Conneaut
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Conneaut clear sky chart from 2005-11-06 to 2026-06-16.

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	17% 12% 4 9% 5% 4 4 3 5% 6% 31%	137590
	Night	17% 15% 5% 10% 5% 4 4 3 4 6% 27%	134409
Transparency	Day	53% 6% 11% 19% 10% 1	141192
	Night	58% 5% 10% 17% 10% 1	138878
Seeing	Day	23% 16% 29% 20% 9% 3	16570
	Night	25% 15% 26% 23% 10% 1	26240

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% 23% 10% 27% 4 3 2 2 2 2 7%	5081
	11th to 20th	Day	11% 23% 10% 21% 7% 6% 3 2 3 3 9%	5280
	21st to end	Day	16% 17% 8% 18% 9% 6% 4 2 3 3 13%	5780
February	1st to 10th	Day	16% 20% 6% 15% 9% 5% 3 3 3 3 16%	1890
	11th to 20th	Day	16% 17% 8% 15% 8% 4 4 2 4 4 17%	1843
	21st to end	Day	19% 17% 4 11% 5% 4 4 4 5% 5% 22%	1704
March	1st to 10th	Day	16% 15% 6% 11% 5% 3 3 2 4 6% 29%	5032
	11th to 20th	Day	13% 15% 6% 9% 4 4 3 3 5% 6% 32%	5090
	21st to end	Day	21% 14% 6% 10% 4 4 3 3 4 5% 27%	5586
April	1st to 10th	Day	17% 14% 3 7% 4 4 4 3 5% 6% 32%	2410
	11th to 20th	Day	19% 12% 3 6% 4 3 4 4 5% 5% 35%	2607
	21st to end	Day	20% 10% 2 7% 4 4 4 3 5% 7% 35%	2730
May	1st to 10th	Day	20% 9% 3 7% 5% 5% 4 4 5% 6% 32%	7616
	11th to 20th	Day	19% 8% 3 6% 4 4 4 3 5% 7% 36%	7626
	21st to end	Day	18% 7% 2 6% 4 4 4 4 5% 6% 39%	9036
June	1st to 10th	Day	15% 6% 2 5% 4 4 5% 3 6% 8% 41%	2940
	11th to 20th	Day	13% 6% 3 7% 5% 4 5% 3 6% 9% 40%	2870
	21st to end	Day	13% 5% 2 5% 3 4 4 4 7% 9% 43%	2800
July	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 6% 10% 46%	6325
	11th to 20th	Day	13% 5% 3 5% 4 4 4 4 6% 10% 43%	5900
	21st to end	Day	12% 4 2 5% 4 4 4 4 6% 8% 47%	6424
August	1st to 10th	Day	16% 5% 2 6% 4 4 4 4 7% 9% 40%	4234
	11th to 20th	Day	15% 5% 2 7% 5% 5% 5% 4 7% 9% 36%	4174
	21st to end	Day	12% 5% 2 6% 4 4 5% 4 6% 8% 44%	4526
September	1st to 10th	Day	17% 6% 3 5% 3 4 5% 3 6% 7% 42%	2383
	11th to 20th	Day	12% 5% 2 5% 4 4 4 4 5% 8% 48%	2200
	21st to end	Day	19% 7% 3 7% 5% 5% 4 3 5% 6% 35%	2200
October	1st to 10th	Day	18% 6% 2 7% 4 4 4 4 6% 7% 39%	2015
	11th to 20th	Day	23% 9% 3 7% 5% 5% 4 3 6% 6% 30%	2000
	21st to end	Day	29% 12% 3 7% 5% 4 4 3 5% 6% 23%	2200
November	1st to 10th	Day	18% 15% 4 7% 4 3 3 4 5% 6% 31%	1892
	11th to 20th	Day	18% 23% 4 9% 4 3 4 2 5% 7% 22%	1718
	21st to end	Day	22% 25% 5% 9% 5% 4 4 3 4 6% 13%	1680
December	1st to 10th	Day	18% 34% 11% 10% 5% 4 3 2 3 3 9%	2680
	11th to 20th	Day	21% 27% 8% 13% 4 3 4 2 4 4 11%	3070
	21st to end	Day	24% 25% 6% 15% 5% 4 3 3 3 4 9%	4048
January	1st to 10th	Night	16% 24% 12% 27% 4 3 2 1 2 3 7%	7795
	11th to 20th	Night	10% 23% 11% 21% 8% 6% 4 2 3 4 9%	7680
	21st to end	Night	18% 18% 7% 15% 7% 5% 3 2 4 4 16%	8401
February	1st to 10th	Night	19% 20% 5% 13% 7% 4 4 3 4 4 18%	2730
	11th to 20th	Night	18% 17% 7% 14% 6% 5% 4 3 4 5% 18%	2663
