Lake Erie Metropark
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Erie Metropark clear sky chart from 2005-11-06 to 2025-07-21.

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	13% 9% 3 8% 6% 5% 5% 4 6% 7% 34%	119341
	Night	15% 10% 4 8% 5% 4 4 4 5% 7% 34%	119773
Transparency	Day	46% 7% 13% 20% 12% 1	122968
	Night	48% 6% 12% 20% 13% 1	124270
Seeing	Day	15% 8% 25% 28% 17% 5%	16318
	Night	18% 7% 28% 30% 14% 2	26294

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	11% 13% 6% 15% 8% 5% 5% 3 5% 6% 23%	3617
	11th to 20th	Day	13% 14% 5% 15% 8% 7% 7% 5% 6% 6% 13%	3688
	21st to end	Day	22% 15% 6% 13% 7% 5% 4 4 5% 5% 16%	4466
February	1st to 10th	Day	15% 14% 4 11% 7% 6% 5% 5% 5% 4 23%	1800
	11th to 20th	Day	14% 11% 4 12% 8% 7% 6% 3 5% 7% 24%	1889
	21st to end	Day	16% 11% 4 10% 6% 6% 5% 4 5% 6% 28%	1650
March	1st to 10th	Day	15% 11% 5% 10% 7% 5% 5% 3 5% 5% 29%	4615
	11th to 20th	Day	11% 9% 3 8% 6% 6% 5% 4 5% 7% 36%	4980
	21st to end	Day	15% 11% 4 11% 6% 5% 5% 3 5% 7% 28%	5465
April	1st to 10th	Day	14% 11% 3 7% 6% 5% 5% 4 6% 6% 33%	2304
	11th to 20th	Day	17% 7% 2 7% 5% 5% 6% 5% 5% 7% 34%	2541
	21st to end	Day	17% 8% 3 7% 5% 4 4 4 5% 7% 37%	2600
May	1st to 10th	Day	18% 9% 3 8% 5% 5% 4 3 5% 6% 33%	5862
	11th to 20th	Day	15% 8% 3 6% 4 4 5% 4 7% 9% 34%	5861
	21st to end	Day	13% 6% 2 6% 4 4 4 3 6% 8% 42%	6433
June	1st to 10th	Day	9% 7% 2 6% 5% 5% 5% 5% 7% 9% 41%	2724
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 5% 7% 9% 41%	2800
	21st to end	Day	8% 5% 2 5% 6% 5% 5% 5% 8% 10% 40%	2800
July	1st to 10th	Day	10% 5% 2 6% 4 5% 5% 5% 6% 10% 42%	4580
	11th to 20th	Day	7% 4 2 5% 5% 4 5% 4 7% 10% 47%	4562
	21st to end	Day	6% 5% 2 7% 5% 5% 6% 4 7% 9% 43%	4466
August	1st to 10th	Day	10% 5% 2 5% 4 4 5% 5% 6% 9% 45%	4104
	11th to 20th	Day	8% 5% 2 6% 5% 5% 7% 5% 8% 10% 38%	4044
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 4 8% 11% 40%	4500
September	1st to 10th	Day	9% 6% 3 6% 4 4 5% 4 7% 7% 45%	2133
	11th to 20th	Day	8% 5% 1 5% 4 4 5% 5% 6% 8% 48%	2090
	21st to end	Day	15% 6% 3 7% 4 3 4 4 6% 8% 40%	2090
October	1st to 10th	Day	12% 5% 3 6% 5% 5% 4 3 5% 9% 44%	2032
	11th to 20th	Day	16% 9% 2 7% 5% 5% 5% 4 5% 7% 35%	1900
	21st to end	Day	19% 8% 3 7% 5% 5% 5% 5% 5% 7% 32%	1961
November	1st to 10th	Day	10% 8% 3 7% 6% 4 4 4 6% 8% 40%	1762
	11th to 20th	Day	14% 13% 3 7% 6% 5% 5% 4 5% 6% 32%	1800
	21st to end	Day	18% 12% 4 9% 5% 4 4 3 6% 7% 27%	1720
December	1st to 10th	Day	13% 13% 6% 13% 7% 6% 6% 4 5% 6% 22%	2600
	11th to 20th	Day	19% 18% 4 10% 6% 5% 5% 4 5% 5% 18%	2920
	21st to end	Day	24% 18% 6% 13% 6% 5% 3 3 4 4 14%	3982
January	1st to 10th	Night	13% 13% 6% 12% 6% 5% 5% 4 5% 6% 26%	6348
	11th to 20th	Night	12% 17% 7% 12% 7% 5% 5% 4 7% 7% 16%	6271
	21st to end	Night	20% 15% 7% 10% 5% 4 4 3 4 5% 24%	6490
February	1st to 10th	Night	16% 14% 5% 12% 6% 5% 5% 4 4 5% 24%	2600
