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 2025-02-21.

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	16% 12% 4 9% 5% 4 4 3 5% 6% 30%	108699
	Night	17% 15% 5% 10% 5% 4 4 3 4 6% 27%	109876
Transparency	Day	53% 6% 11% 19% 10% 1	112344
	Night	58% 5% 10% 16% 9% 1	114370
Seeing	Day	22% 16% 29% 21% 9% 3	14829
	Night	24% 15% 26% 23% 10% 1	24594

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	16% 24% 11% 26% 4 3 2 2 2 2 8%	3919
	11th to 20th	Day	12% 24% 11% 20% 7% 5% 3 2 3 3 10%	4060
	21st to end	Day	20% 19% 8% 17% 7% 5% 4 2 3 3 11%	4466
February	1st to 10th	Day	17% 20% 6% 15% 9% 4 3 2 3 4 16%	1800
	11th to 20th	Day	17% 18% 8% 14% 8% 4 4 2 4 4 16%	1753
	21st to end	Day	20% 16% 4 11% 5% 4 4 4 5% 5% 22%	1546
March	1st to 10th	Day	19% 15% 5% 8% 4 4 3 3 5% 6% 27%	3423
	11th to 20th	Day	12% 19% 6% 8% 4 4 3 3 5% 5% 31%	3480
	21st to end	Day	20% 13% 5% 11% 4 4 3 3 4 5% 29%	3815
April	1st to 10th	Day	17% 14% 3 7% 4 4 4 3 5% 6% 33%	2180
	11th to 20th	Day	19% 12% 3 6% 4 3 4 4 5% 5% 35%	2356
	21st to end	Day	21% 9% 2 7% 4 4 4 3 4 7% 35%	2470
May	1st to 10th	Day	19% 9% 3 7% 5% 5% 4 4 5% 7% 33%	4082
	11th to 20th	Day	18% 10% 3 6% 4 5% 4 3 5% 6% 35%	4081
	21st to end	Day	11% 6% 2 6% 4 4 4 4 6% 8% 44%	4814
June	1st to 10th	Day	15% 6% 2 5% 4 4 5% 4 7% 9% 39%	2660
	11th to 20th	Day	12% 6% 3 7% 5% 5% 4 3 6% 9% 41%	2660
	21st to end	Day	13% 5% 2 5% 3 4 4 4 7% 9% 43%	2660
July	1st to 10th	Day	9% 4 2 5% 4 4 5% 5% 6% 10% 45%	4419
	11th to 20th	Day	12% 4 2 5% 3 4 3 3 6% 10% 46%	4120
	21st to end	Day	10% 4 2 5% 5% 4 5% 4 7% 8% 45%	4466
August	1st to 10th	Day	16% 5% 2 6% 4 4 4 4 7% 9% 39%	4104
	11th to 20th	Day	15% 5% 2 7% 5% 5% 5% 4 7% 9% 35%	4044
	21st to end	Day	12% 5% 2 6% 4 4 5% 4 6% 8% 44%	4387
September	1st to 10th	Day	17% 6% 2 5% 3 4 5% 3 6% 7% 41%	2264
	11th to 20th	Day	12% 6% 2 5% 4 4 4 4 5% 9% 46%	2090
	21st to end	Day	20% 7% 3 7% 5% 5% 4 3 5% 6% 35%	2090
October	1st to 10th	Day	18% 6% 2 7% 4 4 4 4 6% 7% 37%	1914
	11th to 20th	Day	24% 9% 3 7% 5% 5% 4 3 6% 6% 29%	1900
	21st to end	Day	29% 12% 3 7% 4 4 4 3 5% 6% 22%	2090
November	1st to 10th	Day	17% 15% 4 7% 5% 3 4 4 5% 6% 31%	1800
	11th to 20th	Day	17% 22% 4 9% 4 3 4 2 5% 7% 22%	1636
	21st to end	Day	22% 25% 5% 9% 5% 4 4 3 4 6% 13%	1600
December	1st to 10th	Day	18% 34% 11% 10% 5% 4 3 2 3 3 8%	2600
	11th to 20th	Day	22% 27% 8% 13% 3 3 4 2 4 4 11%	2990
	21st to end	Day	24% 25% 6% 15% 5% 4 3 3 3 3 10%	3960
January	1st to 10th	Night	15% 25% 12% 25% 4 3 2 1 2 3 7%	6009
	11th to 20th	Night	10% 25% 11% 19% 8% 5% 4 2 3 4 8%	5900
	21st to end	Night	22% 21% 8% 15% 4 4 2 2 4 4 14%	6490
February	1st to 10th	Night	19% 20% 5% 14% 7% 4 4 3 4 4 17%	2600
	11th to 20th	Night	18% 17% 7% 14% 6% 5% 5% 3 3 5% 18%	2533
	21st to end	Night	20% 16% 5% 14% 5% 4 4 3 3 5% 22%	1904
