Wooster
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wooster clear sky chart from 2005-11-06 to 2026-05-17.

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% 4 9% 5% 5% 5% 4 5% 7% 31%	131538
	Night	15% 12% 4 9% 5% 5% 4 3 5% 6% 31%	131253
Transparency	Day	52% 5% 11% 20% 11% 1	135183
	Night	52% 5% 11% 20% 12% 1	135678
Seeing	Day	20% 12% 27% 21% 14% 6%	16594
	Night	20% 9% 27% 30% 13% 2	26751

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% 20% 6% 19% 6% 4 4 3 4 5% 15%	5258
	11th to 20th	Day	11% 19% 7% 17% 8% 5% 4 3 4 4 17%	5280
	21st to end	Day	19% 17% 7% 13% 8% 7% 5% 3 4 4 14%	5780
February	1st to 10th	Day	17% 16% 6% 11% 7% 4 4 3 4 5% 23%	1890
	11th to 20th	Day	16% 13% 5% 14% 7% 5% 5% 3 4 5% 23%	1940
	21st to end	Day	16% 15% 5% 11% 5% 4 4 4 5% 6% 27%	1730
March	1st to 10th	Day	17% 13% 5% 11% 5% 4 4 3 4 5% 28%	4898
	11th to 20th	Day	11% 10% 4 10% 5% 5% 4 3 5% 6% 37%	5090
	21st to end	Day	19% 11% 5% 10% 5% 4 4 4 5% 6% 28%	5586
April	1st to 10th	Day	14% 13% 4 9% 5% 5% 4 5% 5% 7% 30%	2326
	11th to 20th	Day	16% 10% 3 8% 5% 5% 4 3 4 6% 34%	2688
	21st to end	Day	18% 10% 3 8% 5% 4 4 4 5% 6% 33%	2730
May	1st to 10th	Day	21% 9% 3 8% 6% 5% 5% 4 5% 6% 28%	5992
	11th to 20th	Day	17% 9% 3 8% 5% 4 5% 4 6% 8% 32%	5939
	21st to end	Day	18% 6% 2 6% 4 4 6% 5% 6% 8% 34%	6433
June	1st to 10th	Day	11% 7% 3 7% 5% 5% 5% 4 6% 9% 37%	2665
	11th to 20th	Day	13% 7% 3 8% 5% 4 5% 4 8% 8% 35%	2800
	21st to end	Day	10% 6% 2 6% 5% 5% 5% 5% 8% 9% 39%	2605
July	1st to 10th	Day	8% 6% 3 8% 5% 5% 4 4 6% 10% 40%	5900
	11th to 20th	Day	9% 7% 2 6% 5% 5% 6% 5% 7% 10% 36%	5900
	21st to end	Day	11% 6% 3 7% 5% 5% 5% 4 7% 10% 37%	6424
August	1st to 10th	Day	11% 8% 3 8% 5% 6% 5% 5% 7% 9% 35%	4234
	11th to 20th	Day	9% 7% 2 6% 5% 5% 6% 5% 8% 10% 36%	4174
	21st to end	Day	7% 5% 2 6% 5% 6% 6% 5% 7% 9% 40%	4618
September	1st to 10th	Day	13% 5% 2 5% 5% 4 4 3 5% 7% 46%	2254
	11th to 20th	Day	9% 6% 2 5% 5% 4 5% 4 7% 9% 44%	2200
	21st to end	Day	18% 8% 3 6% 4 4 4 3 5% 7% 38%	2200
October	1st to 10th	Day	13% 7% 3 6% 4 5% 4 3 6% 7% 42%	2089
	11th to 20th	Day	16% 9% 3 7% 4 4 4 4 5% 6% 39%	2000
	21st to end	Day	20% 11% 3 7% 5% 5% 4 3 4 6% 33%	2183
November	1st to 10th	Day	11% 9% 3 8% 5% 5% 3 3 5% 6% 41%	1852
	11th to 20th	Day	16% 13% 4 8% 6% 4 4 3 4 6% 31%	1890
	21st to end	Day	16% 16% 5% 10% 6% 6% 4 3 5% 6% 24%	1745
December	1st to 10th	Day	18% 14% 5% 15% 5% 4 4 3 4 4 23%	2680
	11th to 20th	Day	22% 17% 6% 12% 4 3 3 2 4 6% 20%	3070
	21st to end	Day	22% 22% 6% 13% 6% 5% 4 3 3 4 12%	4495
January	1st to 10th	Night	15% 18% 6% 20% 8% 5% 4 3 3 4 13%	7635
	11th to 20th	Night	10% 18% 10% 17% 8% 6% 5% 3 4 4 14%	7680
	21st to end	Night	17% 16% 6% 12% 6% 6% 4 3 4 6% 21%	8401
February	1st to 10th	Night	19% 14% 5% 11% 6% 5% 4 3 5% 5% 23%	2730
	11th to 20th	Night	16% 15% 6% 11% 7% 5% 4 3 6% 6% 22%	2564
