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 2024-01-22.

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% 4 7% 6% 4 5% 5% 5% 7% 32%	74604
	Night	15% 10% 4 7% 6% 3 4 5% 5% 7% 34%	75303
Transparency	Day	51% 6% 11% 19% 11% 1	74325
	Night	50% 6% 11% 20% 12% 2	75101
Seeing	Day	20% 12% 27% 21% 14% 6%	13557
	Night	20% 9% 27% 30% 13% 2	23717

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	18% 16% 7% 11% 8% 4 4 4 5% 5% 19%	1706
	11th to 20th	Day	19% 18% 7% 12% 8% 3 4 4 4 5% 16%	1710
	21st to end	Day	17% 19% 8% 12% 8% 4 4 4 4 5% 15%	1791
February	1st to 10th	Day	19% 16% 7% 10% 8% 4 4 4 4 5% 21%	1620
	11th to 20th	Day	16% 13% 6% 13% 8% 4 5% 5% 4 5% 22%	1656
	21st to end	Day	17% 15% 5% 9% 7% 2 4 4 4 5% 27%	1480
March	1st to 10th	Day	19% 12% 5% 7% 7% 3 4 4 4 6% 29%	1916
	11th to 20th	Day	17% 13% 5% 9% 6% 3 4 5% 5% 5% 29%	1980
	21st to end	Day	22% 9% 5% 8% 6% 3 4 5% 4 6% 27%	2178
April	1st to 10th	Day	13% 12% 5% 7% 7% 3 4 5% 5% 7% 32%	1993
	11th to 20th	Day	18% 10% 3 8% 5% 4 4 4 4 6% 34%	2299
	21st to end	Day	19% 10% 4 7% 5% 3 4 5% 5% 6% 32%	2340
May	1st to 10th	Day	17% 9% 3 7% 8% 4 5% 5% 5% 6% 30%	2340
	11th to 20th	Day	19% 8% 3 6% 7% 3 5% 5% 6% 7% 31%	2301
	21st to end	Day	10% 5% 2 6% 6% 4 7% 6% 7% 9% 38%	2531
June	1st to 10th	Day	11% 6% 4 6% 6% 4 5% 5% 6% 9% 37%	2398
	11th to 20th	Day	13% 6% 3 6% 6% 3 5% 6% 8% 9% 35%	2520
	21st to end	Day	11% 5% 3 6% 5% 3 6% 6% 7% 10% 38%	2345
July	1st to 10th	Day	11% 6% 3 6% 6% 4 5% 6% 6% 8% 40%	2340
	11th to 20th	Day	11% 5% 3 5% 5% 4 7% 6% 6% 9% 40%	2340
	21st to end	Day	10% 5% 3 6% 6% 4 6% 6% 6% 11% 36%	2547
August	1st to 10th	Day	8% 6% 2 6% 7% 4 6% 7% 8% 9% 36%	2327
	11th to 20th	Day	10% 6% 2 5% 6% 4 7% 6% 8% 9% 35%	2303
	21st to end	Day	9% 5% 2 5% 5% 5% 6% 7% 7% 8% 39%	2547
September	1st to 10th	Day	14% 5% 2 5% 6% 3 4 5% 5% 7% 43%	2030
	11th to 20th	Day	10% 6% 2 5% 6% 3 5% 5% 7% 9% 42%	1980
	21st to end	Day	17% 8% 3 5% 5% 3 4 4 4 7% 39%	1980
October	1st to 10th	Day	14% 7% 3 6% 5% 4 5% 4 6% 7% 39%	1881
	11th to 20th	Day	17% 9% 3 6% 5% 3 4 5% 5% 6% 36%	1800
	21st to end	Day	22% 11% 3 7% 6% 3 4 4 4 5% 31%	1965
November	1st to 10th	Day	10% 9% 4 7% 6% 3 4 4 5% 6% 42%	1672
	11th to 20th	Day	16% 12% 5% 7% 6% 3 4 4 4 6% 31%	1710
	21st to end	Day	17% 14% 5% 8% 6% 4 5% 5% 4 6% 26%	1579
December	1st to 10th	Day	18% 18% 7% 11% 7% 3 4 4 4 4 21%	1520
	11th to 20th	Day	18% 15% 6% 13% 6% 2 4 3 5% 7% 19%	1910
	21st to end	Day	23% 22% 8% 11% 6% 3 4 4 3 4 11%	3069
January	1st to 10th	Night	18% 16% 6% 9% 8% 4 5% 5% 3 5% 22%	2459
	11th to 20th	Night	18% 17% 7% 12% 8% 3 5% 4 4 4 19%	2470
	21st to end	Night	17% 18% 6% 10% 9% 3 4 4 4 5% 20%	2599
February	1st to 10th	Night	21% 14% 6% 10% 7% 4 4 4 4 5% 21%	2340
	11th to 20th	Night	17% 14% 6% 8% 7% 4 5% 4 6% 6% 23%	2188
	21st to end	Night	19% 13% 6% 10% 8% 3 4 4 4 5% 24%	1776