	11th to 20th	Night	15% 13% 4 8% 7% 5% 4 4 5% 6% 27%	2392
	21st to end	Night	19% 11% 4 10% 5% 4 4 3 6% 6% 29%	1980
March	1st to 10th	Night	14% 11% 4 8% 4 4 4 3 5% 6% 35%	5236
	11th to 20th	Night	10% 7% 2 6% 5% 4 5% 4 6% 8% 43%	4980
	21st to end	Night	15% 9% 3 8% 5% 5% 4 3 5% 6% 37%	5467
April	1st to 10th	Night	16% 10% 4 7% 4 5% 4 4 5% 7% 35%	2113
	11th to 20th	Night	17% 8% 2 6% 4 4 5% 4 6% 6% 37%	1807
	21st to end	Night	16% 8% 3 6% 4 4 4 4 5% 7% 39%	1800
May	1st to 10th	Night	20% 10% 3 9% 5% 5% 5% 3 4 6% 31%	4033
	11th to 20th	Night	16% 8% 3 8% 5% 4 4 3 5% 6% 36%	4032
	21st to end	Night	13% 5% 2 6% 4 5% 4 4 6% 8% 44%	4421
June	1st to 10th	Night	12% 4 2 5% 4 5% 4 5% 6% 9% 44%	1670
	11th to 20th	Night	10% 5% 2 6% 4 5% 4 5% 7% 9% 42%	1544
	21st to end	Night	10% 4 2 6% 5% 4 4 5% 7% 8% 46%	1600
July	1st to 10th	Night	8% 3 2 4 4 3 5% 4 6% 10% 50%	2610
	11th to 20th	Night	8% 4 2 5% 4 3 4 4 6% 10% 50%	2623
	21st to end	Night	5% 4 2 6% 4 5% 5% 5% 8% 9% 47%	3087
August	1st to 10th	Night	11% 6% 2 5% 4 4 4 4 6% 9% 45%	2825
	11th to 20th	Night	7% 5% 2 5% 4 4 5% 4 6% 8% 49%	2785
	21st to end	Night	7% 4 2 6% 4 5% 6% 4 7% 8% 47%	3152
September	1st to 10th	Night	9% 5% 2 6% 5% 4 4 4 6% 7% 48%	2027
	11th to 20th	Night	9% 4 1 5% 4 4 4 3 4 7% 55%	2090
	21st to end	Night	15% 6% 2 7% 4 4 4 3 5% 6% 43%	2090
October	1st to 10th	Night	13% 5% 3 6% 4 4 4 3 6% 6% 47%	2147
	11th to 20th	Night	16% 8% 2 7% 5% 5% 4 4 5% 6% 37%	2280
	21st to end	Night	20% 8% 2 7% 4 5% 3 3 5% 7% 35%	2635
November	1st to 10th	Night	13% 7% 2 6% 4 4 4 3 5% 7% 43%	2536
	11th to 20th	Night	16% 9% 3 8% 6% 5% 4 4 6% 7% 31%	2600
	21st to end	Night	20% 13% 4 8% 4 4 4 3 5% 7% 28%	2675
December	1st to 10th	Night	13% 13% 5% 12% 8% 6% 5% 4 5% 6% 24%	4580
	11th to 20th	Night	16% 17% 5% 11% 6% 5% 5% 3 4 6% 21%	5251
	21st to end	Night	27% 18% 6% 11% 5% 4 3 3 4 4 15%	6996

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	61% 7% 10% 15% 7% 1	3618
	11th to 20th	Day	68% 7% 9% 7% 9%	3688
	21st to end	Day	69% 5% 10% 9% 6%	4466
February	1st to 10th	Day	60% 7% 12% 14% 7%	1800
	11th to 20th	Day	60% 6% 12% 16% 7% 1	1899
	21st to end	Day	53% 8% 14% 17% 7% 2	1650
March	1st to 10th	Day	55% 6% 14% 18% 8% 1	4615
	11th to 20th	Day	44% 6% 17% 22% 9% 1	4980
	21st to end	Day	53% 7% 12% 16% 11%	5465
April	1st to 10th	Day	49% 8% 12% 17% 13% 1	2304
	11th to 20th	Day	46% 7% 12% 20% 12% 2	2541
	21st to end	Day	45% 7% 14% 21% 12% 2	2600
May	1st to 10th	Day	49% 7% 11% 18% 13% 2	5897
	11th to 20th	Day	43% 8% 14% 21% 11% 2	5865
	21st to end	Day	39% 7% 10% 22% 17% 5%	6447
June	1st to 10th	Day	36% 8% 14% 26% 13% 2	2724
	11th to 20th	Day	35% 9% 15% 22% 17% 2	2800
	21st to end	Day	34% 10% 15% 21% 17% 2	2800
July	1st to 10th	Day	37% 7% 14% 23% 18% 2	4511
	11th to 20th	Day	29% 7% 14% 31% 17% 1	4487
	21st to end	Day	34% 8% 17% 18% 21% 3	4324
August	1st to 10th	Day	33% 9% 16% 28% 14% 1	4091
