 11% 3 8% 5% 4 4 4 6% 7% 30%	2400
	11th to 20th	Day	17% 10% 3 6% 5% 5% 3 3 5% 7% 36%	2374
	21st to end	Day	19% 8% 3 7% 4 4 4 4 5% 7% 34%	2556
May	1st to 10th	Day	18% 7% 3 7% 5% 5% 6% 4 6% 8% 32%	5862
	11th to 20th	Day	14% 7% 3 6% 5% 5% 5% 4 6% 9% 39%	5923
	21st to end	Day	13% 7% 3 6% 4 4 4 3 6% 8% 41%	6935
June	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 4 6% 8% 44%	2787
	11th to 20th	Day	8% 5% 2 6% 4 4 5% 4 7% 8% 45%	2660
	21st to end	Day	10% 6% 2 7% 5% 5% 6% 4 7% 9% 39%	2660
July	1st to 10th	Day	12% 7% 2 7% 6% 5% 5% 5% 7% 10% 35%	4440
	11th to 20th	Day	7% 4 2 5% 5% 5% 4 4 7% 10% 47%	4440
	21st to end	Day	8% 6% 3 7% 5% 5% 5% 4 7% 8% 42%	4813
August	1st to 10th	Day	7% 5% 2 6% 5% 4 5% 4 6% 9% 47%	4184
	11th to 20th	Day	8% 5% 2 6% 4 5% 5% 4 6% 8% 47%	3852
	21st to end	Day	7% 4 2 6% 4 4 4 4 6% 9% 49%	4180
September	1st to 10th	Day	10% 5% 2 6% 4 5% 4 4 6% 8% 47%	2280
	11th to 20th	Day	10% 6% 2 5% 4 4 4 4 6% 8% 48%	2109
	21st to end	Day	11% 7% 2 7% 5% 4 4 5% 6% 10% 41%	2090
October	1st to 10th	Day	11% 7% 3 7% 3 4 4 4 5% 7% 46%	2090
	11th to 20th	Day	18% 7% 3 8% 4 5% 4 4 6% 7% 36%	1871
	21st to end	Day	19% 9% 3 8% 5% 4 6% 4 5% 6% 30%	1881
November	1st to 10th	Day	12% 8% 2 6% 4 4 4 4 6% 8% 42%	1762
	11th to 20th	Day	18% 11% 3 8% 4 5% 4 3 5% 7% 31%	1800
	21st to end	Day	18% 12% 3 10% 6% 4 4 3 5% 5% 32%	1800
December	1st to 10th	Day	10% 13% 3 9% 6% 5% 4 4 5% 7% 35%	2674
	11th to 20th	Day	14% 15% 6% 13% 6% 5% 4 4 5% 7% 21%	3008
	21st to end	Day	26% 22% 6% 12% 5% 4 3 3 4 4 11%	3982
January	1st to 10th	Night	14% 15% 8% 13% 6% 5% 4 3 5% 5% 22%	6348
	11th to 20th	Night	13% 18% 7% 13% 7% 5% 5% 4 6% 4 19%	6360
	21st to end	Night	19% 15% 6% 9% 4 4 4 3 4 4 29%	6978
February	1st to 10th	Night	16% 14% 4 9% 6% 5% 4 3 5% 6% 29%	2466
	11th to 20th	Night	15% 11% 4 8% 6% 4 4 3 4 7% 34%	2338
	21st to end	Night	19% 13% 3 8% 4 4 4 4 4 5% 32%	1980
March	1st to 10th	Night	15% 11% 5% 8% 4 4 4 3 4 6% 36%	5373
	11th to 20th	Night	12% 7% 2 6% 4 4 4 3 5% 7% 45%	5259
	21st to end	Night	18% 10% 4 9% 5% 5% 5% 4 5% 6% 30%	5100
April	1st to 10th	Night	14% 8% 2 7% 5% 5% 5% 4 6% 7% 37%	2000
	11th to 20th	Night	18% 8% 3 7% 4 4 4 3 4 6% 38%	1975
	21st to end	Night	16% 8% 3 7% 6% 4 4 4 5% 6% 37%	1842
May	1st to 10th	Night	18% 9% 4 8% 5% 4 4 3 5% 6% 33%	4033
	11th to 20th	Night	15% 7% 2 6% 4 3 4 3 6% 8% 42%	3958
	21st to end	Night	15% 8% 3 7% 5% 4 3 3 4 6% 41%	3942
June	1st to 10th	Night	10% 5% 3 5% 3 3 4 4 6% 9% 48%	1597
	11th to 20th	Night	7% 6% 1 7% 4 4 5% 5% 6% 9% 46%	1520
	21st to end	Night	10% 6% 2 7% 5% 5% 4 5% 6% 8% 42%	1520
