Zanesville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Zanesville clear sky chart from 2005-11-06 to 2025-04-26.

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% 11% 3 8% 5% 5% 5% 4 5% 7% 32%	113772
	Night	15% 11% 4 9% 5% 4 4 3 5% 6% 33%	114836
Transparency	Day	49% 6% 11% 21% 12% 1	117474
	Night	49% 5% 11% 21% 12% 2	119260
Seeing	Day	22% 14% 27% 20% 12% 5%	15377
	Night	21% 11% 26% 26% 14% 2	25685

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% 21% 6% 17% 6% 3 3 2 4 4 16%	4056
	11th to 20th	Day	14% 22% 8% 12% 6% 7% 5% 3 3 4 16%	4060
	21st to end	Day	21% 18% 6% 10% 8% 5% 5% 3 4 5% 15%	4466
February	1st to 10th	Day	22% 15% 5% 10% 6% 4 2 3 4 3 26%	1800
	11th to 20th	Day	17% 15% 5% 12% 5% 4 4 4 4 6% 25%	1871
	21st to end	Day	19% 13% 5% 9% 5% 4 2 3 4 6% 31%	1650
March	1st to 10th	Day	17% 15% 5% 9% 5% 4 4 3 4 5% 29%	4797
	11th to 20th	Day	11% 8% 3 7% 5% 4 5% 4 5% 6% 41%	4980
	21st to end	Day	19% 10% 3 8% 5% 5% 4 4 5% 6% 32%	5465
April	1st to 10th	Day	15% 13% 3 9% 6% 4 4 4 4 6% 32%	2200
	11th to 20th	Day	15% 10% 3 7% 4 4 5% 4 5% 6% 36%	2546
	21st to end	Day	18% 8% 3 7% 5% 5% 5% 4 6% 7% 33%	2535
May	1st to 10th	Day	20% 10% 3 8% 6% 5% 4 4 5% 7% 27%	4082
	11th to 20th	Day	20% 9% 3 7% 5% 4 4 3 5% 7% 34%	4081
	21st to end	Day	11% 7% 3 7% 5% 5% 5% 5% 7% 11% 35%	4476
June	1st to 10th	Day	12% 7% 2 6% 5% 6% 5% 5% 6% 9% 37%	2470
	11th to 20th	Day	11% 6% 3 7% 5% 6% 5% 5% 7% 10% 35%	2470
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 5% 8% 9% 36%	2470
July	1st to 10th	Day	9% 7% 3 7% 5% 5% 6% 5% 6% 9% 38%	4120
	11th to 20th	Day	9% 6% 2 6% 4 4 5% 4 7% 11% 43%	4120
	21st to end	Day	12% 7% 3 7% 5% 7% 5% 5% 7% 8% 35%	4466
August	1st to 10th	Day	9% 7% 2 8% 5% 5% 5% 5% 8% 10% 36%	4104
	11th to 20th	Day	8% 7% 2 7% 5% 5% 6% 5% 9% 9% 36%	4044
	21st to end	Day	5% 4 2 5% 5% 5% 6% 5% 7% 10% 45%	4468
September	1st to 10th	Day	13% 7% 2 5% 3 3 4 3 6% 8% 47%	2119
	11th to 20th	Day	8% 5% 2 6% 4 4 5% 4 6% 9% 47%	2090
	21st to end	Day	20% 8% 2 6% 3 3 4 3 5% 6% 40%	2090
October	1st to 10th	Day	13% 6% 2 6% 4 4 4 3 6% 8% 43%	1994
	11th to 20th	Day	15% 7% 2 7% 4 4 5% 3 5% 7% 41%	1900
	21st to end	Day	20% 10% 2 6% 4 4 3 3 5% 6% 36%	2090
November	1st to 10th	Day	11% 8% 3 6% 4 3 3 3 6% 6% 47%	1767
	11th to 20th	Day	17% 14% 3 6% 5% 3 4 3 5% 6% 34%	1800
	21st to end	Day	18% 15% 4 8% 4 4 4 3 5% 5% 29%	1800
December	1st to 10th	Day	21% 12% 5% 15% 5% 3 4 3 3 4 25%	2600
	11th to 20th	Day	24% 17% 5% 10% 4 4 4 3 4 5% 21%	3259
	21st to end	Day	21% 20% 5% 11% 6% 5% 4 3 4 5% 16%	4466
January	1st to 10th	Night	15% 18% 7% 19% 6% 5% 3 3 3 3 16%	5889
	11th to 20th	Night	14% 19% 6% 14% 8% 7% 6% 3 4 4 15%	5900
	21st to end	Night	21% 15% 6% 10% 5% 4 3 2 4 4 25%	6490
February	1st to 10th	Night	20% 15% 4 8% 6% 4 4 3 5% 5% 27%	2600
	11th to 20th	Night	19% 13% 4 10% 6% 5% 4 3 4 5% 25%	2411