March	1st to 10th	Night	22% 16% 4 7% 5% 3 3 3 4 5% 30%	3428
	11th to 20th	Night	17% 19% 5% 7% 3 3 3 3 4 5% 31%	3480
	21st to end	Night	18% 13% 4 10% 4 3 3 3 4 4 34%	3817
April	1st to 10th	Night	19% 15% 4 6% 5% 4 4 3 5% 5% 30%	2000
	11th to 20th	Night	20% 9% 2 7% 5% 3 5% 4 6% 6% 32%	1789
	21st to end	Night	16% 11% 3 6% 5% 4 5% 5% 5% 6% 33%	1710
May	1st to 10th	Night	24% 9% 3 6% 5% 4 4 3 5% 7% 32%	2813
	11th to 20th	Night	16% 9% 3 8% 5% 4 5% 3 5% 7% 36%	2812
	21st to end	Night	12% 4 2 4 3 3 4 3 7% 10% 45%	2736
June	1st to 10th	Night	11% 6% 2 8% 6% 5% 5% 4 6% 9% 40%	1520
	11th to 20th	Night	10% 6% 3 8% 5% 5% 4 4 6% 7% 43%	1520
	21st to end	Night	13% 5% 3 6% 5% 5% 4 4 6% 10% 40%	1520
July	1st to 10th	Night	12% 6% 2 6% 4 4 4 3 5% 9% 44%	2537
	11th to 20th	Night	12% 5% 2 6% 4 4 4 4 6% 9% 46%	2840
	21st to end	Night	9% 4 2 6% 5% 5% 5% 5% 7% 8% 45%	3087
August	1st to 10th	Night	12% 6% 3 8% 5% 5% 5% 4 7% 7% 39%	2825
	11th to 20th	Night	18% 6% 3 7% 5% 5% 4 3 5% 6% 38%	2785
	21st to end	Night	11% 5% 3 6% 4 4 5% 4 7% 8% 42%	3236
September	1st to 10th	Night	14% 8% 2 5% 3 3 4 4 6% 8% 44%	1913
	11th to 20th	Night	13% 5% 2 5% 4 4 3 3 6% 7% 48%	2090
	21st to end	Night	17% 7% 2 7% 5% 5% 5% 4 5% 7% 35%	2090
October	1st to 10th	Night	19% 7% 3 6% 4 3 3 3 5% 7% 39%	2266
	11th to 20th	Night	24% 9% 2 8% 5% 4 4 4 5% 7% 28%	2280
	21st to end	Night	29% 11% 3 6% 4 3 4 3 4 5% 26%	2508
November	1st to 10th	Night	19% 14% 3 8% 5% 4 4 3 4 5% 31%	2496
	11th to 20th	Night	20% 20% 4 9% 4 5% 4 4 4 5% 21%	2761
	21st to end	Night	22% 25% 6% 7% 5% 3 3 3 4 4 18%	2800
December	1st to 10th	Night	16% 32% 11% 9% 5% 4 4 3 3 3 11%	4580
	11th to 20th	Night	19% 29% 8% 11% 4 3 3 3 3 4 13%	5205
	21st to end	Night	22% 24% 6% 13% 5% 4 4 3 4 5% 12%	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	84% 5% 5% 5% 1	3920
	11th to 20th	Day	82% 2 8% 6% 2	4060
	21st to end	Day	78% 4 7% 8% 3	4466
February	1st to 10th	Day	74% 4 7% 10% 5%	1800
	11th to 20th	Day	74% 3 7% 11% 5%	1762
	21st to end	Day	63% 6% 10% 14% 5% 2	1546
March	1st to 10th	Day	57% 7% 9% 23% 4	3423
	11th to 20th	Day	54% 7% 16% 16% 5% 1	3480
	21st to end	Day	57% 6% 8% 17% 10% 1	3815
April	1st to 10th	Day	52% 6% 12% 17% 13% 1	2180
	11th to 20th	Day	51% 5% 10% 20% 12% 2	2356
	21st to end	Day	52% 5% 10% 19% 11% 3	2470
May	1st to 10th	Day	51% 7% 8% 23% 10% 1	4120
	11th to 20th	Day	49% 7% 11% 22% 9% 2	4085
	21st to end	Day	38% 9% 12% 22% 15% 4	4828
June	1st to 10th	Day	41% 8% 12% 24% 13% 1	2660
	11th to 20th	Day	41% 7% 14% 23% 14% 1	2660
	21st to end	Day	38% 7% 13% 25% 15% 2	2660
July	1st to 10th	Day	35% 6% 15% 25% 17% 3	4349
	11th to 20th	Day	34% 6% 13% 28% 18% 1	4051
	21st to end	Day	37% 7% 15% 23% 17% 1	4324
August	1st to 10th	Day	41% 7% 15% 24% 12%	4091
	11th to 20th	Day	42% 9% 14% 28% 6% 1	4083
