Lorain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lorain 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% 10% 4 8% 5% 4 4 4 5% 7% 33%	105416
	Night	17% 12% 4 9% 5% 4 4 3 5% 6% 30%	103872
Transparency	Day	50% 6% 12% 20% 12% 1	109077
	Night	52% 6% 11% 19% 11% 2	108352
Seeing	Day	20% 14% 28% 22% 12% 4	15262
	Night	22% 11% 27% 27% 12% 2	24830

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	20% 20% 8% 15% 5% 4 3 2 4 5% 14%	2926
	11th to 20th	Day	15% 23% 8% 14% 7% 7% 6% 3 3 4 11%	2930
	21st to end	Day	27% 19% 9% 13% 8% 4 3 2 3 3 9%	3133
February	1st to 10th	Day	17% 17% 5% 11% 6% 4 4 3 4 5% 22%	1710
	11th to 20th	Day	15% 13% 5% 14% 8% 5% 4 3 4 5% 23%	1750
	21st to end	Day	18% 12% 4 11% 6% 4 4 4 6% 6% 25%	1570
March	1st to 10th	Day	23% 13% 5% 8% 4 4 3 3 4 6% 28%	3303
	11th to 20th	Day	13% 13% 5% 8% 5% 4 4 3 5% 5% 35%	3480
	21st to end	Day	20% 12% 5% 9% 5% 4 3 3 4 6% 30%	3815
April	1st to 10th	Day	13% 13% 3 7% 5% 4 5% 4 5% 7% 34%	2117
	11th to 20th	Day	18% 10% 3 6% 4 4 5% 3 5% 5% 37%	2442
	21st to end	Day	19% 10% 3 7% 4 4 4 3 4 7% 35%	2470
May	1st to 10th	Day	19% 8% 3 8% 5% 5% 4 3 5% 6% 33%	4082
	11th to 20th	Day	17% 7% 3 7% 4 4 4 4 5% 7% 38%	4081
	21st to end	Day	11% 5% 2 6% 4 5% 5% 4 7% 9% 43%	4476
June	1st to 10th	Day	13% 5% 2 6% 5% 4 5% 5% 7% 8% 41%	2603
	11th to 20th	Day	10% 5% 2 7% 4 5% 5% 5% 7% 9% 43%	2763
	21st to end	Day	10% 5% 2 5% 4 4 5% 4 7% 10% 43%	2745
July	1st to 10th	Day	9% 5% 2 7% 5% 5% 4 4 6% 10% 43%	4440
	11th to 20th	Day	9% 3 1 5% 5% 4 5% 4 6% 10% 48%	4120
	21st to end	Day	9% 5% 2 6% 5% 5% 5% 4 7% 8% 44%	4466
August	1st to 10th	Day	11% 6% 2 6% 4 4 4 4 6% 8% 43%	4104
	11th to 20th	Day	10% 6% 2 7% 4 5% 5% 5% 7% 9% 41%	4044
	21st to end	Day	9% 5% 2 6% 5% 4 5% 4 6% 11% 42%	4510
September	1st to 10th	Day	14% 5% 2 5% 4 4 5% 4 5% 7% 45%	2134
	11th to 20th	Day	10% 6% 2 6% 4 4 4 4 6% 9% 46%	2090
	21st to end	Day	19% 8% 2 7% 4 4 4 4 5% 6% 38%	2090
October	1st to 10th	Day	14% 7% 3 7% 5% 4 4 4 5% 7% 40%	1990
	11th to 20th	Day	20% 7% 3 7% 5% 4 4 3 5% 6% 36%	1900
	21st to end	Day	21% 12% 3 8% 5% 5% 4 4 5% 8% 27%	2040
November	1st to 10th	Day	14% 11% 3 8% 5% 4 5% 3 5% 7% 36%	1762
	11th to 20th	Day	18% 19% 4 7% 5% 4 3 2 5% 6% 27%	1800
	21st to end	Day	19% 18% 7% 9% 5% 5% 4 3 5% 7% 18%	1635
December	1st to 10th	Day	17% 18% 8% 14% 6% 4 4 3 5% 6% 15%	2600
	11th to 20th	Day	21% 20% 7% 12% 7% 4 4 3 5% 5% 13%	2990
	21st to end	Day	24% 22% 7% 12% 6% 4 4 3 4 3 11%	4305
January	1st to 10th	Night	18% 22% 9% 13% 6% 4 3 2 3 4 15%	4239
	11th to 20th	Night	14% 21% 9% 17% 7% 5% 6% 4 4 3 10%	4250
	21st to end	Night	28% 19% 8% 12% 4 3 3 2 3 3 14%	4546
February	1st to 10th	Night	20% 14% 5% 12% 6% 4 4 3 4 5% 22%	2470
	11th to 20th	Night	18% 16% 5% 11% 6% 4 4 3 5% 5% 23%	2314
	21st to end	Night	22% 13% 5% 11% 5% 4 4 3 5% 5% 24%	1884