	21st to end	Night	17% 14% 5% 12% 7% 4 4 3 4 5% 24%	2076
March	1st to 10th	Night	21% 13% 4 9% 4 3 3 2 4 5% 33%	5174
	11th to 20th	Night	12% 8% 3 6% 5% 4 5% 4 6% 8% 39%	5090
	21st to end	Night	16% 11% 4 8% 5% 4 4 3 4 6% 35%	5588
April	1st to 10th	Night	17% 13% 3 7% 5% 5% 4 3 5% 6% 33%	2294
	11th to 20th	Night	15% 9% 4 8% 5% 4 4 4 6% 7% 35%	1898
	21st to end	Night	15% 9% 3 7% 5% 5% 5% 4 5% 7% 37%	1890
May	1st to 10th	Night	23% 11% 3 8% 5% 4 4 4 5% 6% 26%	4123
	11th to 20th	Night	16% 9% 3 6% 4 3 4 3 5% 8% 38%	4086
	21st to end	Night	14% 8% 2 6% 4 4 5% 4 6% 9% 39%	4421
June	1st to 10th	Night	9% 7% 2 7% 5% 5% 4 3 6% 7% 45%	1725
	11th to 20th	Night	9% 6% 2 6% 5% 4 5% 5% 7% 10% 40%	1600
	21st to end	Night	9% 6% 2 6% 5% 4 5% 4 7% 9% 43%	1781
July	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 7% 9% 44%	4058
	11th to 20th	Night	9% 5% 2 7% 4 5% 5% 5% 7% 9% 41%	4057
	21st to end	Night	7% 6% 3 7% 5% 4 5% 4 6% 8% 45%	4427
August	1st to 10th	Night	9% 8% 3 8% 5% 4 5% 4 7% 9% 38%	2915
	11th to 20th	Night	10% 8% 2 8% 4 4 4 3 5% 7% 44%	2875
	21st to end	Night	6% 5% 2 6% 4 6% 5% 5% 6% 9% 47%	3246
September	1st to 10th	Night	11% 5% 1 6% 3 3 4 3 4 7% 52%	2142
	11th to 20th	Night	9% 4 2 4 3 3 4 4 6% 8% 55%	2200
	21st to end	Night	15% 8% 3 6% 5% 3 4 3 5% 6% 42%	2200
October	1st to 10th	Night	12% 5% 2 6% 4 4 4 4 6% 7% 47%	2310
	11th to 20th	Night	15% 9% 2 7% 5% 4 4 3 5% 7% 39%	2400
	21st to end	Night	21% 8% 3 6% 4 4 4 3 5% 7% 35%	2655
November	1st to 10th	Night	13% 8% 2 6% 4 4 5% 4 5% 7% 43%	2666
	11th to 20th	Night	16% 13% 4 7% 5% 4 3 3 6% 6% 32%	2730
	21st to end	Night	19% 14% 4 8% 5% 4 3 4 4 6% 27%	2870
December	1st to 10th	Night	17% 15% 5% 13% 6% 5% 4 4 4 6% 23%	4720
	11th to 20th	Night	19% 17% 7% 12% 5% 4 4 3 4 5% 20%	5345
	21st to end	Night	20% 21% 7% 12% 5% 5% 4 2 4 5% 15%	6681

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	73% 3 11% 10% 3	5259
	11th to 20th	Day	72% 2 8% 8% 9%	5280
	21st to end	Day	75% 3 5% 13% 4	5780
February	1st to 10th	Day	64% 4 8% 16% 7% 1	1890
	11th to 20th	Day	64% 5% 7% 17% 7% 1	1949
	21st to end	Day	58% 3 13% 16% 8% 2	1730
March	1st to 10th	Day	59% 4 7% 23% 7%	4898
	11th to 20th	Day	48% 4 10% 27% 9% 2	5090
	21st to end	Day	57% 4 8% 18% 11% 1	5586
April	1st to 10th	Day	53% 6% 13% 17% 11% 1	2326
	11th to 20th	Day	51% 5% 12% 17% 13% 2	2688
	21st to end	Day	51% 6% 10% 21% 10% 2	2730
May	1st to 10th	Day	56% 5% 9% 17% 10% 3	6027
	11th to 20th	Day	50% 6% 12% 21% 11% 1	5943
	21st to end	Day	45% 7% 11% 22% 11% 4	6447
June	1st to 10th	Day	42% 8% 11% 24% 13% 1	2665
	11th to 20th	Day	45% 7% 13% 21% 13% 1	2800
	21st to end	Day	38% 8% 14% 23% 15% 2	2605
July	1st to 10th	Day	39% 5% 12% 29% 14% 1	5835
	11th to 20th	Day	41% 6% 14% 23% 15% 1	5831
	21st to end	Day	40% 6% 13% 20% 19% 2	6240
August	1st to 10th	Day	44% 7% 14% 22% 12%	4221