July	1st to 10th	Night	10% 5% 2 6% 5% 5% 5% 4 6% 9% 44%	2530
	11th to 20th	Night	6% 4 2 6% 4 3 4 4 5% 7% 55%	2530
	21st to end	Night	5% 5% 2 6% 5% 5% 6% 5% 7% 9% 45%	2750
August	1st to 10th	Night	7% 5% 2 6% 4 5% 5% 5% 7% 9% 46%	2733
	11th to 20th	Night	8% 5% 2 5% 4 4 5% 4 6% 7% 52%	2974
	21st to end	Night	9% 4 2 5% 4 4 4 4 6% 7% 51%	3476
September	1st to 10th	Night	10% 5% 2 5% 4 4 4 3 4 6% 53%	1900
	11th to 20th	Night	8% 4 1 5% 3 3 4 4 7% 7% 54%	2052
	21st to end	Night	10% 6% 2 6% 4 4 5% 3 6% 8% 45%	2090
October	1st to 10th	Night	11% 5% 2 6% 3 4 3 3 5% 6% 51%	2090
	11th to 20th	Night	17% 9% 2 6% 3 3 3 3 4 6% 43%	2304
	21st to end	Night	20% 9% 2 7% 4 3 3 3 5% 6% 37%	2717
November	1st to 10th	Night	13% 8% 3 7% 4 4 4 3 6% 6% 42%	2536
	11th to 20th	Night	15% 10% 3 9% 4 5% 5% 4 6% 7% 34%	2600
	21st to end	Night	19% 10% 4 8% 5% 4 4 4 5% 6% 32%	2600
December	1st to 10th	Night	12% 10% 3 7% 4 5% 5% 4 5% 6% 39%	4511
	11th to 20th	Night	18% 13% 5% 10% 6% 5% 4 4 4 5% 25%	5199
	21st to end	Night	24% 19% 6% 11% 5% 5% 4 3 4 5% 14%	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	62% 4 11% 17% 5%	3618
	11th to 20th	Day	65% 4 8% 9% 11% 3	3620
	21st to end	Day	61% 3 12% 17% 7%	3982
February	1st to 10th	Day	62% 4 12% 15% 7% 1	1932
	11th to 20th	Day	54% 5% 10% 22% 8% 1	1958
	21st to end	Day	56% 6% 12% 18% 7% 2	1650
March	1st to 10th	Day	53% 5% 7% 23% 10% 2	4480
	11th to 20th	Day	41% 5% 10% 34% 9% 1	4700
	21st to end	Day	63% 6% 12% 14% 5% 1	5874
April	1st to 10th	Day	51% 6% 10% 20% 12%	2400
	11th to 20th	Day	48% 5% 10% 23% 12% 3	2374
	21st to end	Day	48% 6% 13% 19% 11% 2	2556
May	1st to 10th	Day	49% 6% 11% 22% 11% 1	5897
	11th to 20th	Day	42% 7% 12% 25% 12% 1	5927
	21st to end	Day	40% 5% 10% 26% 17% 1	6949
June	1st to 10th	Day	37% 7% 11% 25% 17% 3	2787
	11th to 20th	Day	35% 8% 10% 23% 20% 3	2660
	21st to end	Day	38% 9% 15% 19% 16% 3	2660
July	1st to 10th	Day	44% 5% 13% 21% 14% 3	4371
	11th to 20th	Day	32% 5% 16% 29% 17% 1	4365
	21st to end	Day	39% 5% 16% 17% 19% 3	4662
August	1st to 10th	Day	34% 5% 15% 29% 16% 1	4169
	11th to 20th	Day	34% 5% 12% 32% 16% 1	3891
	21st to end	Day	32% 5% 13% 26% 20% 4	4179
September	1st to 10th	Day	35% 7% 12% 24% 17% 4	2280
	11th to 20th	Day	32% 7% 11% 25% 21% 3	2109
	21st to end	Day	39% 6% 11% 24% 19% 2	2090
October	1st to 10th	Day	28% 4 8% 32% 26% 1	3480
	11th to 20th	Day	38% 3 11% 23% 24%	3074
	21st to end	Day	47% 3 9% 27% 12% 2	3081
November	1st to 10th	Day	40% 7% 14% 23% 14% 2	1762
	11th to 20th	Day	53% 4 11% 21% 10% 1	1800
	21st to end	Day	56% 3 11% 21% 8% 1	1800
December	1st to 10th	Day	50% 4 17% 24% 5%	2674