March	1st to 10th	Night	16% 11% 5% 8% 6% 3 4 4 4 5% 33%	2044
	11th to 20th	Night	16% 9% 3 6% 6% 3 4 5% 6% 7% 35%	1980
	21st to end	Night	19% 11% 4 7% 5% 4 4 4 4 6% 32%	2178
April	1st to 10th	Night	14% 11% 5% 6% 6% 3 5% 4 5% 7% 34%	1967
	11th to 20th	Night	15% 8% 4 7% 6% 3 4 4 6% 7% 35%	1625
	21st to end	Night	16% 8% 3 6% 6% 3 5% 5% 5% 7% 37%	1620
May	1st to 10th	Night	16% 9% 4 7% 7% 4 5% 6% 5% 6% 31%	1620
	11th to 20th	Night	17% 8% 3 6% 5% 2 4 4 5% 7% 38%	1592
	21st to end	Night	8% 5% 2 5% 5% 3 6% 6% 6% 11% 42%	1744
June	1st to 10th	Night	9% 6% 2 7% 6% 4 4 4 6% 7% 45%	1553
	11th to 20th	Night	9% 6% 2 5% 5% 3 5% 6% 7% 11% 41%	1440
	21st to end	Night	9% 5% 2 4 5% 3 5% 5% 7% 9% 44%	1602
July	1st to 10th	Night	8% 5% 2 6% 6% 3 4 5% 5% 8% 48%	1620
	11th to 20th	Night	7% 4 2 5% 5% 3 5% 5% 7% 11% 46%	1620
	21st to end	Night	7% 5% 3 6% 6% 3 5% 5% 7% 8% 44%	1771
August	1st to 10th	Night	6% 5% 2 5% 5% 3 5% 6% 7% 11% 45%	1611
	11th to 20th	Night	8% 6% 3 6% 5% 4 4 5% 6% 9% 46%	1598
	21st to end	Night	8% 4 3 5% 4 3 5% 6% 5% 9% 49%	1790
September	1st to 10th	Night	12% 5% 2 5% 5% 2 4 4 5% 7% 49%	1927
	11th to 20th	Night	10% 4 2 4 3 2 3 5% 6% 8% 54%	1980
	21st to end	Night	14% 7% 3 5% 5% 3 4 4 5% 6% 44%	1980
October	1st to 10th	Night	13% 6% 2 5% 5% 3 4 5% 6% 7% 44%	2078
	11th to 20th	Night	16% 9% 2 6% 6% 3 4 4 5% 7% 37%	2160
	21st to end	Night	23% 8% 3 5% 5% 3 5% 4 5% 6% 33%	2389
November	1st to 10th	Night	14% 8% 3 5% 4 3 4 5% 6% 7% 42%	2406
	11th to 20th	Night	16% 12% 5% 7% 6% 3 4 4 6% 6% 32%	2470
	21st to end	Night	19% 13% 4 7% 6% 3 5% 4 5% 6% 28%	2596
December	1st to 10th	Night	21% 16% 6% 9% 6% 4 4 4 4 5% 22%	2660
	11th to 20th	Night	17% 14% 6% 10% 6% 3 4 4 5% 6% 24%	3285
	21st to end	Night	22% 21% 8% 9% 6% 4 4 4 3 5% 14%	4565

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	67% 4 10% 14% 5%	1707
	11th to 20th	Day	71% 4 12% 10% 3	1710
	21st to end	Day	72% 5% 7% 12% 4 1	1791
February	1st to 10th	Day	67% 5% 8% 14% 6% 1	1620
	11th to 20th	Day	65% 6% 7% 15% 7% 1	1665
	21st to end	Day	60% 3 12% 15% 8% 2	1480
March	1st to 10th	Day	56% 5% 11% 21% 7%	1916
	11th to 20th	Day	57% 6% 9% 17% 10% 2	1980
	21st to end	Day	58% 5% 8% 18% 10% 1	2178
April	1st to 10th	Day	51% 6% 13% 18% 12% 1	1993
	11th to 20th	Day	52% 5% 11% 16% 14% 2	2299
	21st to end	Day	53% 6% 10% 20% 10% 2	2340
May	1st to 10th	Day	54% 6% 11% 19% 8% 1	2340
	11th to 20th	Day	51% 7% 11% 16% 12% 2	2305
	21st to end	Day	40% 9% 14% 23% 13% 1	2531
June	1st to 10th	Day	43% 8% 11% 24% 13% 1	2398
	11th to 20th	Day	44% 7% 13% 21% 12% 1	2520
	21st to end	Day	39% 8% 13% 23% 15% 2	2345
July	1st to 10th	Day	41% 8% 12% 23% 15% 2	2275
	11th to 20th	Day	38% 8% 13% 24% 15% 2	2271
	21st to end	Day	38% 9% 14% 24% 12% 2	2405
August	1st to 10th	Day	40% 9% 13% 24% 12% 1	2314
	11th to 20th	Day	41% 10% 14% 23% 11% 1	2303
