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 2026-05-17.

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 9% 5% 4 4 3 5% 7% 33%	132323
	Night	16% 12% 4 10% 5% 4 4 3 5% 6% 30%	130489
Transparency	Day	50% 6% 12% 20% 11% 1	135940
	Night	52% 6% 11% 19% 11% 1	134944
Seeing	Day	20% 14% 28% 22% 12% 4	17008
	Night	22% 11% 27% 26% 12% 2	26548

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	17% 19% 7% 23% 5% 4 3 2 4 4 12%	5258
	11th to 20th	Day	13% 20% 7% 18% 9% 6% 5% 3 3 4 13%	5280
	21st to end	Day	19% 17% 7% 13% 8% 6% 5% 3 4 4 13%	5780
February	1st to 10th	Day	17% 17% 5% 12% 6% 4 4 3 4 5% 22%	1890
	11th to 20th	Day	15% 13% 6% 14% 8% 5% 4 3 4 5% 23%	1940
	21st to end	Day	18% 12% 5% 12% 6% 4 4 4 6% 6% 24%	1730
March	1st to 10th	Day	18% 12% 6% 10% 5% 4 3 3 4 6% 30%	4853
	11th to 20th	Day	12% 12% 4 8% 5% 4 4 4 5% 5% 37%	5090
	21st to end	Day	18% 12% 5% 9% 5% 4 4 3 4 6% 29%	5586
April	1st to 10th	Day	15% 12% 3 7% 5% 4 5% 4 5% 7% 33%	2340
	11th to 20th	Day	17% 10% 3 7% 4 4 5% 3 5% 5% 36%	2702
	21st to end	Day	18% 10% 3 7% 4 4 5% 3 4 7% 36%	2730
May	1st to 10th	Day	21% 9% 3 8% 5% 4 4 3 5% 5% 32%	5992
	11th to 20th	Day	16% 8% 3 7% 5% 5% 4 4 5% 7% 36%	5939
	21st to end	Day	17% 7% 2 6% 4 4 4 4 6% 8% 38%	6433
June	1st to 10th	Day	13% 6% 2 6% 5% 4 4 5% 7% 7% 41%	2740
	11th to 20th	Day	11% 5% 2 7% 4 5% 5% 5% 6% 9% 42%	2909
	21st to end	Day	10% 4 2 5% 4 4 5% 4 7% 10% 44%	2889
July	1st to 10th	Day	9% 5% 2 6% 4 4 4 4 6% 10% 46%	6360
	11th to 20th	Day	9% 4 2 6% 5% 4 5% 4 7% 10% 44%	5900
	21st to end	Day	11% 5% 2 6% 4 5% 4 4 6% 8% 45%	6424
August	1st to 10th	Day	11% 6% 2 6% 4 4 4 4 6% 8% 44%	4234
	11th to 20th	Day	10% 5% 2 7% 4 5% 5% 4 7% 9% 41%	4174
	21st to end	Day	9% 5% 2 6% 5% 4 5% 4 6% 11% 43%	4652
September	1st to 10th	Day	14% 5% 2 5% 4 4 5% 4 5% 7% 46%	2246
	11th to 20th	Day	10% 6% 2 6% 4 4 4 4 5% 9% 47%	2200
	21st to end	Day	18% 8% 2 7% 4 4 4 4 5% 6% 39%	2200
October	1st to 10th	Day	14% 7% 3 6% 4 4 4 3 5% 7% 41%	2095
	11th to 20th	Day	19% 7% 3 7% 5% 4 4 3 5% 6% 37%	2000
	21st to end	Day	21% 11% 3 8% 5% 4 4 3 5% 8% 27%	2147
November	1st to 10th	Day	15% 11% 3 8% 5% 4 5% 3 5% 7% 36%	1852
	11th to 20th	Day	18% 19% 4 7% 5% 4 3 2 5% 5% 28%	1890
	21st to end	Day	19% 18% 8% 9% 5% 5% 4 3 4 7% 18%	1717
December	1st to 10th	Day	17% 18% 8% 14% 6% 4 4 3 5% 6% 15%	2680
	11th to 20th	Day	20% 19% 7% 12% 7% 4 4 3 4 6% 13%	3070
	21st to end	Day	24% 22% 7% 12% 6% 4 4 3 3 3 11%	4401
January	1st to 10th	Night	17% 19% 9% 21% 6% 4 3 2 3 3 13%	7635
	11th to 20th	Night	10% 19% 9% 17% 8% 5% 6% 4 4 4 14%	7680
	21st to end	Night	18% 16% 6% 12% 5% 5% 4 3 4 5% 20%	8401
February	1st to 10th	Night	19% 14% 5% 12% 6% 4 4 3 5% 5% 22%	2730
	11th to 20th	Night	17% 15% 5% 12% 6% 4 4 4 5% 5% 22%	2564
	21st to end	Night	21% 14% 5% 11% 5% 4 4 3 5% 5% 24%	2076