	11th to 20th	Day	63% 4 13% 16% 4	3005
	21st to end	Day	79% 4 7% 8% 2	3982
January	1st to 10th	Night	64% 5% 9% 16% 6%	6348
	11th to 20th	Night	68% 4 9% 9% 10% 1	6360
	21st to end	Night	60% 3 11% 16% 9% 1	6978
February	1st to 10th	Night	58% 4 11% 17% 9% 1	2466
	11th to 20th	Night	51% 5% 11% 21% 11% 1	2339
	21st to end	Night	54% 6% 9% 18% 10% 2	1980
March	1st to 10th	Night	48% 6% 9% 26% 10% 1	5373
	11th to 20th	Night	39% 4 12% 29% 15% 2	5259
	21st to end	Night	53% 5% 11% 22% 8% 1	5100
April	1st to 10th	Night	45% 6% 12% 22% 14% 1	2000
	11th to 20th	Night	47% 5% 7% 21% 16% 3	1975
	21st to end	Night	48% 6% 10% 21% 14% 3	1842
May	1st to 10th	Night	52% 5% 9% 17% 14% 3	4060
	11th to 20th	Night	40% 6% 13% 26% 13% 2	3959
	21st to end	Night	45% 5% 8% 20% 19% 3	3950
June	1st to 10th	Night	32% 7% 13% 26% 19% 3	1597
	11th to 20th	Night	34% 7% 11% 23% 21% 3	1520
	21st to end	Night	38% 8% 15% 21% 15% 3	1520
July	1st to 10th	Night	37% 5% 14% 25% 13% 5%	2490
	11th to 20th	Night	29% 4 13% 24% 28% 2	2482
	21st to end	Night	33% 6% 17% 20% 20% 5%	2662
August	1st to 10th	Night	34% 6% 15% 29% 16% 1	2724
	11th to 20th	Night	31% 5% 14% 29% 21% 1	3001
	21st to end	Night	32% 4 11% 30% 19% 3	3476
September	1st to 10th	Night	32% 6% 12% 24% 20% 6%	1900
	11th to 20th	Night	27% 6% 8% 29% 26% 4	2052
	21st to end	Night	36% 6% 9% 26% 19% 3	2090
October	1st to 10th	Night	23% 4 9% 34% 29% 1	3480
	11th to 20th	Night	39% 3 7% 23% 27% 1	3827
	21st to end	Night	40% 3 9% 27% 20% 2	4467
November	1st to 10th	Night	42% 5% 10% 25% 16% 2	2536
	11th to 20th	Night	49% 5% 12% 22% 11% 2	2600
	21st to end	Night	53% 4 11% 23% 8%	2600
December	1st to 10th	Night	45% 5% 15% 27% 8% 1	4511
	11th to 20th	Night	62% 5% 12% 14% 7% 1	5201
	21st to end	Night	74% 4 8% 10% 4	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	21% 14% 36% 23% 5% 1	300
	11th to 20th	Day	22% 20% 38% 14% 5% 1	300
	21st to end	Day	23% 20% 34% 19% 4	330
February	1st to 10th	Day	19% 22% 37% 18% 4	300
	11th to 20th	Day	22% 19% 36% 18% 3	300
	21st to end	Day	24% 19% 41% 12% 4	249
March	1st to 10th	Day	23% 21% 37% 16% 3	300
	11th to 20th	Day	21% 19% 35% 19% 6%	376
	21st to end	Day	28% 16% 31% 19% 5% 1	550
April	1st to 10th	Day	26% 13% 32% 22% 6% 1	500
	11th to 20th	Day	22% 18% 31% 16% 11% 2	492
	21st to end	Day	24% 14% 32% 20% 8% 2	500
May	1st to 10th	Day	23% 13% 30% 21% 10% 2	503
	11th to 20th	Day	21% 9% 30% 22% 15% 3	550
	21st to end	Day	14% 8% 31% 25% 15% 7%	789
June	1st to 10th	Day	13% 9% 28% 28% 19% 4	726
	11th to 20th	Day	11% 6% 32% 29% 19% 4	680