	11th to 20th	Day	39% 8% 11% 30% 11% 1	4213
	21st to end	Day	37% 7% 14% 29% 11% 2	4618
September	1st to 10th	Day	37% 6% 13% 23% 19% 4	2254
	11th to 20th	Day	35% 6% 13% 27% 16% 3	2200
	21st to end	Day	47% 5% 10% 20% 17% 1	2200
October	1st to 10th	Day	31% 4 11% 31% 21% 1	3401
	11th to 20th	Day	41% 4 11% 23% 16% 4	3240
	21st to end	Day	41% 4 12% 25% 17% 1	3509
November	1st to 10th	Day	43% 5% 12% 24% 15% 2	1852
	11th to 20th	Day	55% 4 9% 20% 10% 2	1890
	21st to end	Day	62% 5% 9% 17% 6% 1	1745
December	1st to 10th	Day	65% 4 13% 14% 4	2680
	11th to 20th	Day	67% 3 10% 15% 5%	3066
	21st to end	Day	78% 3 7% 8% 4	4495
January	1st to 10th	Night	76% 4 7% 10% 3	7636
	11th to 20th	Night	75% 3 7% 9% 6%	7680
	21st to end	Night	66% 3 9% 14% 6% 1	8401
February	1st to 10th	Night	63% 4 11% 16% 6%	2730
	11th to 20th	Night	62% 5% 11% 15% 7% 1	2566
	21st to end	Night	63% 4 9% 14% 9% 2	2076
March	1st to 10th	Night	56% 3 10% 21% 10%	5174
	11th to 20th	Night	41% 6% 13% 29% 9% 2	5090
	21st to end	Night	51% 4 9% 21% 14% 1	5588
April	1st to 10th	Night	52% 6% 10% 18% 13% 2	2294
	11th to 20th	Night	47% 6% 12% 17% 15% 3	1898
	21st to end	Night	46% 5% 11% 21% 15% 2	1890
May	1st to 10th	Night	58% 6% 9% 15% 8% 4	4150
	11th to 20th	Night	44% 6% 10% 23% 15% 1	4087
	21st to end	Night	41% 6% 13% 26% 11% 2	4429
June	1st to 10th	Night	38% 6% 10% 24% 18% 3	1725
	11th to 20th	Night	36% 8% 14% 23% 17% 2	1600
	21st to end	Night	35% 8% 13% 25% 18% 2	1781
July	1st to 10th	Night	36% 5% 13% 25% 18% 4	4015
	11th to 20th	Night	37% 7% 15% 28% 13% 1	4006
	21st to end	Night	37% 5% 12% 21% 23% 2	4297
August	1st to 10th	Night	41% 6% 13% 24% 14% 1	2904
	11th to 20th	Night	39% 6% 11% 27% 16% 1	2902
	21st to end	Night	33% 6% 15% 31% 14% 2	3246
September	1st to 10th	Night	32% 6% 11% 28% 19% 4	2142
	11th to 20th	Night	27% 7% 12% 27% 26% 2	2200
	21st to end	Night	43% 5% 10% 21% 20% 2	2200
October	1st to 10th	Night	30% 4 8% 29% 27% 1	3778
	11th to 20th	Night	37% 4 12% 23% 19% 4	3899
	21st to end	Night	37% 3 10% 29% 19% 2	4279
November	1st to 10th	Night	40% 4 12% 24% 16% 3	2666
	11th to 20th	Night	52% 3 11% 21% 11% 2	2730
	21st to end	Night	59% 4 12% 18% 6% 1	2870
December	1st to 10th	Night	63% 4 11% 17% 4	4720
	11th to 20th	Night	66% 4 13% 14% 3	5348
	21st to end	Night	73% 3 10% 11% 3	6681

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	26% 22% 38% 10% 4 1	330
	11th to 20th	Day	28% 27% 35% 7% 2 1	330
	21st to end	Day	27% 24% 34% 13% 2	363
February	1st to 10th	Day	25% 22% 36% 15% 3	330
	11th to 20th	Day	29% 27% 33% 9% 2	330
	21st to end	Day	26% 29% 34% 10%	273
March	1st to 10th	Day	26% 18% 33% 19% 4	466
	11th to 20th	Day	27% 14% 36% 16% 6% 1	540
	21st to end	Day	30% 15% 29% 21% 4	594
April	1st to 10th	Day	23% 19% 32% 17% 7% 2	540
	11th to 20th	Day	23% 19% 27% 17% 9% 4	532
	21st to end	Day	23% 13% 31% 20% 10% 2	540