March	1st to 10th	Night	20% 13% 4 8% 5% 4 3 3 4 5% 32%	5219
	11th to 20th	Night	13% 10% 4 6% 4 4 5% 4 5% 6% 39%	5090
	21st to end	Night	17% 10% 4 9% 5% 4 4 3 5% 5% 34%	5588
April	1st to 10th	Night	16% 15% 3 7% 5% 4 4 4 5% 6% 31%	2298
	11th to 20th	Night	15% 10% 3 8% 5% 4 5% 4 7% 6% 33%	1867
	21st to end	Night	16% 9% 2 7% 6% 4 4 4 6% 6% 37%	1890
May	1st to 10th	Night	21% 10% 4 9% 5% 4 4 4 6% 7% 27%	4123
	11th to 20th	Night	15% 7% 3 7% 5% 4 5% 3 5% 8% 38%	4086
	21st to end	Night	16% 6% 2 6% 5% 5% 5% 4 6% 7% 40%	4421
June	1st to 10th	Night	12% 6% 3 6% 5% 4 5% 4 5% 6% 44%	1655
	11th to 20th	Night	10% 5% 2 7% 5% 5% 5% 5% 7% 8% 41%	1484
	21st to end	Night	10% 5% 2 5% 6% 4 4 4 6% 10% 43%	1501
July	1st to 10th	Night	9% 4 2 6% 4 5% 5% 5% 6% 10% 44%	3618
	11th to 20th	Night	10% 4 2 6% 4 5% 5% 4 7% 8% 44%	4052
	21st to end	Night	8% 5% 2 6% 4 5% 4 4 6% 8% 48%	4427
August	1st to 10th	Night	11% 6% 3 7% 4 4 4 4 6% 9% 43%	2915
	11th to 20th	Night	12% 7% 2 7% 4 4 4 3 5% 7% 45%	2875
	21st to end	Night	9% 5% 3 6% 4 6% 6% 4 6% 6% 45%	3223
September	1st to 10th	Night	10% 6% 3 6% 5% 4 5% 4 6% 7% 46%	2140
	11th to 20th	Night	10% 5% 2 5% 5% 4 4 3 5% 7% 51%	2200
	21st to end	Night	16% 7% 2 8% 4 5% 5% 3 5% 5% 39%	2200
October	1st to 10th	Night	15% 5% 2 6% 4 4 4 3 5% 7% 45%	2305
	11th to 20th	Night	21% 8% 2 7% 5% 4 4 3 5% 6% 35%	2400
	21st to end	Night	26% 10% 3 7% 5% 5% 4 3 5% 5% 29%	2690
November	1st to 10th	Night	16% 13% 3 7% 5% 4 4 3 5% 6% 35%	2666
	11th to 20th	Night	18% 17% 4 9% 5% 4 4 3 5% 5% 26%	2730
	21st to end	Night	24% 18% 5% 7% 5% 4 4 3 5% 5% 21%	2899
December	1st to 10th	Night	17% 17% 8% 11% 6% 5% 5% 4 5% 7% 15%	4720
	11th to 20th	Night	19% 21% 7% 11% 5% 3 4 3 4 5% 18%	5345
	21st to end	Night	25% 19% 6% 12% 5% 4 4 3 4 5% 13%	6776

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% 8% 2	5259
	11th to 20th	Day	76% 4 8% 6% 6%	5280
	21st to end	Day	75% 4 6% 11% 4	5780
February	1st to 10th	Day	64% 4 11% 14% 6%	1890
	11th to 20th	Day	65% 4 9% 15% 6% 1	1949
	21st to end	Day	60% 5% 14% 13% 7% 1	1730
March	1st to 10th	Day	57% 5% 10% 21% 7%	4853
	11th to 20th	Day	48% 5% 17% 22% 7% 1	5090
	21st to end	Day	57% 4 12% 16% 11% 1	5586
April	1st to 10th	Day	52% 5% 12% 18% 12% 1	2340
	11th to 20th	Day	51% 4 13% 17% 14% 2	2702
	21st to end	Day	50% 4 12% 21% 11% 2	2730
May	1st to 10th	Day	54% 6% 9% 17% 13% 1	6027
	11th to 20th	Day	47% 7% 13% 21% 11% 2	5943
	21st to end	Day	43% 7% 11% 21% 13% 4	6447
June	1st to 10th	Day	41% 6% 11% 27% 14% 1	2740
	11th to 20th	Day	40% 7% 15% 22% 14% 2	2909
	21st to end	Day	36% 6% 15% 23% 17% 3	2889
July	1st to 10th	Day	35% 6% 12% 28% 17% 2	6291
	11th to 20th	Day	34% 8% 15% 26% 16% 1	5831
	21st to end	Day	37% 7% 13% 22% 20% 2	6240
August	1st to 10th	Day	38% 7% 16% 25% 14%	4221
	11th to 20th	Day	37% 7% 13% 33% 10% 1	4213