	21st to end	Day	38% 10% 12% 22% 15% 4	2547
September	1st to 10th	Day	39% 6% 13% 21% 17% 3	2030
	11th to 20th	Day	37% 7% 13% 26% 15% 2	1980
	21st to end	Day	45% 6% 10% 22% 17% 1	1980
October	1st to 10th	Day	42% 7% 10% 23% 17% 1	1881
	11th to 20th	Day	47% 5% 13% 22% 13% 1	1800
	21st to end	Day	55% 5% 12% 17% 9% 1	1965
November	1st to 10th	Day	42% 5% 11% 24% 15% 2	1672
	11th to 20th	Day	54% 5% 9% 20% 10% 2	1710
	21st to end	Day	60% 6% 9% 17% 7% 1	1579
December	1st to 10th	Day	68% 4 10% 13% 4	1520
	11th to 20th	Day	65% 4 10% 17% 4	1906
	21st to end	Day	78% 4 9% 7% 3	3069
January	1st to 10th	Night	66% 5% 9% 15% 6%	2459
	11th to 20th	Night	69% 4 10% 13% 3	2470
	21st to end	Night	66% 4 9% 15% 5% 1	2599
February	1st to 10th	Night	64% 5% 11% 14% 5%	2340
	11th to 20th	Night	60% 5% 11% 15% 8% 1	2190
	21st to end	Night	63% 5% 8% 14% 8% 2	1776
March	1st to 10th	Night	54% 5% 9% 20% 11% 1	2044
	11th to 20th	Night	47% 6% 12% 22% 9% 3	1980
	21st to end	Night	53% 5% 8% 21% 11% 2	2178
April	1st to 10th	Night	49% 6% 11% 18% 14% 2	1967
	11th to 20th	Night	47% 6% 11% 17% 16% 3	1625
	21st to end	Night	47% 5% 11% 20% 15% 2	1620
May	1st to 10th	Night	51% 7% 11% 16% 12% 2	1620
	11th to 20th	Night	45% 6% 11% 18% 16% 3	1593
	21st to end	Night	35% 8% 16% 26% 14% 1	1745
June	1st to 10th	Night	38% 7% 11% 24% 17% 3	1553
	11th to 20th	Night	35% 9% 13% 23% 18% 2	1440
	21st to end	Night	34% 8% 13% 25% 18% 2	1602
July	1st to 10th	Night	35% 7% 13% 23% 18% 4	1575
	11th to 20th	Night	30% 8% 14% 28% 17% 2	1566
	21st to end	Night	34% 8% 15% 25% 15% 3	1672
August	1st to 10th	Night	31% 8% 16% 27% 18% 1	1600
	11th to 20th	Night	33% 8% 16% 26% 15% 2	1598
	21st to end	Night	31% 7% 14% 26% 18% 3	1790
September	1st to 10th	Night	34% 7% 12% 26% 17% 5%	1927
	11th to 20th	Night	28% 7% 12% 26% 25% 2	1980
	21st to end	Night	40% 5% 10% 23% 20% 2	1980
October	1st to 10th	Night	37% 7% 12% 23% 20% 1	2078
	11th to 20th	Night	46% 6% 9% 24% 13% 1	2160
	21st to end	Night	52% 5% 10% 21% 10% 2	2389
November	1st to 10th	Night	41% 5% 13% 23% 16% 3	2406
	11th to 20th	Night	52% 3 11% 20% 12% 2	2470
	21st to end	Night	58% 4 12% 19% 6% 1	2596
December	1st to 10th	Night	65% 4 10% 14% 6%	2660
	11th to 20th	Night	60% 5% 13% 19% 3	3288
	21st to end	Night	74% 4 10% 10% 2	4565

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	27% 21% 34% 11% 5% 1	270
	11th to 20th	Day	28% 24% 36% 9% 3 1	270
	21st to end	Day	26% 22% 36% 12% 3	267
February	1st to 10th	Day	31% 20% 35% 12% 1	240
	11th to 20th	Day	30% 28% 32% 8% 1	240
	21st to end	Day	28% 30% 32% 10% 1	198
March	1st to 10th	Day	26% 19% 31% 21% 4	356
	11th to 20th	Day	26% 12% 37% 17% 7% 1	420
	21st to end	Day	32% 14% 26% 23% 5%	462
April	1st to 10th	Day	22% 16% 32% 19% 9% 2	420
	11th to 20th	Day	23% 17% 26% 19% 10% 5%	412
