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 2026-09-14.

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% 10% 3 8% 5% 5% 5% 4 6% 7% 32%	148489
	Night	15% 11% 4 9% 5% 5% 4 4 5% 7% 33%	142577
Transparency	Day	48% 6% 11% 21% 12% 1	152147
	Night	49% 5% 11% 21% 12% 2	146978
Seeing	Day	22% 14% 27% 20% 12% 5%	17264
	Night	21% 11% 26% 27% 14% 2	27441

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% 20% 6% 15% 6% 4 4 3 4 5% 18%	5258
	11th to 20th	Day	13% 19% 8% 14% 7% 6% 5% 3 4 4 17%	5280
	21st to end	Day	19% 16% 6% 11% 9% 5% 5% 4 4 5% 16%	5780
February	1st to 10th	Day	21% 15% 5% 10% 6% 4 2 3 4 4 26%	1890
	11th to 20th	Day	17% 15% 5% 12% 5% 4 4 4 4 6% 25%	1967
	21st to end	Day	18% 13% 5% 9% 5% 4 2 3 4 6% 31%	1730
March	1st to 10th	Day	17% 15% 5% 9% 5% 4 4 3 4 5% 29%	4904
	11th to 20th	Day	12% 9% 3 7% 5% 4 5% 4 5% 6% 41%	5090
	21st to end	Day	19% 10% 3 8% 5% 5% 4 4 5% 6% 32%	5586
April	1st to 10th	Day	15% 12% 3 9% 6% 4 4 4 4 6% 33%	2310
	11th to 20th	Day	15% 10% 3 7% 4 4 5% 4 6% 6% 36%	2675
	21st to end	Day	17% 8% 3 6% 5% 5% 5% 4 6% 7% 34%	2730
May	1st to 10th	Day	18% 9% 3 9% 6% 5% 5% 4 6% 7% 27%	7616
	11th to 20th	Day	17% 9% 3 7% 5% 4 5% 4 6% 8% 33%	7626
	21st to end	Day	19% 8% 3 7% 4 4 4 4 6% 8% 33%	8391
June	1st to 10th	Day	12% 7% 2 6% 5% 6% 5% 5% 6% 9% 37%	2730
	11th to 20th	Day	11% 6% 3 8% 5% 6% 5% 5% 7% 10% 34%	2730
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 5% 8% 9% 36%	2730
July	1st to 10th	Day	9% 7% 3 7% 5% 5% 6% 4 6% 9% 40%	7680
	11th to 20th	Day	10% 7% 3 7% 4 5% 5% 5% 7% 11% 37%	7680
	21st to end	Day	10% 7% 3 8% 5% 6% 5% 5% 7% 9% 35%	8340
August	1st to 10th	Day	12% 8% 3 8% 5% 5% 5% 5% 7% 8% 33%	6014
	11th to 20th	Day	13% 8% 3 9% 5% 5% 6% 5% 8% 9% 31%	5951
	21st to end	Day	4 4 2 5% 4 5% 5% 5% 7% 11% 47%	6500
September	1st to 10th	Day	12% 7% 2 5% 3 3 4 3 5% 8% 47%	2342
	11th to 20th	Day	8% 5% 2 6% 4 4 5% 4 5% 9% 47%	2233
	21st to end	Day	20% 8% 2 6% 4 3 4 3 5% 6% 39%	2200
October	1st to 10th	Day	13% 6% 2 6% 3 4 4 3 6% 8% 45%	2099
	11th to 20th	Day	14% 7% 2 6% 4 4 5% 3 5% 7% 42%	2000
	21st to end	Day	20% 10% 2 7% 4 4 3 3 5% 6% 36%	2200
November	1st to 10th	Day	11% 8% 3 6% 4 3 4 3 6% 6% 46%	1857
	11th to 20th	Day	17% 14% 3 6% 4 3 4 3 6% 6% 34%	1890
	21st to end	Day	18% 15% 4 8% 4 4 4 3 5% 5% 29%	1890
December	1st to 10th	Day	20% 12% 5% 15% 5% 4 4 3 3 4 25%	2680
	11th to 20th	Day	23% 16% 5% 10% 5% 4 4 3 4 5% 21%	3345
	21st to end	Day	21% 20% 5% 11% 6% 5% 4 3 4 5% 16%	4565
January	1st to 10th	Night	15% 18% 7% 17% 6% 5% 4 4 4 4 16%	7635
	11th to 20th	Night	12% 18% 7% 15% 8% 6% 6% 3 4 4 17%	7680
	21st to end	Night	18% 14% 6% 9% 5% 6% 4 3 4 5% 25%	8401
February	1st to 10th	Night	19% 15% 4 8% 6% 4 4 3 5% 5% 27%	2730
	11th to 20th	Night	19% 13% 4 10% 6% 5% 4 3 4 5% 25%	2535
	21st to end	Night	18% 14% 7% 10% 5% 5% 4 3 3 5% 27%	2076