	11th to 20th	Day	35% 9% 14% 32% 10% 1	4083
	21st to end	Day	33% 9% 15% 29% 12% 1	4499
September	1st to 10th	Day	35% 9% 16% 22% 16% 2	2133
	11th to 20th	Day	30% 9% 14% 30% 16% 1	2090
	21st to end	Day	40% 8% 13% 24% 14%	2090
October	1st to 10th	Day	29% 5% 13% 32% 20% 1	3370
	11th to 20th	Day	39% 5% 11% 27% 18%	3140
	21st to end	Day	41% 6% 15% 23% 14% 1	3211
November	1st to 10th	Day	41% 7% 14% 24% 13% 1	1762
	11th to 20th	Day	52% 6% 14% 19% 9% 1	1800
	21st to end	Day	55% 6% 14% 17% 7%	1720
December	1st to 10th	Day	61% 8% 16% 11% 4	2600
	11th to 20th	Day	66% 7% 10% 13% 4	2916
	21st to end	Day	74% 5% 8% 8% 5%	3982
January	1st to 10th	Night	58% 6% 10% 18% 7% 1	6348
	11th to 20th	Night	65% 8% 11% 9% 7% 1	6271
	21st to end	Night	62% 6% 12% 11% 10%	6490
February	1st to 10th	Night	61% 6% 11% 14% 7% 1	2600
	11th to 20th	Night	57% 5% 11% 18% 8% 1	2393
	21st to end	Night	55% 6% 12% 17% 8% 2	1980
March	1st to 10th	Night	49% 4 14% 22% 11% 1	5236
	11th to 20th	Night	37% 6% 15% 26% 15% 1	4980
	21st to end	Night	47% 6% 12% 19% 15% 1	5467
April	1st to 10th	Night	49% 6% 10% 20% 13% 2	2113
	11th to 20th	Night	45% 6% 11% 19% 17% 2	1807
	21st to end	Night	43% 6% 13% 20% 16% 3	1800
May	1st to 10th	Night	53% 7% 9% 14% 15% 2	4060
	11th to 20th	Night	45% 7% 11% 25% 10% 2	4033
	21st to end	Night	38% 5% 13% 23% 19% 3	4429
June	1st to 10th	Night	35% 7% 11% 27% 18% 3	1670
	11th to 20th	Night	36% 8% 13% 25% 16% 3	1544
	21st to end	Night	33% 8% 12% 25% 21% 1	1600
July	1st to 10th	Night	29% 5% 13% 31% 15% 6%	2570
	11th to 20th	Night	28% 7% 15% 30% 18% 2	2575
	21st to end	Night	30% 8% 19% 19% 22% 2	2988
August	1st to 10th	Night	35% 7% 11% 28% 17% 2	2814
	11th to 20th	Night	32% 8% 12% 33% 14% 2	2812
	21st to end	Night	33% 7% 13% 30% 15% 2	3152
September	1st to 10th	Night	34% 8% 12% 26% 17% 3	2027
	11th to 20th	Night	29% 6% 11% 30% 21% 2	2090
	21st to end	Night	41% 6% 12% 24% 15% 1	2090
October	1st to 10th	Night	26% 5% 9% 32% 27% 1	3576
	11th to 20th	Night	40% 5% 11% 25% 18% 1	3779
	21st to end	Night	38% 4 11% 30% 16% 1	4335
November	1st to 10th	Night	40% 6% 13% 25% 15% 1	2536
	11th to 20th	Night	51% 6% 12% 19% 10% 1	2600
	21st to end	Night	57% 5% 13% 19% 6%	2675
December	1st to 10th	Night	60% 7% 14% 15% 4	4580
	11th to 20th	Night	63% 6% 13% 12% 6% 1	5254
	21st to end	Night	72% 6% 9% 8% 5%	6996

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	20% 13% 33% 26% 8% 1	300
	11th to 20th	Day	21% 11% 42% 21% 4 1	300
	21st to end	Day	27% 12% 28% 28% 5%	330
February	1st to 10th	Day	23% 13% 38% 21% 4 1	300
	11th to 20th	Day	18% 19% 34% 21% 6%	300
	21st to end	Day	20% 17% 40% 18% 4	249
March	1st to 10th	Day	17% 15% 36% 26% 6%	357
	11th to 20th	Day	18% 12% 33% 29% 7% 1	500
	21st to end	Day	22% 11% 33% 26% 7% 1	550
April	1st to 10th	Day	16% 10% 35% 30% 8% 1	500
	11th to 20th	Day	20% 13% 29% 24% 9% 4	492