	21st to end	Day	37% 6% 14% 28% 14% 1	4387
September	1st to 10th	Day	42% 6% 14% 22% 13% 2	2264
	11th to 20th	Day	37% 7% 14% 25% 16% 1	2090
	21st to end	Day	50% 5% 12% 21% 12% 1	2090
October	1st to 10th	Day	36% 6% 14% 25% 18% 1	3174
	11th to 20th	Day	47% 5% 14% 19% 13% 1	3140
	21st to end	Day	47% 4 14% 27% 8%	3428
November	1st to 10th	Day	54% 5% 10% 19% 11% 1	1800
	11th to 20th	Day	63% 6% 9% 13% 7% 2	1636
	21st to end	Day	72% 5% 9% 10% 4	1600
December	1st to 10th	Day	83% 4 7% 5% 1	2600
	11th to 20th	Day	79% 4 6% 9% 1	2986
	21st to end	Day	82% 4 7% 6% 1	3960
January	1st to 10th	Night	85% 3 5% 5% 2	6009
	11th to 20th	Night	80% 4 8% 6% 1	5900
	21st to end	Night	76% 4 7% 8% 4	6490
February	1st to 10th	Night	72% 4 9% 12% 3	2600
	11th to 20th	Night	70% 4 8% 13% 5%	2535
	21st to end	Night	67% 5% 9% 12% 7% 1	1904
March	1st to 10th	Night	58% 5% 11% 18% 8%	3428
	11th to 20th	Night	55% 5% 15% 17% 8% 1	3480
	21st to end	Night	53% 5% 10% 18% 13% 1	3817
April	1st to 10th	Night	56% 5% 9% 17% 11% 2	2000
	11th to 20th	Night	50% 7% 10% 18% 12% 3	1789
	21st to end	Night	49% 6% 10% 20% 11% 3	1710
May	1st to 10th	Night	53% 5% 9% 18% 11% 4	2840
	11th to 20th	Night	46% 7% 12% 23% 11% 2	2813
	21st to end	Night	32% 7% 14% 27% 17% 3	2743
June	1st to 10th	Night	40% 7% 11% 24% 15% 2	1520
	11th to 20th	Night	38% 6% 13% 21% 19% 3	1520
	21st to end	Night	39% 8% 12% 23% 16% 1	1520
July	1st to 10th	Night	38% 6% 11% 22% 19% 4	2497
	11th to 20th	Night	34% 6% 12% 28% 16% 4	2786
	21st to end	Night	35% 7% 14% 22% 21% 1	2988
August	1st to 10th	Night	41% 8% 11% 27% 12% 1	2814
	11th to 20th	Night	46% 6% 12% 26% 10% 1	2812
	21st to end	Night	36% 7% 14% 28% 14% 2	3236
September	1st to 10th	Night	37% 7% 12% 27% 14% 3	1913
	11th to 20th	Night	34% 6% 13% 25% 20% 1	2090
	21st to end	Night	48% 6% 11% 21% 14% 1	2090
October	1st to 10th	Night	38% 5% 10% 24% 21% 1	3786
	11th to 20th	Night	50% 5% 11% 18% 14% 2	3779
	21st to end	Night	46% 4 14% 21% 14% 1	4120
November	1st to 10th	Night	53% 5% 12% 18% 9% 2	2496
	11th to 20th	Night	65% 6% 8% 13% 6% 3	2761
	21st to end	Night	71% 4 9% 12% 4	2800
December	1st to 10th	Night	79% 4 10% 6% 1	4580
	11th to 20th	Night	76% 4 10% 8% 1	5208
	21st to end	Night	76% 7% 8% 9% 1	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	29% 34% 24% 10% 4	270
	11th to 20th	Day	33% 33% 23% 7% 3	300
	21st to end	Day	29% 31% 31% 7% 2	330
February	1st to 10th	Day	32% 26% 33% 8%	300
	11th to 20th	Day	32% 28% 31% 8% 1	300
	21st to end	Day	34% 30% 28% 8%	225
March	1st to 10th	Day	28% 23% 34% 11% 4	448
	11th to 20th	Day	28% 20% 35% 12% 4 1	460
	21st to end	Day	33% 21% 27% 16% 3	506
April	1st to 10th	Day	23% 28% 29% 15% 5%	460
	11th to 20th	Day	29% 19% 27% 17% 6% 2	452
	21st to end	Day	26% 18% 33% 17% 5% 1	460
May	1st to 10th	Day	28% 16% 31% 18% 5% 2	463