March	1st to 10th	Night	20% 13% 3 7% 4 4 4 3 4 5% 34%	5169
	11th to 20th	Night	12% 9% 3 7% 4 4 4 3 6% 8% 40%	5090
	21st to end	Night	17% 9% 3 9% 5% 4 4 3 5% 6% 36%	5588
April	1st to 10th	Night	17% 11% 3 5% 4 4 4 4 5% 6% 36%	2310
	11th to 20th	Night	15% 8% 3 5% 4 5% 5% 4 7% 8% 37%	1910
	21st to end	Night	15% 8% 2 7% 4 4 5% 4 6% 8% 37%	1890
May	1st to 10th	Night	22% 10% 3 8% 5% 4 5% 4 6% 6% 28%	5237
	11th to 20th	Night	14% 8% 2 7% 4 4 4 4 6% 9% 38%	5234
	21st to end	Night	18% 9% 3 7% 4 4 4 4 5% 8% 35%	5761
June	1st to 10th	Night	9% 7% 2 6% 4 4 4 4 4 8% 47%	1890
	11th to 20th	Night	9% 6% 2 6% 4 5% 4 4 6% 10% 43%	1890
	21st to end	Night	11% 5% 2 5% 4 4 5% 5% 6% 9% 45%	1890
July	1st to 10th	Night	9% 8% 3 7% 4 5% 5% 4 6% 8% 42%	5278
	11th to 20th	Night	10% 7% 3 8% 5% 5% 5% 4 6% 9% 38%	5277
	21st to end	Night	8% 6% 3 7% 6% 5% 5% 4 7% 9% 40%	5736
August	1st to 10th	Night	12% 9% 4 8% 6% 6% 6% 4 7% 8% 32%	4135
	11th to 20th	Night	14% 9% 4 9% 4 4 4 4 4 6% 37%	4095
	21st to end	Night	4 3 1 5% 4 5% 6% 5% 8% 10% 48%	4578
September	1st to 10th	Night	12% 4 2 5% 4 3 4 3 5% 6% 52%	2274
	11th to 20th	Night	9% 4 2 4 3 4 3 3 5% 8% 55%	2234
	21st to end	Night	17% 6% 3 5% 4 4 4 3 4 6% 45%	2200
October	1st to 10th	Night	12% 5% 2 6% 3 4 4 4 4 7% 49%	2300
	11th to 20th	Night	14% 7% 3 5% 4 4 5% 4 5% 7% 43%	2400
	21st to end	Night	20% 7% 3 7% 4 4 3 3 5% 6% 39%	2640
November	1st to 10th	Night	14% 8% 2 5% 3 3 3 3 5% 6% 48%	2659
	11th to 20th	Night	16% 11% 3 7% 5% 5% 4 4 4 6% 35%	2730
	21st to end	Night	20% 13% 4 8% 4 4 4 3 5% 6% 28%	2730
December	1st to 10th	Night	18% 13% 6% 12% 5% 4 4 4 4 6% 24%	4708
	11th to 20th	Night	18% 17% 7% 11% 5% 3 4 3 4 5% 22%	5054
	21st to end	Night	21% 18% 5% 11% 5% 5% 4 3 5% 5% 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	69% 5% 12% 11% 3	5259
	11th to 20th	Day	69% 5% 8% 9% 8% 1	5280
	21st to end	Day	70% 4 8% 11% 6%	5780
February	1st to 10th	Day	63% 3 10% 16% 8%	1890
	11th to 20th	Day	61% 5% 9% 16% 9%	1976
	21st to end	Day	55% 4 12% 19% 7% 2	1730
March	1st to 10th	Day	57% 4 8% 22% 8% 2	4904
	11th to 20th	Day	42% 5% 10% 29% 10% 2	5090
	21st to end	Day	51% 5% 9% 22% 11% 2	5586
April	1st to 10th	Day	52% 6% 10% 19% 11% 2	2310
	11th to 20th	Day	46% 6% 12% 18% 15% 3	2675
	21st to end	Day	47% 7% 9% 23% 12% 2	2730
May	1st to 10th	Day	54% 7% 10% 20% 8% 2	7651
	11th to 20th	Day	47% 6% 11% 23% 12%	7630
	21st to end	Day	47% 7% 10% 18% 13% 4	8405
June	1st to 10th	Day	42% 7% 11% 24% 15% 2	2730
	11th to 20th	Day	43% 8% 13% 21% 14% 1	2730
	21st to end	Day	41% 8% 16% 20% 14% 1	2730
July	1st to 10th	Day	39% 7% 13% 26% 14% 1	7615
	11th to 20th	Day	39% 7% 12% 31% 11%	7611
	21st to end	Day	42% 7% 11% 21% 17% 2	8156
August	1st to 10th	Day	45% 8% 13% 21% 12% 2	6001
	11th to 20th	Day	46% 8% 12% 25% 9%	5990
