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 2025-01-22.

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% 11% 4 9% 5% 5% 5% 4 5% 7% 31%	104780
	Night	15% 12% 4 9% 5% 4 4 3 5% 6% 32%	104501
Transparency	Day	50% 6% 11% 20% 11% 1	108469
	Night	50% 5% 11% 21% 12% 2	108951
Seeing	Day	20% 12% 27% 21% 14% 6%	14868
	Night	20% 9% 27% 30% 13% 2	25023

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% 21% 6% 14% 5% 4 3 3 5% 5% 16%	2926
	11th to 20th	Day	14% 22% 7% 12% 5% 5% 4 4 5% 5% 16%	2930
	21st to end	Day	26% 20% 10% 12% 6% 4 3 3 3 3 10%	3133
February	1st to 10th	Day	18% 17% 6% 10% 7% 4 4 3 4 5% 22%	1710
	11th to 20th	Day	15% 13% 4 14% 7% 5% 5% 3 4 5% 23%	1750
	21st to end	Day	17% 15% 4 10% 5% 4 4 3 5% 5% 27%	1570
March	1st to 10th	Day	22% 15% 5% 8% 5% 4 4 3 4 6% 25%	3334
	11th to 20th	Day	12% 12% 4 11% 5% 5% 4 3 4 5% 34%	3480
	21st to end	Day	21% 9% 4 9% 5% 4 3 4 5% 6% 30%	3815
April	1st to 10th	Day	12% 13% 4 9% 5% 5% 4 5% 5% 7% 31%	2104
	11th to 20th	Day	17% 10% 3 8% 5% 5% 4 3 4 6% 34%	2429
	21st to end	Day	18% 10% 3 8% 5% 4 4 4 5% 6% 32%	2470
May	1st to 10th	Day	20% 10% 3 8% 6% 5% 5% 4 5% 6% 29%	4082
	11th to 20th	Day	19% 8% 3 7% 5% 4 4 3 6% 8% 33%	4081
	21st to end	Day	11% 6% 2 7% 5% 5% 6% 5% 6% 9% 38%	4476
June	1st to 10th	Day	11% 7% 3 7% 5% 5% 5% 4 7% 9% 36%	2532
	11th to 20th	Day	13% 6% 3 7% 5% 4 5% 4 8% 9% 36%	2660
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 5% 8% 9% 38%	2475
July	1st to 10th	Day	10% 6% 3 8% 5% 5% 5% 5% 7% 10% 37%	4120
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 5% 8% 10% 41%	4120
	21st to end	Day	10% 6% 3 7% 5% 5% 6% 5% 7% 9% 37%	4466
August	1st to 10th	Day	11% 8% 3 8% 5% 6% 5% 5% 7% 9% 34%	4104
	11th to 20th	Day	9% 7% 2 6% 5% 5% 6% 5% 8% 10% 36%	4044
	21st to end	Day	7% 5% 2 6% 5% 6% 6% 5% 7% 9% 40%	4477
September	1st to 10th	Day	13% 5% 2 5% 5% 4 4 4 6% 7% 45%	2142
	11th to 20th	Day	9% 7% 2 5% 6% 4 5% 4 6% 9% 43%	2090
	21st to end	Day	19% 8% 3 6% 4 4 4 3 4 7% 38%	2090
October	1st to 10th	Day	14% 7% 3 6% 4 5% 4 3 6% 7% 41%	1985
	11th to 20th	Day	16% 9% 3 7% 4 4 4 4 5% 6% 37%	1900
	21st to end	Day	20% 11% 3 7% 5% 5% 4 3 4 6% 32%	2074
November	1st to 10th	Day	10% 9% 3 8% 5% 5% 3 3 5% 6% 42%	1762
	11th to 20th	Day	16% 13% 4 8% 6% 4 4 3 4 6% 30%	1800
	21st to end	Day	16% 16% 5% 10% 6% 6% 4 3 5% 5% 24%	1662
December	1st to 10th	Day	18% 14% 5% 15% 5% 4 3 3 4 4 24%	2600
	11th to 20th	Day	22% 17% 6% 12% 4 3 3 2 4 5% 20%	2990
	21st to end	Day	22% 22% 6% 13% 6% 5% 4 3 3 4 12%	4397
January	1st to 10th	Night	16% 20% 7% 14% 6% 5% 4 4 4 4 17%	4239
	11th to 20th	Night	13% 20% 9% 17% 6% 5% 5% 4 4 4 13%	4250
	21st to end	Night	25% 19% 7% 14% 5% 3 3 2 3 3 15%	4546
February	1st to 10th	Night	20% 15% 5% 11% 6% 5% 4 3 4 5% 23%	2470
	11th to 20th	Night	16% 15% 5% 9% 6% 5% 4 3 6% 6% 24%	2314