	21st to end	Night	19% 16% 5% 14% 5% 4 4 3 3 5% 21%	2097
March	1st to 10th	Night	20% 16% 4 8% 6% 3 3 3 4 5% 28%	5039
	11th to 20th	Night	14% 16% 4 7% 4 3 4 3 5% 6% 36%	5090
	21st to end	Night	18% 14% 5% 10% 5% 4 3 3 4 4 31%	5588
April	1st to 10th	Night	19% 15% 4 7% 5% 4 4 3 5% 5% 28%	2210
	11th to 20th	Night	20% 10% 2 7% 5% 4 5% 4 6% 6% 31%	1979
	21st to end	Night	15% 11% 3 7% 5% 4 5% 4 5% 6% 34%	1890
May	1st to 10th	Night	24% 9% 3 7% 5% 5% 4 3 5% 6% 30%	5237
	11th to 20th	Night	18% 8% 2 7% 5% 3 5% 3 5% 7% 37%	5234
	21st to end	Night	20% 7% 2 5% 4 4 4 4 6% 8% 37%	5112
June	1st to 10th	Night	11% 6% 2 8% 6% 5% 4 4 6% 9% 41%	1680
	11th to 20th	Night	10% 6% 3 7% 5% 5% 4 4 6% 7% 42%	1640
	21st to end	Night	13% 4 3 6% 5% 5% 4 4 6% 10% 41%	1600
July	1st to 10th	Night	11% 5% 3 6% 4 5% 5% 3 5% 9% 44%	3615
	11th to 20th	Night	13% 5% 2 6% 4 4 5% 4 6% 8% 43%	4057
	21st to end	Night	9% 4 2 6% 4 4 4 4 6% 8% 48%	4427
August	1st to 10th	Night	12% 6% 2 7% 5% 5% 5% 4 7% 7% 40%	2915
	11th to 20th	Night	18% 5% 3 7% 5% 5% 4 3 5% 6% 39%	2875
	21st to end	Night	11% 5% 3 6% 4 4 5% 4 7% 9% 42%	3338
September	1st to 10th	Night	13% 7% 2 5% 3 4 4 4 6% 8% 45%	2014
	11th to 20th	Night	13% 5% 2 5% 3 4 3 3 5% 7% 50%	2200
	21st to end	Night	17% 6% 2 7% 5% 5% 5% 4 5% 7% 36%	2200
October	1st to 10th	Night	18% 7% 3 6% 4 3 3 3 5% 7% 41%	2385
	11th to 20th	Night	24% 9% 2 8% 4 4 4 4 5% 7% 29%	2400
	21st to end	Night	30% 11% 3 6% 4 3 4 3 4 5% 27%	2640
November	1st to 10th	Night	19% 14% 3 8% 5% 4 4 3 4 5% 32%	2624
	11th to 20th	Night	20% 20% 4 9% 4 5% 4 4 4 5% 21%	2899
	21st to end	Night	22% 25% 6% 8% 5% 3 3 3 4 4 18%	2940
December	1st to 10th	Night	16% 31% 11% 9% 5% 4 4 3 3 3 12%	4720
	11th to 20th	Night	19% 28% 8% 12% 4 3 3 3 3 4 13%	5345
	21st to end	Night	22% 23% 6% 13% 5% 4 4 3 4 4 12%	7150

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	85% 4 6% 4 1	5082
	11th to 20th	Day	82% 3 6% 5% 3	5280
	21st to end	Day	77% 4 6% 8% 4	5780
February	1st to 10th	Day	73% 4 7% 11% 5%	1890
	11th to 20th	Day	73% 3 7% 11% 5%	1852
	21st to end	Day	64% 5% 10% 14% 5% 2	1704
March	1st to 10th	Day	58% 6% 12% 20% 5%	5032
	11th to 20th	Day	52% 6% 15% 20% 6% 1	5090
	21st to end	Day	60% 5% 7% 18% 10% 1	5586
April	1st to 10th	Day	53% 6% 12% 17% 12% 1	2410
	11th to 20th	Day	51% 5% 10% 20% 12% 2	2607
	21st to end	Day	50% 5% 10% 20% 11% 3	2730
May	1st to 10th	Day	52% 6% 9% 21% 10% 3	7651
	11th to 20th	Day	47% 7% 10% 23% 11% 1	7630
	21st to end	Day	45% 6% 10% 20% 16% 3	9052
June	1st to 10th	Day	40% 8% 11% 25% 15% 1	2940
	11th to 20th	Day	43% 7% 14% 22% 14% 1	2870
	21st to end	Day	38% 7% 13% 25% 16% 2	2800
July	1st to 10th	Day	35% 6% 14% 26% 18% 2	6255
	11th to 20th	Day	38% 6% 14% 26% 17% 1	5831
	21st to end	Day	36% 6% 13% 26% 19% 1	6240
August	1st to 10th	Day	40% 7% 16% 24% 12%	4221