	21st to end	Day	28% 8% 17% 32% 14% 2	6500
September	1st to 10th	Day	35% 6% 11% 23% 21% 3	2342
	11th to 20th	Day	32% 6% 13% 27% 20% 2	2233
	21st to end	Day	45% 5% 10% 21% 18% 1	2200
October	1st to 10th	Day	26% 5% 10% 33% 26% 1	3411
	11th to 20th	Day	35% 5% 13% 25% 19% 3	3240
	21st to end	Day	37% 4 13% 26% 18% 2	3538
November	1st to 10th	Day	38% 4 10% 29% 16% 3	1857
	11th to 20th	Day	51% 5% 9% 21% 12% 3	1890
	21st to end	Day	56% 5% 10% 18% 10% 1	1890
December	1st to 10th	Day	64% 4 13% 16% 4	2680
	11th to 20th	Day	66% 4 10% 15% 5%	3342
	21st to end	Day	72% 4 9% 11% 4	4565
January	1st to 10th	Night	71% 5% 10% 11% 3	7636
	11th to 20th	Night	70% 4 8% 11% 6% 1	7680
	21st to end	Night	61% 3 12% 17% 6% 1	8401
February	1st to 10th	Night	59% 5% 10% 18% 8% 1	2730
	11th to 20th	Night	61% 5% 9% 17% 8% 1	2537
	21st to end	Night	60% 4 10% 15% 9% 2	2076
March	1st to 10th	Night	52% 4 7% 26% 10% 2	5169
	11th to 20th	Night	41% 5% 12% 31% 11% 1	5090
	21st to end	Night	49% 5% 8% 23% 14% 2	5588
April	1st to 10th	Night	47% 5% 11% 21% 14% 2	2310
	11th to 20th	Night	43% 6% 12% 19% 17% 3	1910
	21st to end	Night	44% 7% 11% 22% 15% 1	1890
May	1st to 10th	Night	54% 7% 11% 17% 8% 3	5264
	11th to 20th	Night	43% 7% 10% 25% 14% 1	5235
	21st to end	Night	47% 6% 11% 20% 12% 4	5771
June	1st to 10th	Night	36% 7% 12% 23% 20% 3	1890
	11th to 20th	Night	35% 7% 16% 23% 17% 2	1890
	21st to end	Night	35% 9% 13% 24% 16% 2	1890
July	1st to 10th	Night	39% 7% 11% 23% 17% 3	5235
	11th to 20th	Night	40% 7% 13% 27% 11% 1	5226
	21st to end	Night	37% 7% 12% 20% 20% 3	5606
August	1st to 10th	Night	47% 8% 13% 20% 12% 1	4124
	11th to 20th	Night	47% 7% 11% 20% 15% 1	4122
	21st to end	Night	26% 8% 17% 32% 16% 2	4578
September	1st to 10th	Night	32% 6% 11% 22% 23% 6%	2274
	11th to 20th	Night	28% 5% 11% 28% 24% 3	2234
	21st to end	Night	42% 4 10% 20% 22% 2	2200
October	1st to 10th	Night	29% 4 7% 29% 28% 2	3755
	11th to 20th	Night	31% 5% 12% 26% 22% 5%	3899
	21st to end	Night	33% 3 8% 28% 24% 3	4252
November	1st to 10th	Night	37% 4 12% 25% 18% 3	2659
	11th to 20th	Night	49% 5% 9% 21% 14% 2	2730
	21st to end	Night	56% 5% 11% 20% 8% 1	2730
December	1st to 10th	Night	61% 5% 12% 17% 5%	4708
	11th to 20th	Night	63% 5% 13% 15% 4	5056
	21st to end	Night	68% 5% 10% 13% 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	33% 21% 33% 9% 4	330
	11th to 20th	Day	35% 27% 33% 5% 1	330
	21st to end	Day	35% 25% 29% 9% 1	363
February	1st to 10th	Day	35% 21% 32% 9% 2	330
	11th to 20th	Day	40% 24% 27% 7% 1	330
	21st to end	Day	31% 26% 38% 3 1	273
March	1st to 10th	Day	29% 23% 31% 13% 4	472
	11th to 20th	Day	31% 20% 29% 14% 6% 1	540
	21st to end	Day	32% 20% 30% 15% 3	594
April	1st to 10th	Day	28% 20% 30% 14% 6% 2	540
	11th to 20th	Day	28% 17% 29% 16% 7% 3	532
	21st to end	Day	24% 19% 33% 16% 6% 2	540
May	1st to 10th	Day	28% 20% 27% 15% 6% 3	543