	21st to end	Day	25% 14% 31% 19% 10% 2	420
May	1st to 10th	Day	26% 14% 26% 21% 9% 4	423
	11th to 20th	Day	20% 10% 31% 21% 13% 5%	447
	21st to end	Day	14% 6% 23% 27% 22% 8%	485
June	1st to 10th	Day	14% 5% 28% 32% 16% 5%	450
	11th to 20th	Day	16% 10% 20% 27% 21% 5%	450
	21st to end	Day	12% 6% 27% 28% 21% 6%	450
July	1st to 10th	Day	13% 2 18% 26% 24% 17%	445
	11th to 20th	Day	13% 3 21% 27% 24% 13%	444
	21st to end	Day	12% 4 20% 25% 28% 12%	488
August	1st to 10th	Day	12% 3 14% 30% 25% 15%	446
	11th to 20th	Day	13% 5% 19% 27% 22% 13%	439
	21st to end	Day	10% 6% 15% 28% 24% 18%	495
September	1st to 10th	Day	13% 5% 21% 25% 23% 14%	450
	11th to 20th	Day	11% 4 16% 23% 30% 16%	450
	21st to end	Day	22% 8% 20% 22% 18% 10%	450
October	1st to 10th	Day	13% 8% 26% 25% 21% 7%	450
	11th to 20th	Day	19% 14% 33% 24% 8% 2	450
	21st to end	Day	29% 14% 31% 20% 6%	480
November	1st to 10th	Day	15% 17% 38% 17% 11% 2	270
	11th to 20th	Day	29% 14% 34% 15% 7% 1	270
	21st to end	Day	25% 16% 43% 14% 1	207
December	1st to 10th	Day	26% 19% 36% 13% 4 2	180
	11th to 20th	Day	23% 23% 37% 14% 2	180
	21st to end	Day	29% 22% 34% 12% 2	283
January	1st to 10th	Night	25% 16% 34% 20% 5%	760
	11th to 20th	Night	29% 15% 34% 17% 4	760
	21st to end	Night	26% 16% 31% 24% 4	800
February	1st to 10th	Night	29% 12% 35% 22% 2	720
	11th to 20th	Night	26% 14% 35% 23% 2	703
	21st to end	Night	27% 13% 38% 19% 3	592
March	1st to 10th	Night	23% 13% 34% 25% 5%	720
	11th to 20th	Night	20% 13% 34% 26% 6% 1	720
	21st to end	Night	25% 10% 31% 27% 7% 1	792
April	1st to 10th	Night	20% 12% 36% 27% 5% 1	720
	11th to 20th	Night	19% 12% 31% 26% 11% 1	561
	21st to end	Night	18% 8% 32% 34% 6% 1	540
May	1st to 10th	Night	21% 6% 28% 34% 10% 1	540
	11th to 20th	Night	20% 6% 24% 36% 12% 2	531
	21st to end	Night	11% 2 17% 41% 26% 3	584
June	1st to 10th	Night	10% 4 21% 45% 20%	473
	11th to 20th	Night	13% 3 20% 46% 17% 1	360
	21st to end	Night	11% 2 21% 43% 22% 1	522
July	1st to 10th	Night	10% 2 12% 41% 30% 6%	525
	11th to 20th	Night	7% 3 16% 41% 30% 5%	522
	21st to end	Night	8% 3 12% 44% 30% 2	591
August	1st to 10th	Night	8% 2 11% 44% 32% 3	537
	11th to 20th	Night	9% 3 11% 42% 30% 6%	534
	21st to end	Night	9% 2 15% 34% 35% 6%	602
September	1st to 10th	Night	12% 4 18% 32% 29% 5%	720
	11th to 20th	Night	13% 2 12% 34% 35% 5%	720
	21st to end	Night	16% 5% 23% 31% 21% 4	720
October	1st to 10th	Night	15% 7% 19% 37% 18% 3	720
	11th to 20th	Night	20% 9% 30% 27% 12% 1	720
	21st to end	Night	26% 11% 27% 28% 7%	792
November	1st to 10th	Night	19% 8% 29% 30% 12% 1	740
	11th to 20th	Night	23% 13% 32% 23% 8% 1	760
	21st to end	Night	27% 10% 33% 24% 6% 1	760
December	1st to 10th	Night	31% 13% 30% 22% 4	760
	11th to 20th	Night	25% 12% 35% 23% 4	760
	21st to end	Night	27% 14% 33% 23% 3	836

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