	11th to 20th	Day	42% 9% 14% 28% 7% 1	4213
	21st to end	Day	37% 7% 14% 29% 13% 1	4526
September	1st to 10th	Day	41% 6% 14% 24% 13% 2	2383
	11th to 20th	Day	36% 7% 14% 28% 16% 1	2200
	21st to end	Day	49% 6% 12% 21% 12% 1	2200
October	1st to 10th	Day	35% 6% 14% 25% 19% 1	3275
	11th to 20th	Day	47% 5% 14% 20% 14% 1	3240
	21st to end	Day	47% 4 14% 26% 8% 1	3538
November	1st to 10th	Day	54% 5% 9% 19% 11% 1	1892
	11th to 20th	Day	63% 6% 9% 13% 7% 2	1718
	21st to end	Day	72% 5% 9% 10% 4	1680
December	1st to 10th	Day	83% 4 7% 5% 1	2680
	11th to 20th	Day	79% 4 6% 9% 1	3066
	21st to end	Day	82% 4 7% 6% 1	4048
January	1st to 10th	Night	86% 3 5% 5% 1	7796
	11th to 20th	Night	80% 4 8% 6% 2	7680
	21st to end	Night	72% 4 8% 12% 4	8401
February	1st to 10th	Night	71% 4 9% 12% 4	2730
	11th to 20th	Night	71% 4 8% 12% 5%	2665
	21st to end	Night	67% 5% 9% 12% 6% 1	2097
March	1st to 10th	Night	59% 5% 12% 16% 9%	5039
	11th to 20th	Night	49% 5% 14% 22% 10% 1	5090
	21st to end	Night	57% 5% 9% 16% 12% 1	5588
April	1st to 10th	Night	58% 5% 9% 16% 10% 2	2210
	11th to 20th	Night	51% 7% 10% 18% 12% 2	1979
	21st to end	Night	49% 6% 10% 21% 11% 3	1890
May	1st to 10th	Night	55% 5% 9% 15% 11% 5%	5264
	11th to 20th	Night	47% 6% 11% 23% 12% 1	5235
	21st to end	Night	45% 5% 12% 22% 15% 1	5119
June	1st to 10th	Night	40% 7% 11% 23% 16% 4	1680
	11th to 20th	Night	39% 6% 13% 21% 19% 2	1640
	21st to end	Night	38% 8% 13% 23% 17% 1	1600
July	1st to 10th	Night	38% 5% 12% 22% 20% 3	3577
	11th to 20th	Night	37% 6% 13% 26% 16% 3	4006
	21st to end	Night	33% 6% 13% 22% 25% 2	4297
August	1st to 10th	Night	40% 8% 12% 26% 13% 1	2904
	11th to 20th	Night	45% 6% 12% 26% 11% 1	2902
	21st to end	Night	36% 7% 14% 28% 13% 1	3338
September	1st to 10th	Night	36% 7% 12% 28% 14% 3	2014
	11th to 20th	Night	33% 6% 13% 27% 20% 1	2200
	21st to end	Night	47% 6% 11% 20% 15% 1	2200
October	1st to 10th	Night	38% 5% 10% 25% 22% 1	3905
	11th to 20th	Night	50% 5% 11% 18% 14% 2	3899
	21st to end	Night	46% 4 14% 21% 14% 2	4252
November	1st to 10th	Night	53% 5% 12% 19% 9% 2	2624
	11th to 20th	Night	64% 6% 8% 13% 6% 2	2899
	21st to end	Night	71% 4 8% 12% 4	2940
December	1st to 10th	Night	78% 4 10% 6% 2	4720
	11th to 20th	Night	76% 4 10% 9% 1	5348
	21st to end	Night	76% 7% 8% 9% 1	7150

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	31% 33% 23% 9% 4	297
	11th to 20th	Day	36% 33% 22% 7% 3	330
	21st to end	Day	31% 31% 30% 7% 2	363
February	1st to 10th	Day	30% 26% 34% 9% 1	330
	11th to 20th	Day	32% 29% 31% 8% 1	330
	21st to end	Day	32% 33% 27% 7%	273
March	1st to 10th	Day	28% 24% 33% 10% 4	527
	11th to 20th	Day	32% 21% 32% 11% 3 1	540
	21st to end	Day	34% 22% 28% 14% 2	594
April	1st to 10th	Day	26% 27% 29% 14% 4	540
	11th to 20th	Day	30% 20% 26% 17% 6% 2	532
	21st to end	Day	27% 17% 33% 17% 5% 1	540