	11th to 20th	Day	23% 11% 32% 21% 11% 3	567
	21st to end	Day	17% 11% 27% 24% 16% 5%	617
June	1st to 10th	Day	15% 10% 31% 26% 13% 5%	570
	11th to 20th	Day	17% 11% 25% 28% 14% 5%	570
	21st to end	Day	14% 8% 27% 29% 14% 7%	570
July	1st to 10th	Day	13% 5% 18% 27% 22% 15%	565
	11th to 20th	Day	12% 6% 22% 28% 23% 10%	564
	21st to end	Day	14% 6% 23% 26% 22% 10%	620
August	1st to 10th	Day	11% 5% 22% 30% 21% 11%	566
	11th to 20th	Day	13% 5% 21% 31% 19% 9%	559
	21st to end	Day	8% 6% 20% 28% 27% 12%	627
September	1st to 10th	Day	15% 6% 20% 27% 22% 10%	570
	11th to 20th	Day	10% 4 15% 25% 31% 14%	542
	21st to end	Day	25% 10% 19% 24% 16% 5%	530
October	1st to 10th	Day	13% 10% 25% 26% 20% 5%	530
	11th to 20th	Day	17% 14% 32% 22% 12% 3	530
	21st to end	Day	26% 15% 32% 18% 8% 1	583
November	1st to 10th	Day	19% 19% 36% 16% 8% 2	335
	11th to 20th	Day	32% 16% 30% 15% 6% 1	330
	21st to end	Day	32% 21% 32% 14% 3	330
December	1st to 10th	Day	31% 21% 31% 12% 3 1	220
	11th to 20th	Day	30% 27% 30% 9% 3	289
	21st to end	Day	38% 18% 31% 10% 3	363
January	1st to 10th	Night	28% 21% 29% 18% 4	840
	11th to 20th	Night	30% 21% 31% 16% 3	840
	21st to end	Night	30% 21% 29% 18% 2	924
February	1st to 10th	Night	30% 15% 30% 23% 2	840
	11th to 20th	Night	29% 19% 32% 18% 1	823
	21st to end	Night	29% 16% 34% 18% 3	692
March	1st to 10th	Night	25% 18% 30% 23% 3	840
	11th to 20th	Night	26% 18% 26% 22% 6% 1	840
	21st to end	Night	26% 15% 32% 21% 5%	924
April	1st to 10th	Night	25% 15% 33% 21% 6%	840
	11th to 20th	Night	20% 14% 34% 22% 9% 1	666
	21st to end	Night	19% 12% 35% 28% 6%	630
May	1st to 10th	Night	22% 11% 25% 30% 10% 1	630
	11th to 20th	Night	19% 6% 30% 31% 13% 2	621
	21st to end	Night	12% 6% 23% 35% 22% 2	683
June	1st to 10th	Night	12% 4 26% 36% 21% 1	630
	11th to 20th	Night	13% 5% 21% 39% 21% 2	630
	21st to end	Night	13% 3 21% 37% 23% 2	630
July	1st to 10th	Night	10% 3 16% 35% 31% 6%	615
	11th to 20th	Night	8% 3 17% 34% 32% 5%	612
	21st to end	Night	8% 3 16% 38% 32% 3	690
August	1st to 10th	Night	8% 3 16% 37% 34% 4	627
	11th to 20th	Night	9% 4 14% 36% 32% 4	624
	21st to end	Night	9% 2 17% 32% 34% 6%	713
September	1st to 10th	Night	14% 3 15% 36% 26% 5%	840
	11th to 20th	Night	10% 3 14% 34% 34% 5%	813
	21st to end	Night	19% 6% 23% 29% 20% 3	800
October	1st to 10th	Night	16% 6% 21% 30% 24% 3	800
	11th to 20th	Night	19% 11% 29% 27% 13% 1	800
	21st to end	Night	24% 11% 28% 28% 9%	880
November	1st to 10th	Night	19% 10% 27% 28% 15%	820
	11th to 20th	Night	25% 16% 27% 25% 7%	840
	21st to end	Night	27% 15% 27% 25% 6%	840
December	1st to 10th	Night	32% 16% 28% 19% 4	840
	11th to 20th	Night	27% 17% 30% 22% 4	840
	21st to end	Night	31% 16% 28% 23% 2	924

Page generated at 2026-09-11 04:11:54. Version ac07

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