March	1st to 10th	Night	22% 14% 4 6% 4 3 3 2 4 5% 33%	3549
	11th to 20th	Night	15% 11% 4 6% 4 5% 5% 4 5% 6% 36%	3480
	21st to end	Night	18% 10% 5% 8% 4 4 4 3 5% 5% 34%	3817
April	1st to 10th	Night	16% 15% 2 6% 5% 4 4 4 5% 6% 33%	2079
	11th to 20th	Night	16% 10% 3 8% 5% 4 5% 4 7% 7% 33%	1687
	21st to end	Night	16% 9% 2 6% 6% 4 4 4 6% 6% 37%	1710
May	1st to 10th	Night	21% 8% 3 8% 5% 4 4 4 6% 7% 29%	2813
	11th to 20th	Night	17% 7% 3 7% 5% 3 5% 4 5% 7% 37%	2812
	21st to end	Night	11% 4 2 5% 4 5% 5% 4 6% 8% 47%	3079
June	1st to 10th	Night	12% 6% 3 6% 5% 4 5% 4 6% 6% 43%	1572
	11th to 20th	Night	10% 4 2 7% 5% 5% 5% 5% 7% 8% 42%	1410
	21st to end	Night	11% 5% 2 5% 5% 5% 4 4 6% 10% 42%	1426
July	1st to 10th	Night	10% 4 2 5% 4 5% 5% 4 6% 10% 46%	2530
	11th to 20th	Night	9% 3 2 6% 4 4 5% 4 6% 8% 49%	2835
	21st to end	Night	6% 5% 2 6% 5% 5% 5% 5% 7% 9% 45%	3087
August	1st to 10th	Night	12% 6% 3 7% 5% 4 4 4 6% 8% 42%	2825
	11th to 20th	Night	12% 7% 2 7% 4 4 4 3 5% 7% 44%	2785
	21st to end	Night	9% 5% 2 7% 4 6% 6% 4 6% 6% 46%	3124
September	1st to 10th	Night	11% 6% 3 5% 5% 4 5% 4 6% 7% 45%	2032
	11th to 20th	Night	11% 5% 2 5% 5% 4 4 3 5% 7% 50%	2090
	21st to end	Night	16% 7% 2 8% 4 5% 5% 3 5% 6% 39%	2090
October	1st to 10th	Night	15% 6% 2 6% 4 4 4 3 5% 7% 43%	2190
	11th to 20th	Night	22% 8% 2 7% 5% 4 4 3 5% 6% 34%	2280
	21st to end	Night	26% 10% 3 7% 5% 5% 4 3 5% 5% 28%	2555
November	1st to 10th	Night	16% 13% 3 7% 5% 4 4 3 5% 6% 35%	2536
	11th to 20th	Night	18% 17% 4 9% 5% 4 4 3 4 5% 25%	2600
	21st to end	Night	24% 17% 5% 7% 5% 4 4 3 5% 5% 21%	2761
December	1st to 10th	Night	17% 17% 8% 11% 6% 5% 5% 4 5% 7% 15%	4580
	11th to 20th	Night	19% 21% 7% 10% 5% 3 4 3 4 5% 17%	5205
	21st to end	Night	25% 19% 6% 12% 5% 4 4 3 5% 5% 12%	6630

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	75% 5% 9% 9% 2	2927
	11th to 20th	Day	78% 4 9% 7% 3	2930
	21st to end	Day	83% 3 6% 5% 3	3133
February	1st to 10th	Day	65% 4 11% 13% 6%	1710
	11th to 20th	Day	65% 4 10% 15% 6% 1	1759
	21st to end	Day	60% 5% 14% 13% 7% 1	1570
March	1st to 10th	Day	60% 4 9% 21% 5%	3303
	11th to 20th	Day	51% 5% 17% 20% 7% 1	3480
	21st to end	Day	57% 4 14% 15% 10% 1	3815
April	1st to 10th	Day	51% 5% 12% 18% 13% 1	2117
	11th to 20th	Day	50% 3 13% 17% 14% 2	2442
	21st to end	Day	50% 4 12% 21% 11% 2	2470
May	1st to 10th	Day	51% 6% 10% 21% 11% 1	4120
	11th to 20th	Day	45% 7% 13% 24% 9% 1	4085
	21st to end	Day	37% 7% 13% 20% 16% 6%	4489
June	1st to 10th	Day	41% 6% 11% 27% 13% 1	2603
	11th to 20th	Day	38% 7% 15% 23% 15% 2	2763
	21st to end	Day	36% 6% 14% 23% 17% 3	2745
July	1st to 10th	Day	38% 6% 12% 23% 18% 3	4371
	11th to 20th	Day	30% 7% 13% 29% 19% 2	4051
	21st to end	Day	37% 7% 15% 19% 19% 2	4324
August	1st to 10th	Day	38% 7% 15% 25% 14%	4091
	11th to 20th	Day	37% 7% 13% 32% 10% 1	4083