	21st to end	Night	18% 14% 5% 12% 7% 4 4 3 5% 5% 24%	1884
March	1st to 10th	Night	22% 14% 4 7% 4 4 3 2 4 5% 33%	3519
	11th to 20th	Night	15% 10% 3 6% 5% 4 5% 4 6% 7% 37%	3480
	21st to end	Night	17% 11% 3 7% 5% 4 4 3 4 6% 36%	3817
April	1st to 10th	Night	15% 13% 3 7% 5% 5% 4 3 5% 6% 34%	2076
	11th to 20th	Night	16% 9% 4 8% 5% 4 4 4 6% 7% 35%	1716
	21st to end	Night	15% 9% 3 6% 5% 5% 5% 4 5% 7% 37%	1710
May	1st to 10th	Night	23% 11% 3 7% 5% 5% 3 4 5% 6% 27%	2813
	11th to 20th	Night	18% 8% 3 6% 4 3 4 3 5% 7% 39%	2812
	21st to end	Night	9% 6% 2 5% 4 4 5% 4 6% 11% 44%	3079
June	1st to 10th	Night	9% 7% 2 7% 5% 5% 4 3 6% 7% 44%	1639
	11th to 20th	Night	8% 6% 2 6% 4 4 5% 5% 7% 10% 41%	1520
	21st to end	Night	9% 6% 2 5% 5% 4 5% 4 7% 9% 43%	1692
July	1st to 10th	Night	10% 6% 2 7% 4 3 4 3 6% 8% 47%	2840
	11th to 20th	Night	9% 4 1 6% 4 4 5% 4 7% 9% 48%	2840
	21st to end	Night	6% 6% 3 7% 6% 4 5% 4 6% 9% 44%	3087
August	1st to 10th	Night	10% 8% 3 8% 5% 5% 5% 4 7% 9% 37%	2825
	11th to 20th	Night	10% 8% 2 8% 4 4 4 3 5% 7% 43%	2785
	21st to end	Night	6% 4 2 6% 4 6% 6% 5% 6% 8% 47%	3146
September	1st to 10th	Night	12% 5% 2 6% 4 3 4 3 4 7% 50%	2035
	11th to 20th	Night	9% 4 2 4 3 3 4 4 6% 8% 54%	2090
	21st to end	Night	15% 8% 3 6% 4 3 4 3 5% 6% 43%	2090
October	1st to 10th	Night	12% 6% 2 6% 4 4 4 4 6% 7% 45%	2194
	11th to 20th	Night	15% 9% 2 7% 5% 4 4 3 5% 7% 38%	2280
	21st to end	Night	21% 9% 3 6% 4 4 4 3 5% 7% 34%	2522
November	1st to 10th	Night	13% 8% 2 5% 4 4 5% 4 5% 7% 43%	2536
	11th to 20th	Night	16% 13% 4 7% 5% 4 4 3 6% 6% 32%	2600
	21st to end	Night	19% 14% 4 8% 5% 4 4 4 5% 6% 27%	2733
December	1st to 10th	Night	17% 15% 5% 12% 6% 5% 4 4 4 6% 23%	4580
	11th to 20th	Night	19% 17% 7% 12% 5% 4 3 3 4 5% 20%	5205
	21st to end	Night	21% 21% 7% 12% 5% 5% 4 2 4 5% 14%	6537

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	70% 4 9% 13% 3	2927
	11th to 20th	Day	70% 3 10% 11% 6%	2930
	21st to end	Day	80% 4 6% 7% 2	3133
February	1st to 10th	Day	65% 5% 8% 15% 7% 1	1710
	11th to 20th	Day	63% 6% 7% 16% 8% 1	1759
	21st to end	Day	59% 3 13% 15% 8% 2	1570
March	1st to 10th	Day	61% 4 9% 21% 5%	3334
	11th to 20th	Day	52% 6% 9% 25% 8% 1	3480
	21st to end	Day	55% 5% 10% 18% 11% 1	3815
April	1st to 10th	Day	52% 6% 13% 17% 12% 1	2104
	11th to 20th	Day	51% 5% 11% 17% 14% 2	2429
	21st to end	Day	52% 6% 10% 20% 10% 2	2470
May	1st to 10th	Day	55% 6% 10% 21% 8% 1	4120
	11th to 20th	Day	49% 6% 12% 22% 9% 1	4085
	21st to end	Day	39% 9% 13% 21% 13% 5%	4489
June	1st to 10th	Day	42% 8% 11% 25% 13% 1	2532
	11th to 20th	Day	43% 7% 13% 22% 13% 1	2660
	21st to end	Day	39% 8% 13% 23% 15% 2	2475
July	1st to 10th	Day	42% 6% 12% 23% 16% 2	4055
	11th to 20th	Day	35% 7% 13% 25% 19% 1	4051
	21st to end	Day	41% 7% 14% 17% 18% 3	4324
August	1st to 10th	Day	45% 7% 13% 22% 12%	4091
	11th to 20th	Day	39% 8% 11% 30% 11% 1	4083