May	1st to 10th	Day	28% 18% 32% 16% 5% 2	543
	11th to 20th	Day	21% 15% 31% 21% 10% 2	567
	21st to end	Day	18% 10% 29% 26% 13% 4	617
June	1st to 10th	Day	17% 12% 36% 24% 9% 2	570
	11th to 20th	Day	18% 11% 29% 27% 12% 2	550
	21st to end	Day	15% 10% 32% 31% 11% 2	530
July	1st to 10th	Day	13% 5% 27% 31% 17% 6%	525
	11th to 20th	Day	15% 7% 26% 31% 15% 6%	524
	21st to end	Day	11% 4 32% 32% 15% 5%	576
August	1st to 10th	Day	11% 7% 27% 31% 18% 6%	526
	11th to 20th	Day	17% 6% 24% 30% 16% 7%	519
	21st to end	Day	13% 9% 25% 30% 17% 5%	583
September	1st to 10th	Day	16% 10% 23% 27% 18% 6%	530
	11th to 20th	Day	10% 5% 24% 32% 22% 8%	530
	21st to end	Day	19% 13% 29% 23% 11% 5%	530
October	1st to 10th	Day	17% 10% 30% 23% 16% 3	530
	11th to 20th	Day	27% 19% 30% 18% 6% 1	530
	21st to end	Day	36% 18% 28% 17% 1	583
November	1st to 10th	Day	31% 21% 26% 14% 7% 1	370
	11th to 20th	Day	41% 22% 24% 10% 3	239
	21st to end	Day	37% 24% 31% 8%	220
December	1st to 10th	Day	34% 29% 28% 7% 2	220
	11th to 20th	Day	30% 34% 26% 10% 1	220
	21st to end	Day	38% 24% 28% 8% 1	242
January	1st to 10th	Night	31% 27% 28% 10% 3	840
	11th to 20th	Night	34% 24% 26% 13% 2	840
	21st to end	Night	29% 23% 30% 15% 2	924
February	1st to 10th	Night	30% 21% 29% 17% 2	840
	11th to 20th	Night	28% 23% 30% 16% 2	823
	21st to end	Night	29% 22% 31% 16% 1	692
March	1st to 10th	Night	27% 19% 29% 21% 3	840
	11th to 20th	Night	25% 20% 31% 19% 5%	840
	21st to end	Night	27% 16% 29% 22% 6% 1	924
April	1st to 10th	Night	28% 16% 29% 22% 5%	840
	11th to 20th	Night	26% 13% 30% 23% 7% 1	735
	21st to end	Night	20% 12% 30% 30% 7%	630
May	1st to 10th	Night	25% 8% 25% 30% 11% 1	630
	11th to 20th	Night	20% 7% 27% 34% 10% 1	621
	21st to end	Night	16% 5% 25% 30% 21% 2	460
June	1st to 10th	Night	13% 5% 30% 35% 16% 2	420
	11th to 20th	Night	13% 7% 25% 37% 17% 1	410
	21st to end	Night	12% 6% 27% 34% 20%	400
July	1st to 10th	Night	9% 5% 19% 42% 21% 5%	394
	11th to 20th	Night	11% 4 23% 34% 25% 3	582
	21st to end	Night	11% 3 20% 38% 25% 3	657
August	1st to 10th	Night	10% 3 18% 40% 24% 5%	597
	11th to 20th	Night	14% 3 16% 33% 29% 5%	594
	21st to end	Night	15% 5% 22% 29% 26% 3	723
September	1st to 10th	Night	16% 7% 19% 30% 23% 5%	800
	11th to 20th	Night	13% 5% 16% 33% 28% 6%	800
	21st to end	Night	20% 10% 22% 26% 17% 4	800
October	1st to 10th	Night	22% 11% 23% 25% 17% 3	800
	11th to 20th	Night	28% 16% 28% 20% 8% 1	800
	21st to end	Night	35% 15% 28% 19% 3	880
November	1st to 10th	Night	28% 15% 27% 21% 8% 1	820
	11th to 20th	Night	34% 20% 27% 14% 5% 1	840
	21st to end	Night	36% 23% 27% 11% 4	840
December	1st to 10th	Night	37% 24% 25% 10% 4	840
	11th to 20th	Night	33% 29% 25% 11% 2	840
	21st to end	Night	32% 23% 30% 13% 1	924

Page generated at 2026-06-13 02:31:38. Version ac07

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