	21st to end	Day	35% 7% 16% 27% 13% 2	4510
September	1st to 10th	Day	38% 7% 14% 20% 17% 3	2134
	11th to 20th	Day	37% 6% 13% 25% 18% 1	2090
	21st to end	Day	45% 5% 11% 21% 17%	2090
October	1st to 10th	Day	32% 6% 14% 30% 18% 1	3302
	11th to 20th	Day	45% 5% 10% 20% 19% 1	3140
	21st to end	Day	43% 4 12% 23% 17%	3342
November	1st to 10th	Day	47% 5% 11% 23% 14% 1	1762
	11th to 20th	Day	57% 5% 9% 17% 10% 1	1800
	21st to end	Day	64% 7% 10% 14% 6%	1635
December	1st to 10th	Day	66% 7% 13% 12% 3	2600
	11th to 20th	Day	70% 5% 9% 13% 3	2986
	21st to end	Day	78% 5% 6% 8% 3	4305
January	1st to 10th	Night	71% 7% 7% 11% 4	4239
	11th to 20th	Night	78% 5% 8% 7% 2	4250
	21st to end	Night	76% 4 8% 8% 3	4546
February	1st to 10th	Night	64% 6% 11% 14% 5%	2470
	11th to 20th	Night	63% 5% 9% 16% 7%	2316
	21st to end	Night	63% 4 10% 14% 7% 1	1884
March	1st to 10th	Night	55% 4 12% 21% 8%	3549
	11th to 20th	Night	45% 7% 17% 18% 11% 1	3480
	21st to end	Night	50% 7% 11% 22% 10% 1	3817
April	1st to 10th	Night	52% 5% 12% 16% 13% 3	2079
	11th to 20th	Night	48% 5% 12% 17% 16% 3	1687
	21st to end	Night	46% 5% 11% 20% 14% 3	1710
May	1st to 10th	Night	54% 5% 10% 18% 10% 2	2840
	11th to 20th	Night	44% 9% 10% 22% 13% 2	2813
	21st to end	Night	32% 7% 12% 26% 20% 3	3087
June	1st to 10th	Night	39% 6% 10% 26% 15% 3	1572
	11th to 20th	Night	37% 8% 13% 21% 18% 3	1410
	21st to end	Night	36% 7% 12% 25% 17% 2	1426
July	1st to 10th	Night	33% 7% 12% 25% 18% 6%	2490
	11th to 20th	Night	30% 8% 13% 27% 18% 4	2782
	21st to end	Night	33% 7% 16% 21% 21% 3	2988
August	1st to 10th	Night	39% 8% 12% 25% 15% 2	2814
	11th to 20th	Night	36% 7% 11% 31% 14% 1	2812
	21st to end	Night	36% 7% 12% 27% 15% 3	3124
September	1st to 10th	Night	36% 6% 12% 25% 16% 4	2032
	11th to 20th	Night	32% 7% 10% 26% 22% 2	2090
	21st to end	Night	44% 6% 10% 20% 18% 1	2090
October	1st to 10th	Night	30% 5% 9% 30% 25% 1	3658
	11th to 20th	Night	46% 5% 9% 21% 19% 1	3779
	21st to end	Night	42% 5% 9% 25% 17% 2	4203
November	1st to 10th	Night	47% 6% 11% 21% 13% 2	2536
	11th to 20th	Night	57% 6% 9% 17% 9% 2	2600
	21st to end	Night	64% 6% 10% 15% 5%	2761
December	1st to 10th	Night	63% 7% 12% 14% 4	4580
	11th to 20th	Night	68% 5% 10% 14% 3	5208
	21st to end	Night	73% 7% 10% 10% 2	6630

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	28% 23% 33% 10% 5% 1	300
	11th to 20th	Day	29% 27% 34% 7% 3	300
	21st to end	Day	30% 24% 32% 12% 2 1	300
February	1st to 10th	Day	33% 21% 34% 11% 1	270
	11th to 20th	Day	31% 27% 33% 8% 2	270
	21st to end	Day	31% 32% 30% 7% 1	225
March	1st to 10th	Day	27% 22% 32% 14% 5%	375
	11th to 20th	Day	26% 22% 31% 16% 5% 1	460
	21st to end	Day	32% 18% 28% 17% 4 1	506
April	1st to 10th	Day	22% 19% 32% 20% 6% 1	460
	11th to 20th	Day	28% 20% 26% 15% 7% 4	452
	21st to end	Day	29% 14% 32% 17% 6% 2	460
May	1st to 10th	Day	27% 13% 29% 22% 6% 3	463