	11th to 20th	Day	20% 14% 30% 23% 11% 2	487
	21st to end	Day	15% 8% 29% 29% 15% 5%	529
June	1st to 10th	Day	17% 10% 36% 25% 10% 2	490
	11th to 20th	Day	15% 11% 30% 29% 13% 2	490
	21st to end	Day	15% 10% 32% 30% 11% 2	490
July	1st to 10th	Day	13% 5% 27% 30% 18% 7%	485
	11th to 20th	Day	14% 6% 26% 32% 16% 6%	484
	21st to end	Day	10% 4 33% 32% 15% 5%	532
August	1st to 10th	Day	12% 7% 26% 30% 18% 7%	486
	11th to 20th	Day	16% 6% 24% 30% 17% 7%	479
	21st to end	Day	13% 8% 24% 31% 18% 6%	539
September	1st to 10th	Day	16% 9% 23% 28% 17% 7%	490
	11th to 20th	Day	10% 6% 24% 31% 21% 8%	490
	21st to end	Day	19% 13% 29% 22% 11% 5%	490
October	1st to 10th	Day	18% 11% 30% 22% 16% 3	490
	11th to 20th	Day	28% 18% 30% 18% 6% 1	490
	21st to end	Day	36% 18% 27% 17% 1	539
November	1st to 10th	Day	29% 22% 26% 14% 8% 1	338
	11th to 20th	Day	38% 23% 26% 10% 3	217
	21st to end	Day	36% 25% 32% 9%	200
December	1st to 10th	Day	33% 31% 27% 8% 2 1	200
	11th to 20th	Day	28% 34% 27% 10% 1	200
	21st to end	Day	35% 25% 30% 8% 1	220
January	1st to 10th	Night	31% 27% 29% 10% 4	800
	11th to 20th	Night	34% 23% 27% 14% 2	800
	21st to end	Night	29% 23% 31% 15% 2	880
February	1st to 10th	Night	31% 22% 29% 16% 2	800
	11th to 20th	Night	27% 23% 30% 16% 2	783
	21st to end	Night	29% 22% 31% 17% 1	629
March	1st to 10th	Night	26% 19% 29% 22% 4	760
	11th to 20th	Night	24% 20% 31% 19% 5% 1	760
	21st to end	Night	26% 15% 28% 24% 6% 1	836
April	1st to 10th	Night	25% 16% 29% 24% 5%	760
	11th to 20th	Night	25% 12% 31% 23% 8% 1	665
	21st to end	Night	20% 12% 30% 30% 7% 1	570
May	1st to 10th	Night	24% 8% 24% 31% 12% 1	570
	11th to 20th	Night	20% 6% 26% 36% 11% 1	561
	21st to end	Night	13% 6% 24% 32% 23% 3	416
June	1st to 10th	Night	13% 4 30% 35% 16% 2	380
	11th to 20th	Night	13% 6% 24% 39% 18% 1	380
	21st to end	Night	13% 6% 27% 34% 20%	380
July	1st to 10th	Night	10% 5% 19% 40% 22% 5%	374
	11th to 20th	Night	11% 4 23% 33% 26% 3	552
	21st to end	Night	11% 3 21% 37% 26% 3	624
August	1st to 10th	Night	11% 3 17% 40% 24% 5%	567
	11th to 20th	Night	14% 2 17% 32% 29% 5%	564
	21st to end	Night	15% 5% 22% 29% 26% 3	687
September	1st to 10th	Night	16% 7% 18% 29% 24% 5%	760
	11th to 20th	Night	14% 5% 17% 33% 26% 5%	760
	21st to end	Night	20% 11% 22% 26% 17% 4	760
October	1st to 10th	Night	23% 11% 23% 24% 17% 3	760
	11th to 20th	Night	29% 16% 27% 20% 8% 1	760
	21st to end	Night	35% 15% 27% 19% 3	836
November	1st to 10th	Night	27% 16% 27% 22% 8% 1	780
	11th to 20th	Night	34% 20% 27% 14% 5% 1	800
	21st to end	Night	36% 22% 27% 12% 4	800
December	1st to 10th	Night	37% 25% 25% 10% 4	800
	11th to 20th	Night	33% 28% 26% 12% 2	800
	21st to end	Night	32% 23% 30% 13% 1	880

Page generated at 2025-02-18 03:26:33. Version ac07

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