	21st to end	Day	18% 9% 34% 26% 12% 2	500
May	1st to 10th	Day	23% 8% 28% 26% 12% 3	503
	11th to 20th	Day	18% 5% 27% 26% 19% 5%	527
	21st to end	Day	13% 3 22% 33% 22% 8%	573
June	1st to 10th	Day	11% 6% 22% 39% 19% 4	654
	11th to 20th	Day	11% 3 23% 38% 22% 3	730
	21st to end	Day	11% 4 21% 35% 24% 5%	730
July	1st to 10th	Day	8% 2 17% 33% 28% 12%	721
	11th to 20th	Day	9% 3 17% 36% 25% 9%	713
	21st to end	Day	7% 5% 12% 34% 33% 9%	532
August	1st to 10th	Day	9% 3 15% 31% 28% 15%	486
	11th to 20th	Day	12% 3 14% 30% 30% 11%	479
	21st to end	Day	9% 3 15% 27% 35% 12%	539
September	1st to 10th	Day	11% 3 18% 27% 28% 12%	490
	11th to 20th	Day	7% 4 14% 25% 34% 16%	490
	21st to end	Day	18% 8% 19% 25% 21% 9%	490
October	1st to 10th	Day	11% 6% 23% 29% 22% 9%	490
	11th to 20th	Day	17% 13% 29% 25% 13% 3	490
	21st to end	Day	23% 11% 33% 22% 10% 1	410
November	1st to 10th	Day	13% 11% 31% 26% 15% 3	300
	11th to 20th	Day	18% 19% 30% 24% 8% 1	300
	21st to end	Day	24% 12% 35% 24% 5%	260
December	1st to 10th	Day	17% 19% 32% 23% 10% 1	200
	11th to 20th	Day	23% 17% 36% 20% 3	203
	21st to end	Day	25% 16% 34% 21% 4	330
January	1st to 10th	Night	23% 12% 36% 22% 6% 1	1000
	11th to 20th	Night	27% 12% 32% 24% 5%	963
	21st to end	Night	21% 9% 35% 29% 5%	880
February	1st to 10th	Night	24% 7% 37% 28% 4	800
	11th to 20th	Night	22% 10% 35% 29% 4	783
	21st to end	Night	23% 10% 40% 24% 2	660
March	1st to 10th	Night	19% 9% 36% 29% 7%	800
	11th to 20th	Night	18% 10% 36% 29% 7% 1	800
	21st to end	Night	21% 9% 32% 29% 9% 1	880
April	1st to 10th	Night	20% 11% 35% 30% 5% 1	713
	11th to 20th	Night	19% 8% 34% 27% 10% 2	593
	21st to end	Night	20% 7% 31% 33% 9%	600
May	1st to 10th	Night	20% 5% 31% 31% 12% 1	600
	11th to 20th	Night	22% 4 26% 32% 15% 2	591
	21st to end	Night	11% 3 20% 39% 24% 4	650
June	1st to 10th	Night	12% 4 21% 43% 19% 1	600
	11th to 20th	Night	12% 3 17% 44% 23% 1	544
	21st to end	Night	11% 2 20% 43% 21% 4	600
July	1st to 10th	Night	8% 2 13% 37% 35% 5%	585
	11th to 20th	Night	9% 3 14% 40% 27% 7%	582
	21st to end	Night	6% 3 13% 44% 30% 4	624
August	1st to 10th	Night	9% 1 13% 43% 28% 5%	567
	11th to 20th	Night	10% 2 14% 35% 33% 5%	564
	21st to end	Night	10% 2 14% 35% 33% 6%	627
September	1st to 10th	Night	12% 4 16% 34% 29% 6%	697
	11th to 20th	Night	10% 3 15% 30% 35% 6%	760
	21st to end	Night	17% 5% 19% 31% 23% 5%	760
October	1st to 10th	Night	15% 6% 25% 30% 19% 5%	760
	11th to 20th	Night	20% 11% 31% 25% 11% 3	760
	21st to end	Night	24% 9% 31% 29% 8%	836
November	1st to 10th	Night	16% 10% 31% 29% 12% 2	780
	11th to 20th	Night	22% 14% 33% 23% 9% 1	800
	21st to end	Night	27% 10% 34% 23% 7%	800
December	1st to 10th	Night	23% 14% 34% 22% 6% 1	800
	11th to 20th	Night	22% 12% 38% 23% 5%	835
	21st to end	Night	30% 10% 32% 24% 4	1100

Page generated at 2025-07-18 01:10:02. Version ac07

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