	11th to 20th	Day	19% 10% 33% 21% 11% 5%	487
	21st to end	Day	14% 9% 25% 29% 16% 6%	529
June	1st to 10th	Day	14% 7% 32% 31% 12% 4	490
	11th to 20th	Day	13% 7% 28% 32% 16% 3	593
	21st to end	Day	12% 9% 30% 30% 17% 2	680
July	1st to 10th	Day	11% 4 24% 29% 23% 9%	671
	11th to 20th	Day	13% 5% 25% 28% 19% 9%	484
	21st to end	Day	10% 6% 23% 32% 21% 8%	532
August	1st to 10th	Day	11% 5% 21% 32% 22% 10%	486
	11th to 20th	Day	13% 5% 21% 33% 19% 9%	479
	21st to end	Day	12% 5% 22% 27% 24% 10%	539
September	1st to 10th	Day	15% 8% 21% 26% 19% 11%	490
	11th to 20th	Day	12% 5% 18% 27% 27% 12%	490
	21st to end	Day	20% 12% 25% 24% 12% 8%	490
October	1st to 10th	Day	14% 10% 27% 24% 19% 6%	490
	11th to 20th	Day	20% 17% 31% 22% 7% 3	490
	21st to end	Day	27% 19% 31% 18% 4 1	489
November	1st to 10th	Day	19% 22% 32% 18% 7% 2	300
	11th to 20th	Day	31% 21% 29% 15% 4 1	300
	21st to end	Day	31% 24% 35% 10% 1	217
December	1st to 10th	Day	24% 31% 25% 16% 4 1	200
	11th to 20th	Day	25% 28% 34% 12% 1	200
	21st to end	Day	31% 21% 33% 12% 2	295
January	1st to 10th	Night	30% 18% 31% 17% 4	800
	11th to 20th	Night	31% 18% 31% 15% 4	800
	21st to end	Night	27% 15% 32% 21% 4	841
February	1st to 10th	Night	29% 14% 32% 20% 4	760
	11th to 20th	Night	25% 17% 33% 22% 3	743
	21st to end	Night	31% 14% 34% 18% 3	628
March	1st to 10th	Night	25% 14% 31% 24% 6%	760
	11th to 20th	Night	22% 15% 32% 24% 7% 1	760
	21st to end	Night	25% 9% 30% 25% 10%	836
April	1st to 10th	Night	23% 14% 31% 27% 5%	758
	11th to 20th	Night	22% 10% 32% 24% 10% 2	563
	21st to end	Night	21% 9% 31% 31% 8% 1	570
May	1st to 10th	Night	22% 8% 25% 34% 11% 1	570
	11th to 20th	Night	22% 6% 25% 30% 16% 2	561
	21st to end	Night	12% 4 23% 34% 23% 4	617
June	1st to 10th	Night	13% 4 28% 37% 16% 1	432
	11th to 20th	Night	10% 3 26% 43% 17% 1	380
	21st to end	Night	12% 4 26% 37% 20% 1	476
July	1st to 10th	Night	11% 2 16% 39% 30% 3	555
	11th to 20th	Night	10% 5% 20% 34% 27% 4	552
	21st to end	Night	10% 1 16% 42% 29% 2	624
August	1st to 10th	Night	9% 4 14% 42% 25% 6%	567
	11th to 20th	Night	11% 4 15% 38% 26% 5%	564
	21st to end	Night	11% 4 17% 34% 29% 5%	627
September	1st to 10th	Night	13% 6% 15% 37% 25% 5%	750
	11th to 20th	Night	13% 3 15% 34% 31% 4	760
	21st to end	Night	18% 9% 21% 29% 19% 4	760
October	1st to 10th	Night	18% 7% 24% 28% 20% 3	760
	11th to 20th	Night	25% 11% 30% 23% 10% 1	760
	21st to end	Night	30% 16% 26% 22% 6%	836
November	1st to 10th	Night	23% 14% 28% 23% 10% 1	780
	11th to 20th	Night	28% 16% 31% 18% 6% 1	800
	21st to end	Night	33% 15% 30% 17% 6%	800
December	1st to 10th	Night	31% 19% 28% 18% 4 1	800
	11th to 20th	Night	28% 18% 32% 18% 3	800
	21st to end	Night	32% 15% 31% 19% 3	880

Page generated at 2025-01-19 03:06:43. Version ac07

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