	21st to end	Day	35% 7% 16% 28% 13% 2	4652
September	1st to 10th	Day	37% 7% 14% 22% 17% 3	2246
	11th to 20th	Day	35% 6% 13% 27% 18% 1	2200
	21st to end	Day	44% 6% 11% 21% 18% 1	2200
October	1st to 10th	Day	31% 6% 14% 30% 19% 1	3407
	11th to 20th	Day	44% 5% 10% 20% 19% 1	3240
	21st to end	Day	43% 4 12% 23% 17% 1	3449
November	1st to 10th	Day	47% 5% 11% 23% 13% 1	1852
	11th to 20th	Day	57% 5% 9% 18% 10% 1	1890
	21st to end	Day	64% 6% 9% 15% 5%	1717
December	1st to 10th	Day	66% 7% 13% 12% 3	2680
	11th to 20th	Day	70% 5% 9% 13% 3	3066
	21st to end	Day	78% 5% 6% 7% 4	4401
January	1st to 10th	Night	76% 6% 6% 10% 3	7636
	11th to 20th	Night	73% 4 8% 9% 5% 1	7680
	21st to end	Night	65% 4 11% 13% 6%	8401
February	1st to 10th	Night	64% 5% 10% 15% 5% 1	2730
	11th to 20th	Night	63% 5% 10% 16% 7%	2566
	21st to end	Night	63% 4 10% 14% 7% 1	2076
March	1st to 10th	Night	55% 4 13% 20% 9%	5219
	11th to 20th	Night	42% 6% 15% 25% 11% 1	5090
	21st to end	Night	51% 6% 10% 19% 13% 1	5588
April	1st to 10th	Night	53% 5% 11% 16% 13% 2	2298
	11th to 20th	Night	49% 5% 11% 17% 15% 3	1867
	21st to end	Night	46% 5% 10% 21% 14% 3	1890
May	1st to 10th	Night	57% 6% 9% 13% 11% 4	4150
	11th to 20th	Night	44% 8% 10% 23% 14% 1	4087
	21st to end	Night	42% 7% 11% 22% 15% 2	4429
June	1st to 10th	Night	40% 6% 10% 25% 16% 3	1655
	11th to 20th	Night	37% 8% 13% 22% 17% 3	1484
	21st to end	Night	35% 8% 13% 25% 17% 2	1501
July	1st to 10th	Night	33% 8% 14% 24% 17% 5%	3580
	11th to 20th	Night	34% 9% 13% 26% 15% 3	4002
	21st to end	Night	33% 6% 13% 22% 24% 2	4297
August	1st to 10th	Night	38% 8% 12% 26% 15% 2	2904
	11th to 20th	Night	36% 7% 11% 31% 14% 1	2902
	21st to end	Night	35% 7% 12% 28% 14% 3	3223
September	1st to 10th	Night	36% 6% 12% 26% 16% 4	2140
	11th to 20th	Night	30% 7% 11% 28% 22% 2	2200
	21st to end	Night	44% 6% 10% 19% 19% 2	2200
October	1st to 10th	Night	30% 5% 8% 30% 26% 1	3773
	11th to 20th	Night	45% 5% 8% 21% 20% 1	3899
	21st to end	Night	42% 5% 9% 25% 17% 2	4338
November	1st to 10th	Night	47% 6% 11% 22% 13% 2	2666
	11th to 20th	Night	57% 6% 9% 17% 9% 2	2730
	21st to end	Night	64% 5% 10% 15% 5%	2899
December	1st to 10th	Night	63% 7% 12% 14% 4	4720
	11th to 20th	Night	67% 5% 10% 14% 3	5348
	21st to end	Night	73% 6% 9% 10% 2	6776

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% 34% 10% 4 1	330
	11th to 20th	Day	30% 29% 31% 7% 3	330
	21st to end	Day	29% 25% 33% 11% 2 1	363
February	1st to 10th	Day	30% 23% 33% 12% 2	330
	11th to 20th	Day	31% 27% 32% 8% 2	330
	21st to end	Day	28% 32% 32% 7% 1	273
March	1st to 10th	Day	25% 22% 35% 13% 4	447
	11th to 20th	Day	26% 22% 31% 15% 5% 1	540
	21st to end	Day	30% 19% 30% 17% 3 1	594
April	1st to 10th	Day	24% 20% 30% 19% 6% 1	540
	11th to 20th	Day	26% 22% 27% 16% 7% 3	532
	21st to end	Day	27% 14% 32% 18% 7% 2	540
May	1st to 10th	Day	27% 15% 30% 21% 6% 2	543