May	1st to 10th	Day	26% 17% 28% 19% 8% 3	543
	11th to 20th	Day	20% 11% 30% 21% 13% 5%	551
	21st to end	Day	15% 8% 24% 26% 20% 7%	573
June	1st to 10th	Day	14% 6% 28% 31% 15% 5%	530
	11th to 20th	Day	16% 9% 20% 30% 20% 5%	530
	21st to end	Day	12% 5% 27% 27% 21% 7%	530
July	1st to 10th	Day	12% 3 19% 26% 25% 16%	525
	11th to 20th	Day	12% 4 21% 25% 25% 12%	524
	21st to end	Day	12% 4 18% 25% 28% 12%	576
August	1st to 10th	Day	11% 3 15% 29% 26% 15%	526
	11th to 20th	Day	13% 5% 19% 28% 23% 13%	519
	21st to end	Day	9% 5% 15% 30% 24% 17%	583
September	1st to 10th	Day	12% 6% 20% 24% 23% 15%	530
	11th to 20th	Day	9% 3 14% 23% 31% 19%	530
	21st to end	Day	25% 7% 20% 22% 17% 9%	530
October	1st to 10th	Day	12% 8% 25% 26% 22% 8%	530
	11th to 20th	Day	17% 13% 33% 23% 9% 4	530
	21st to end	Day	27% 13% 33% 20% 7% 1	566
November	1st to 10th	Day	17% 16% 38% 17% 11% 2	330
	11th to 20th	Day	30% 14% 34% 14% 6% 1	330
	21st to end	Day	26% 18% 40% 14% 1	253
December	1st to 10th	Day	25% 18% 38% 14% 4 1	220
	11th to 20th	Day	27% 23% 34% 14% 3	220
	21st to end	Day	31% 22% 33% 13% 2	347
January	1st to 10th	Night	25% 16% 34% 21% 4	840
	11th to 20th	Night	28% 17% 36% 16% 4	840
	21st to end	Night	26% 17% 32% 22% 3	924
February	1st to 10th	Night	26% 13% 35% 23% 3	840
	11th to 20th	Night	26% 16% 34% 23% 2	823
	21st to end	Night	26% 13% 38% 20% 2	692
March	1st to 10th	Night	24% 13% 34% 24% 5%	840
	11th to 20th	Night	20% 15% 34% 25% 6% 1	840
	21st to end	Night	24% 11% 33% 25% 6% 1	924
April	1st to 10th	Night	22% 13% 36% 25% 4 1	840
	11th to 20th	Night	19% 12% 33% 26% 9% 1	654
	21st to end	Night	18% 8% 31% 35% 7% 1	630
May	1st to 10th	Night	22% 7% 28% 34% 9% 1	630
	11th to 20th	Night	19% 7% 24% 37% 11% 2	609
	21st to end	Night	12% 3 17% 43% 23% 3	650
June	1st to 10th	Night	10% 5% 21% 44% 20%	525
	11th to 20th	Night	13% 3 20% 47% 17% 1	400
	21st to end	Night	11% 2 21% 41% 23% 1	581
July	1st to 10th	Night	10% 2 12% 42% 28% 5%	585
	11th to 20th	Night	7% 3 15% 41% 30% 4	582
	21st to end	Night	8% 3 12% 44% 30% 3	657
August	1st to 10th	Night	8% 2 11% 45% 31% 3	597
	11th to 20th	Night	10% 3 11% 41% 30% 5%	594
	21st to end	Night	9% 2 14% 35% 35% 6%	670
September	1st to 10th	Night	12% 4 18% 34% 29% 5%	800
	11th to 20th	Night	11% 2 11% 35% 36% 5%	800
	21st to end	Night	18% 6% 22% 31% 20% 4	800
October	1st to 10th	Night	14% 6% 19% 36% 21% 3	800
	11th to 20th	Night	19% 9% 30% 28% 12% 2	800
	21st to end	Night	25% 10% 28% 29% 8%	880
November	1st to 10th	Night	18% 9% 30% 31% 11% 1	820
	11th to 20th	Night	23% 13% 31% 25% 8% 1	840
	21st to end	Night	28% 10% 34% 23% 5% 1	840
December	1st to 10th	Night	30% 13% 31% 22% 4	840
	11th to 20th	Night	26% 13% 35% 22% 4	840
	21st to end	Night	27% 15% 32% 24% 2	924

Page generated at 2026-05-14 01:58:57. Version ac07

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