	21st to end	Day	12% 8% 31% 31% 13% 5%	680
July	1st to 10th	Day	9% 5% 21% 31% 20% 13%	671
	11th to 20th	Day	10% 5% 24% 30% 21% 10%	668
	21st to end	Day	9% 3 24% 34% 22% 8%	739
August	1st to 10th	Day	9% 3 18% 30% 26% 13%	541
	11th to 20th	Day	11% 4 21% 29% 25% 11%	479
	21st to end	Day	11% 3 15% 34% 28% 9%	539
September	1st to 10th	Day	11% 6% 20% 33% 23% 7%	490
	11th to 20th	Day	10% 4 16% 28% 27% 14%	490
	21st to end	Day	14% 10% 24% 24% 19% 9%	490
October	1st to 10th	Day	13% 8% 29% 30% 16% 5%	490
	11th to 20th	Day	18% 21% 26% 25% 10% 1	329
	21st to end	Day	29% 15% 36% 16% 4 1	330
November	1st to 10th	Day	16% 12% 38% 23% 8% 2	300
	11th to 20th	Day	22% 19% 35% 17% 6% 1	300
	21st to end	Day	27% 13% 39% 18% 3	300
December	1st to 10th	Day	16% 22% 37% 19% 6%	300
	11th to 20th	Day	19% 20% 39% 18% 4 1	300
	21st to end	Day	28% 20% 35% 14% 2	330
January	1st to 10th	Night	22% 15% 37% 22% 5%	1000
	11th to 20th	Night	22% 15% 37% 21% 4 1	1000
	21st to end	Night	22% 14% 35% 25% 4	1100
February	1st to 10th	Night	23% 14% 38% 22% 3	866
	11th to 20th	Night	21% 15% 35% 25% 4	783
	21st to end	Night	25% 15% 38% 20% 2	660
March	1st to 10th	Night	21% 13% 37% 23% 6%	800
	11th to 20th	Night	17% 12% 40% 25% 6%	800
	21st to end	Night	23% 11% 34% 26% 5%	720
April	1st to 10th	Night	18% 13% 38% 25% 6% 1	600
	11th to 20th	Night	23% 9% 35% 26% 7% 1	593
	21st to end	Night	19% 11% 32% 29% 8% 1	600
May	1st to 10th	Night	20% 7% 33% 30% 9% 1	600
	11th to 20th	Night	18% 6% 28% 34% 14% 1	591
	21st to end	Night	13% 4 23% 40% 19% 2	650
June	1st to 10th	Night	11% 4 23% 44% 18%	599
	11th to 20th	Night	11% 3 28% 40% 17% 1	570
	21st to end	Night	11% 3 25% 41% 18% 1	570
July	1st to 10th	Night	8% 2 14% 45% 25% 5%	555
	11th to 20th	Night	8% 3 19% 38% 28% 4	552
	21st to end	Night	5% 2 16% 46% 30% 1	624
August	1st to 10th	Night	7% 2 9% 49% 30% 4	567
	11th to 20th	Night	9% 1 13% 41% 31% 5%	564
	21st to end	Night	8% 2 17% 38% 32% 3	627
September	1st to 10th	Night	12% 4 17% 37% 27% 4	570
	11th to 20th	Night	9% 3 19% 37% 29% 4	722
	21st to end	Night	13% 6% 24% 32% 22% 3	760
October	1st to 10th	Night	14% 5% 25% 36% 19% 1	760
	11th to 20th	Night	22% 13% 28% 27% 9%	760
	21st to end	Night	25% 11% 31% 25% 7%	836
November	1st to 10th	Night	19% 12% 36% 22% 10% 1	780
	11th to 20th	Night	20% 18% 33% 24% 5%	800
	21st to end	Night	24% 14% 34% 23% 6%	800
December	1st to 10th	Night	25% 15% 35% 22% 3	957
	11th to 20th	Night	24% 13% 35% 24% 4	1000
	21st to end	Night	30% 14% 33% 20% 3	1100

Page generated at 2025-06-07 09:28:18. Version ac07

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