	11th to 20th	Day	19% 11% 34% 22% 11% 4	551
	21st to end	Day	16% 10% 26% 27% 15% 6%	573
June	1st to 10th	Day	15% 7% 32% 31% 12% 4	530
	11th to 20th	Day	14% 8% 28% 32% 15% 3	639
	21st to end	Day	11% 9% 29% 30% 18% 3	730
July	1st to 10th	Day	11% 4 24% 30% 24% 9%	721
	11th to 20th	Day	13% 5% 25% 29% 20% 8%	524
	21st to end	Day	10% 6% 23% 32% 21% 9%	576
August	1st to 10th	Day	10% 4 20% 32% 24% 10%	526
	11th to 20th	Day	13% 5% 20% 32% 20% 10%	519
	21st to end	Day	11% 5% 23% 27% 23% 10%	583
September	1st to 10th	Day	14% 8% 21% 25% 19% 12%	530
	11th to 20th	Day	11% 4 17% 27% 27% 13%	530
	21st to end	Day	20% 11% 24% 24% 12% 8%	530
October	1st to 10th	Day	13% 9% 26% 25% 20% 7%	530
	11th to 20th	Day	19% 16% 33% 22% 7% 2	530
	21st to end	Day	26% 19% 32% 18% 4 1	530
November	1st to 10th	Day	21% 21% 32% 18% 7% 2	330
	11th to 20th	Day	32% 22% 28% 14% 3 1	330
	21st to end	Day	32% 23% 33% 11% 1	239
December	1st to 10th	Day	24% 30% 26% 15% 4 1	220
	11th to 20th	Day	26% 29% 33% 11% 1	220
	21st to end	Day	33% 21% 32% 13% 2	325
January	1st to 10th	Night	29% 18% 31% 18% 4	840
	11th to 20th	Night	30% 20% 31% 15% 4	840
	21st to end	Night	27% 17% 31% 21% 4	924
February	1st to 10th	Night	28% 15% 33% 20% 4	840
	11th to 20th	Night	24% 18% 33% 22% 3	823
	21st to end	Night	30% 15% 36% 17% 3	692
March	1st to 10th	Night	25% 14% 32% 23% 6%	840
	11th to 20th	Night	23% 16% 32% 23% 6% 1	840
	21st to end	Night	25% 10% 31% 24% 9%	924
April	1st to 10th	Night	24% 14% 31% 26% 5%	838
	11th to 20th	Night	21% 12% 32% 25% 9% 1	623
	21st to end	Night	20% 9% 31% 31% 8% 1	630
May	1st to 10th	Night	22% 8% 25% 33% 10% 1	630
	11th to 20th	Night	22% 7% 25% 30% 15% 2	609
	21st to end	Night	13% 4 23% 34% 22% 4	650
June	1st to 10th	Night	13% 5% 28% 37% 16% 1	455
	11th to 20th	Night	10% 3 27% 43% 16% 1	400
	21st to end	Night	12% 3 25% 38% 21% 1	501
July	1st to 10th	Night	11% 2 15% 40% 29% 2	585
	11th to 20th	Night	10% 5% 19% 35% 27% 4	582
	21st to end	Night	10% 2 16% 41% 29% 2	657
August	1st to 10th	Night	9% 4 14% 43% 26% 5%	597
	11th to 20th	Night	11% 3 15% 38% 27% 5%	594
	21st to end	Night	10% 4 17% 35% 29% 5%	660
September	1st to 10th	Night	13% 6% 15% 36% 25% 5%	790
	11th to 20th	Night	12% 3 14% 34% 33% 4	800
	21st to end	Night	18% 9% 20% 29% 20% 4	800
October	1st to 10th	Night	18% 7% 24% 29% 20% 3	800
	11th to 20th	Night	24% 11% 30% 24% 10% 1	800
	21st to end	Night	30% 15% 28% 22% 5%	880
November	1st to 10th	Night	22% 14% 29% 24% 10% 1	820
	11th to 20th	Night	27% 16% 31% 18% 6% 1	840
	21st to end	Night	33% 15% 30% 17% 5%	840
December	1st to 10th	Night	30% 18% 28% 18% 4	840
	11th to 20th	Night	28% 18% 33% 18% 3	840
	21st to end	Night	32% 15% 31% 19% 3	924

Page generated at 2026-05-14 01:58:58. Version ac07

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