	21st to end	Night	19% 14% 7% 9% 5% 5% 4 3 3 5% 27%	1980
March	1st to 10th	Night	19% 13% 3 7% 4 4 4 3 4 5% 34%	5056
	11th to 20th	Night	12% 9% 3 7% 4 4 4 3 6% 8% 40%	4980
	21st to end	Night	17% 9% 3 9% 5% 4 4 3 5% 6% 36%	5467
April	1st to 10th	Night	17% 11% 3 6% 4 4 4 4 5% 6% 36%	2200
	11th to 20th	Night	15% 8% 3 6% 4 5% 5% 4 6% 7% 37%	1818
	21st to end	Night	15% 8% 2 7% 4 4 5% 4 6% 8% 36%	1761
May	1st to 10th	Night	26% 12% 3 7% 5% 4 4 3 5% 6% 26%	2813
	11th to 20th	Night	18% 8% 2 7% 4 4 3 3 4 7% 40%	2812
	21st to end	Night	10% 7% 2 6% 4 4 4 4 6% 10% 43%	3079
June	1st to 10th	Night	9% 7% 2 6% 5% 4 4 4 4 9% 46%	1710
	11th to 20th	Night	8% 6% 2 6% 4 5% 4 4 6% 11% 43%	1710
	21st to end	Night	11% 5% 1 5% 4 4 5% 5% 6% 9% 45%	1710
July	1st to 10th	Night	10% 8% 3 7% 4 4 4 3 6% 8% 44%	2840
	11th to 20th	Night	8% 5% 2 7% 5% 4 5% 5% 7% 8% 45%	2840
	21st to end	Night	7% 7% 3 7% 7% 5% 5% 5% 7% 9% 38%	3087
August	1st to 10th	Night	7% 7% 3 7% 6% 5% 6% 4 8% 9% 37%	2825
	11th to 20th	Night	9% 8% 3 9% 4 4 4 4 5% 7% 43%	2785
	21st to end	Night	5% 4 2 5% 4 5% 6% 5% 8% 10% 47%	3155
September	1st to 10th	Night	13% 4 1 5% 3 4 4 3 5% 6% 53%	2057
	11th to 20th	Night	9% 4 2 4 3 4 4 3 5% 8% 56%	2090
	21st to end	Night	17% 7% 3 5% 4 4 4 3 4 6% 45%	2090
October	1st to 10th	Night	12% 5% 2 6% 3 4 4 4 5% 7% 48%	2185
	11th to 20th	Night	14% 8% 3 5% 4 4 5% 4 5% 7% 41%	2280
	21st to end	Night	21% 7% 3 6% 4 4 3 3 4 6% 38%	2508
November	1st to 10th	Night	14% 8% 2 6% 3 3 3 3 4 6% 48%	2529
	11th to 20th	Night	16% 11% 3 7% 5% 5% 4 4 5% 6% 35%	2600
	21st to end	Night	20% 12% 4 8% 5% 4 4 3 5% 6% 29%	2600
December	1st to 10th	Night	18% 13% 6% 12% 5% 4 4 4 4 6% 24%	4568
	11th to 20th	Night	18% 17% 7% 11% 5% 3 4 3 4 5% 22%	4921
	21st to end	Night	21% 18% 5% 10% 5% 5% 4 3 5% 5% 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	71% 5% 9% 11% 4	4057
	11th to 20th	Day	71% 5% 8% 10% 6% 1	4060
	21st to end	Day	72% 4 8% 9% 6%	4466
February	1st to 10th	Day	64% 3 10% 15% 8%	1800
	11th to 20th	Day	61% 5% 8% 16% 9%	1880
	21st to end	Day	56% 4 12% 18% 8% 2	1650
March	1st to 10th	Day	57% 4 8% 22% 8% 2	4797
	11th to 20th	Day	42% 5% 10% 30% 11% 2	4980
	21st to end	Day	51% 5% 9% 22% 11% 2	5465
April	1st to 10th	Day	53% 5% 10% 18% 11% 2	2200
	11th to 20th	Day	47% 6% 11% 18% 15% 3	2546
	21st to end	Day	48% 7% 9% 22% 12% 2	2535
May	1st to 10th	Day	55% 6% 10% 21% 7% 1	4120
	11th to 20th	Day	50% 6% 11% 19% 13% 1	4085
	21st to end	Day	40% 10% 14% 20% 12% 4	4489
June	1st to 10th	Day	42% 8% 11% 24% 14% 1	2470
	11th to 20th	Day	42% 8% 13% 21% 14% 1	2470
	21st to end	Day	41% 9% 15% 20% 14% 1	2470
July	1st to 10th	Day	40% 7% 13% 22% 16% 2	4055
	11th to 20th	Day	33% 7% 12% 31% 16% 1	4051
	21st to end	Day	44% 7% 11% 18% 17% 3	4324
August	1st to 10th	Day	40% 8% 15% 26% 10%	4091
	11th to 20th	Day	37% 9% 11% 30% 13%	4083