	21st to end	Day	38% 7% 14% 29% 11% 2	4477
September	1st to 10th	Day	38% 6% 13% 22% 18% 4	2142
	11th to 20th	Day	36% 7% 13% 26% 16% 3	2090
	21st to end	Day	47% 6% 10% 21% 16% 1	2090
October	1st to 10th	Day	32% 5% 12% 31% 20% 1	3297
	11th to 20th	Day	42% 4 11% 23% 16% 4	3140
	21st to end	Day	40% 4 12% 26% 17% 1	3400
November	1st to 10th	Day	42% 5% 11% 24% 15% 2	1762
	11th to 20th	Day	55% 4 9% 19% 10% 2	1800
	21st to end	Day	61% 5% 9% 17% 6% 1	1662
December	1st to 10th	Day	65% 4 13% 14% 4	2600
	11th to 20th	Day	68% 3 10% 15% 5%	2986
	21st to end	Day	78% 3 7% 8% 4	4397
January	1st to 10th	Night	70% 5% 8% 13% 4	4239
	11th to 20th	Night	75% 4 9% 10% 3	4250
	21st to end	Night	76% 3 6% 11% 3	4546
February	1st to 10th	Night	63% 5% 11% 15% 6%	2470
	11th to 20th	Night	59% 5% 11% 16% 8% 1	2316
	21st to end	Night	63% 5% 9% 13% 9% 2	1884
March	1st to 10th	Night	55% 4 10% 20% 10%	3519
	11th to 20th	Night	44% 8% 12% 26% 8% 2	3480
	21st to end	Night	49% 5% 9% 26% 10% 1	3817
April	1st to 10th	Night	50% 6% 11% 18% 14% 2	2076
	11th to 20th	Night	47% 6% 11% 17% 15% 3	1716
	21st to end	Night	46% 5% 11% 20% 15% 2	1710
May	1st to 10th	Night	56% 6% 9% 19% 8% 1	2840
	11th to 20th	Night	44% 7% 11% 24% 13% 2	2813
	21st to end	Night	33% 8% 14% 27% 15% 4	3087
June	1st to 10th	Night	39% 6% 10% 24% 18% 3	1639
	11th to 20th	Night	35% 9% 14% 23% 18% 2	1520
	21st to end	Night	35% 8% 13% 25% 17% 2	1692
July	1st to 10th	Night	36% 5% 12% 24% 18% 5%	2795
	11th to 20th	Night	31% 6% 13% 32% 17% 1	2786
	21st to end	Night	36% 6% 13% 20% 22% 2	2988
August	1st to 10th	Night	42% 6% 13% 23% 14% 1	2814
	11th to 20th	Night	40% 6% 11% 26% 17% 1	2812
	21st to end	Night	33% 6% 15% 31% 14% 2	3146
September	1st to 10th	Night	33% 6% 11% 26% 19% 4	2035
	11th to 20th	Night	28% 7% 11% 26% 26% 2	2090
	21st to end	Night	42% 5% 10% 22% 19% 2	2090
October	1st to 10th	Night	30% 4 8% 30% 27% 1	3662
	11th to 20th	Night	37% 5% 13% 24% 18% 4	3779
	21st to end	Night	37% 3 10% 29% 19% 2	4146
November	1st to 10th	Night	40% 4 12% 24% 16% 3	2536
	11th to 20th	Night	52% 4 11% 20% 11% 2	2600
	21st to end	Night	59% 4 12% 18% 6% 1	2733
December	1st to 10th	Night	63% 4 11% 18% 4	4580
	11th to 20th	Night	66% 4 13% 14% 3	5208
	21st to end	Night	73% 4 10% 11% 3	6537

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	25% 22% 37% 11% 4 1	300
	11th to 20th	Day	28% 25% 36% 8% 2 1	300
	21st to end	Day	28% 23% 34% 13% 2	300
February	1st to 10th	Day	28% 20% 36% 13% 3	270
	11th to 20th	Day	29% 28% 33% 9% 2	270
	21st to end	Day	29% 29% 31% 11%	225
March	1st to 10th	Day	27% 18% 30% 21% 4	393
	11th to 20th	Day	26% 13% 36% 17% 6% 1	460
	21st to end	Day	32% 15% 27% 22% 4	506
April	1st to 10th	Day	22% 17% 33% 18% 8% 2	460
	11th to 20th	Day	24% 18% 26% 18% 9% 5%	452
	21st to end	Day	23% 14% 32% 19% 10% 2	460
May	1st to 10th	Day	25% 15% 27% 20% 9% 3	463
	11th to 20th	Day	20% 10% 31% 20% 14% 6%	487
	21st to end	Day	13% 6% 24% 27% 22% 8%	529
June	1st to 10th	Day	13% 7% 28% 30% 16% 5%	490
	11th to 20th	Day	16% 9% 20% 29% 21% 5%	490
	21st to end	Day	12% 6% 29% 27% 20% 6%	490
July	1st to 10th	Day	13% 3 19% 26% 24% 16%	485
	11th to 20th	Day	12% 4 22% 26% 24% 12%	484
	21st to end	Day	11% 4 19% 25% 28% 12%	532
August	1st to 10th	Day	12% 4 16% 29% 25% 14%	486
	11th to 20th	Day	13% 5% 20% 28% 22% 12%	479
	21st to end	Day	9% 5% 14% 29% 25% 18%	539
September	1st to 10th	Day	12% 5% 20% 25% 23% 14%	490
	11th to 20th	Day	10% 3 15% 24% 31% 17%	490
	21st to end	Day	25% 8% 21% 21% 16% 9%	490
October	1st to 10th	Day	12% 9% 25% 26% 21% 7%	490
	11th to 20th	Day	18% 14% 32% 23% 9% 4	490
	21st to end	Day	27% 13% 32% 20% 7% 1	523
November	1st to 10th	Day	16% 16% 38% 17% 11% 2	300
	11th to 20th	Day	30% 13% 34% 15% 7% 1	300
	21st to end	Day	26% 17% 41% 14% 1	230
December	1st to 10th	Day	26% 18% 37% 14% 5% 2	200
	11th to 20th	Day	27% 22% 35% 14% 3	200
	21st to end	Day	29% 22% 33% 14% 2	315
January	1st to 10th	Night	25% 16% 34% 20% 5%	800
	11th to 20th	Night	28% 16% 35% 17% 4	800
	21st to end	Night	27% 16% 31% 23% 3	841
February	1st to 10th	Night	27% 13% 34% 23% 3	760
	11th to 20th	Night	25% 15% 35% 23% 2	743
	21st to end	Night	27% 13% 37% 20% 3	628
March	1st to 10th	Night	23% 13% 33% 25% 5%	760
	11th to 20th	Night	20% 14% 34% 26% 6% 1	760
	21st to end	Night	25% 10% 31% 26% 6% 1	836
April	1st to 10th	Night	21% 12% 36% 26% 4 1	760
	11th to 20th	Night	19% 12% 31% 26% 10% 1	592
	21st to end	Night	18% 8% 32% 34% 6% 1	570
May	1st to 10th	Night	21% 7% 28% 34% 10% 1	570
	11th to 20th	Night	20% 6% 24% 37% 12% 2	561
	21st to end	Night	11% 2 17% 42% 25% 3	617
June	1st to 10th	Night	10% 5% 21% 44% 20%	499
	11th to 20th	Night	12% 3 20% 47% 17% 1	380
	21st to end	Night	11% 2 22% 42% 22% 1	552
July	1st to 10th	Night	10% 2 12% 41% 28% 6%	555
	11th to 20th	Night	7% 3 16% 41% 29% 4	552
	21st to end	Night	8% 3 12% 45% 30% 2	624
August	1st to 10th	Night	8% 2 11% 44% 31% 3	567
	11th to 20th	Night	10% 3 12% 42% 28% 5%	564
	21st to end	Night	8% 3 14% 34% 36% 6%	636
September	1st to 10th	Night	12% 4 18% 34% 28% 5%	760
	11th to 20th	Night	12% 2 11% 35% 35% 5%	760
	21st to end	Night	17% 6% 23% 30% 20% 4	760
October	1st to 10th	Night	14% 7% 20% 37% 19% 3	760
	11th to 20th	Night	20% 9% 30% 27% 12% 2	760
	21st to end	Night	25% 11% 27% 29% 8%	836
November	1st to 10th	Night	18% 8% 29% 32% 12% 1	780
	11th to 20th	Night	23% 12% 32% 24% 8% 1	800
	21st to end	Night	27% 10% 33% 24% 6% 1	800
December	1st to 10th	Night	30% 13% 31% 21% 5%	800
	11th to 20th	Night	26% 12% 34% 23% 4	800
	21st to end	Night	27% 15% 32% 24% 3	880

Page generated at 2025-01-19 03:06:46. Version ac07

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