	21st to end	Day	30% 8% 15% 30% 13% 3	4468
September	1st to 10th	Day	36% 6% 11% 23% 21% 3	2119
	11th to 20th	Day	32% 6% 13% 26% 20% 3	2090
	21st to end	Day	45% 5% 10% 22% 17% 1	2090
October	1st to 10th	Day	26% 5% 10% 32% 25% 1	3306
	11th to 20th	Day	35% 5% 13% 24% 19% 4	3140
	21st to end	Day	36% 4 13% 27% 19% 2	3428
November	1st to 10th	Day	38% 4 10% 29% 16% 3	1767
	11th to 20th	Day	51% 5% 9% 20% 12% 3	1800
	21st to end	Day	56% 5% 10% 18% 10% 1	1800
December	1st to 10th	Day	63% 4 13% 16% 4	2600
	11th to 20th	Day	66% 4 10% 15% 5%	3256
	21st to end	Day	72% 4 9% 11% 4	4466
January	1st to 10th	Night	72% 5% 8% 12% 3	5889
	11th to 20th	Night	72% 4 9% 9% 5%	5900
	21st to end	Night	64% 2 11% 15% 6% 2	6490
February	1st to 10th	Night	60% 5% 10% 18% 8% 1	2600
	11th to 20th	Night	61% 5% 9% 17% 9% 1	2413
	21st to end	Night	60% 4 10% 15% 9% 2	1980
March	1st to 10th	Night	51% 4 7% 26% 10% 2	5056
	11th to 20th	Night	40% 5% 12% 31% 11% 2	4980
	21st to end	Night	49% 5% 8% 23% 14% 2	5467
April	1st to 10th	Night	48% 5% 11% 21% 14% 2	2200
	11th to 20th	Night	43% 5% 11% 19% 17% 3	1818
	21st to end	Night	43% 7% 12% 21% 15% 2	1761
May	1st to 10th	Night	57% 6% 9% 18% 8% 2	2840
	11th to 20th	Night	46% 7% 9% 26% 12% 2	2813
	21st to end	Night	34% 8% 15% 26% 13% 4	3087
June	1st to 10th	Night	36% 7% 12% 24% 18% 2	1710
	11th to 20th	Night	33% 7% 16% 24% 17% 3	1710
	21st to end	Night	34% 9% 14% 25% 16% 3	1710
July	1st to 10th	Night	37% 6% 11% 23% 18% 5%	2795
	11th to 20th	Night	34% 8% 13% 29% 15% 2	2786
	21st to end	Night	39% 8% 13% 20% 16% 3	2988
August	1st to 10th	Night	40% 9% 15% 25% 12% 1	2814
	11th to 20th	Night	39% 7% 9% 23% 21% 1	2812
	21st to end	Night	28% 8% 15% 29% 17% 3	3155
September	1st to 10th	Night	33% 6% 11% 22% 22% 7%	2057
	11th to 20th	Night	28% 5% 12% 27% 25% 3	2090
	21st to end	Night	41% 4 10% 21% 22% 2	2090
October	1st to 10th	Night	30% 4 7% 29% 28% 2	3640
	11th to 20th	Night	31% 5% 12% 26% 21% 5%	3779
	21st to end	Night	33% 3 8% 27% 25% 3	4120
November	1st to 10th	Night	38% 4 12% 25% 18% 4	2529
	11th to 20th	Night	49% 5% 9% 20% 15% 2	2600
	21st to end	Night	55% 5% 11% 20% 8% 1	2600
December	1st to 10th	Night	61% 5% 12% 18% 5%	4568
	11th to 20th	Night	63% 5% 13% 15% 4	4923
	21st to end	Night	68% 5% 10% 13% 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	33% 21% 33% 8% 4	300
	11th to 20th	Day	33% 26% 34% 6% 1	300
	21st to end	Day	34% 26% 29% 9% 1	330
February	1st to 10th	Day	37% 22% 31% 8% 2	300
	11th to 20th	Day	40% 25% 27% 6% 1	300
	21st to end	Day	32% 27% 37% 3 1	249
March	1st to 10th	Day	28% 23% 31% 14% 5%	435
	11th to 20th	Day	30% 20% 29% 14% 6% 1	500
	21st to end	Day	33% 19% 30% 15% 3	550
April	1st to 10th	Day	28% 19% 29% 14% 7% 2	500
	11th to 20th	Day	28% 17% 28% 16% 7% 3	492
	21st to end	Day	24% 19% 34% 15% 6% 2	480
May	1st to 10th	Day	29% 17% 27% 16% 7% 3	463
	11th to 20th	Day	24% 10% 30% 21% 11% 4	487
	21st to end	Day	13% 10% 28% 26% 18% 5%	529
June	1st to 10th	Day	15% 9% 32% 26% 12% 5%	490
	11th to 20th	Day	17% 10% 24% 29% 15% 6%	490
	21st to end	Day	14% 8% 30% 28% 14% 7%	490
July	1st to 10th	Day	14% 5% 19% 26% 20% 15%	485
	11th to 20th	Day	12% 5% 23% 29% 22% 9%	484
	21st to end	Day	15% 5% 22% 27% 21% 10%	532
August	1st to 10th	Day	12% 4 21% 30% 20% 12%	486
	11th to 20th	Day	13% 5% 22% 31% 19% 9%	479
	21st to end	Day	9% 5% 20% 27% 27% 13%	539
September	1st to 10th	Day	15% 5% 21% 26% 23% 9%	490
	11th to 20th	Day	10% 4 16% 27% 30% 12%	490
	21st to end	Day	26% 11% 19% 23% 16% 5%	490
October	1st to 10th	Day	13% 11% 27% 26% 19% 5%	490
	11th to 20th	Day	18% 15% 31% 22% 12% 3	490
	21st to end	Day	27% 14% 31% 18% 8% 1	539
November	1st to 10th	Day	18% 20% 35% 16% 9% 3	305
	11th to 20th	Day	30% 16% 30% 15% 7% 1	300
	21st to end	Day	30% 22% 32% 14% 3	300
December	1st to 10th	Day	33% 21% 30% 13% 3 2	200
	11th to 20th	Day	31% 27% 29% 9% 4	263
	21st to end	Day	37% 19% 31% 11% 3	330
January	1st to 10th	Night	28% 22% 30% 17% 4	800
	11th to 20th	Night	31% 20% 31% 17% 3	800
	21st to end	Night	30% 20% 30% 18% 2	880
February	1st to 10th	Night	31% 15% 30% 22% 2	800
	11th to 20th	Night	30% 20% 32% 17% 1	783
	21st to end	Night	30% 16% 33% 18% 3	660
March	1st to 10th	Night	24% 18% 31% 23% 3	800
	11th to 20th	Night	25% 18% 27% 23% 6% 1	800
	21st to end	Night	26% 15% 31% 21% 6%	880
April	1st to 10th	Night	26% 15% 33% 21% 6%	800
	11th to 20th	Night	20% 15% 33% 22% 10% 1	634
	21st to end	Night	19% 12% 35% 28% 6%	587
May	1st to 10th	Night	22% 11% 26% 28% 11% 1	570
	11th to 20th	Night	19% 6% 30% 29% 13% 2	561
	21st to end	Night	11% 5% 22% 35% 24% 2	617
June	1st to 10th	Night	11% 4 26% 36% 21% 1	570
	11th to 20th	Night	12% 5% 20% 39% 22% 2	570
	21st to end	Night	13% 3 22% 37% 22% 2	570
July	1st to 10th	Night	10% 3 17% 35% 29% 6%	555
	11th to 20th	Night	8% 3 19% 34% 33% 4	552
	21st to end	Night	8% 4 16% 37% 33% 3	624
August	1st to 10th	Night	7% 2 15% 36% 35% 4	567
	11th to 20th	Night	10% 4 13% 37% 32% 4	564
	21st to end	Night	9% 2 18% 30% 34% 7%	645
September	1st to 10th	Night	15% 3 16% 34% 26% 6%	760
	11th to 20th	Night	10% 3 14% 34% 33% 5%	760
	21st to end	Night	19% 6% 23% 28% 20% 3	760
October	1st to 10th	Night	16% 6% 22% 31% 23% 3	760
	11th to 20th	Night	19% 11% 29% 26% 14% 1	760
	21st to end	Night	25% 11% 27% 28% 9%	836
November	1st to 10th	Night	20% 11% 26% 28% 16%	780
	11th to 20th	Night	25% 15% 27% 25% 8% 1	800
	21st to end	Night	27% 15% 27% 25% 6% 1	800
December	1st to 10th	Night	33% 16% 28% 18% 5%	800
	11th to 20th	Night	27% 18% 29% 22% 4	800
	21st to end	Night	31% 15% 29% 23% 2	880

Page generated at 2025-04-23 09:25:03. Version ac07

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