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 2024-01-22.

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 7% 6% 3 5% 5% 5% 7% 34%	75108
	Night	17% 11% 5% 7% 6% 3 4 4 5% 6% 31%	74798
Transparency	Day	34% 35% 8% 14% 8% 1	74825
	Night	37% 35% 7% 13% 7% 1	74602
Seeing	Day	20% 13% 28% 22% 12% 5%	13932
	Night	22% 11% 27% 27% 13% 2	23535

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	19% 16% 8% 11% 7% 5% 4 3 4 5% 18%	1706
	11th to 20th	Day	18% 19% 8% 11% 9% 5% 5% 3 4 4 13%	1710
	21st to end	Day	17% 18% 9% 12% 10% 4 5% 3 4 5% 14%	1791
February	1st to 10th	Day	18% 16% 6% 10% 8% 3 5% 4 4 5% 21%	1620
	11th to 20th	Day	16% 12% 7% 12% 10% 4 4 4 5% 6% 22%	1656
	21st to end	Day	18% 11% 5% 11% 7% 4 4 4 5% 6% 25%	1480
March	1st to 10th	Day	20% 11% 5% 8% 5% 3 3 4 5% 6% 29%	1899
	11th to 20th	Day	16% 11% 5% 7% 6% 4 4 5% 5% 6% 33%	1980
	21st to end	Day	22% 10% 4 8% 7% 3 4 4 4 6% 28%	2178
April	1st to 10th	Day	14% 11% 5% 6% 6% 3 5% 5% 5% 7% 35%	2005
	11th to 20th	Day	18% 10% 4 6% 5% 3 5% 4 5% 5% 36%	2312
	21st to end	Day	20% 9% 3 6% 5% 2 5% 4 4 7% 35%	2340
May	1st to 10th	Day	17% 8% 4 6% 6% 4 5% 5% 6% 6% 35%	2340
	11th to 20th	Day	16% 7% 3 6% 5% 3 4 6% 6% 6% 36%	2301
	21st to end	Day	9% 6% 3 5% 5% 3 6% 5% 6% 9% 42%	2531
June	1st to 10th	Day	13% 5% 2 5% 5% 3 5% 6% 7% 8% 41%	2466
	11th to 20th	Day	11% 5% 2 6% 5% 3 5% 5% 6% 9% 43%	2617
	21st to end	Day	10% 4 2 4 5% 3 6% 5% 7% 10% 44%	2601
July	1st to 10th	Day	9% 4 2 5% 5% 3 5% 5% 5% 10% 47%	2520
	11th to 20th	Day	10% 4 2 4 5% 2 4 5% 7% 10% 46%	2340
	21st to end	Day	9% 5% 2 4 5% 4 5% 5% 7% 9% 45%	2547
August	1st to 10th	Day	8% 4 2 5% 6% 3 4 5% 7% 9% 46%	2327
	11th to 20th	Day	9% 6% 2 6% 5% 4 5% 6% 7% 9% 40%	2303
	21st to end	Day	10% 5% 3 4 5% 2 5% 6% 6% 10% 44%	2566
September	1st to 10th	Day	15% 5% 2 5% 5% 3 5% 5% 5% 7% 44%	2022
	11th to 20th	Day	11% 6% 3 5% 5% 3 5% 5% 6% 9% 44%	1980
	21st to end	Day	18% 7% 2 5% 5% 3 4 5% 5% 6% 40%	1980
October	1st to 10th	Day	15% 7% 3 6% 6% 3 4 5% 5% 7% 39%	1886
	11th to 20th	Day	20% 7% 4 6% 6% 3 4 4 5% 7% 35%	1800
	21st to end	Day	23% 12% 3 7% 6% 3 4 5% 5% 7% 26%	1933
November	1st to 10th	Day	14% 10% 4 7% 5% 3 4 4 5% 7% 36%	1672
	11th to 20th	Day	18% 18% 5% 6% 6% 2 3 3 5% 6% 28%	1710
	21st to end	Day	19% 17% 7% 8% 6% 3 5% 4 5% 7% 20%	1554
December	1st to 10th	Day	18% 21% 8% 10% 7% 3 4 4 4 5% 16%	1520
	11th to 20th	Day	18% 15% 8% 13% 6% 3 5% 5% 5% 6% 16%	1910
	21st to end	Day	25% 22% 8% 10% 7% 3 4 4 3 4 10%	3005
January	1st to 10th	Night	20% 16% 8% 10% 7% 3 4 3 3 5% 20%	2459
	11th to 20th	Night	19% 19% 7% 13% 9% 4 4 3 4 4 15%	2470
	21st to end	Night	18% 17% 8% 11% 8% 4 4 3 4 5% 19%	2599
February	1st to 10th	Night	21% 13% 5% 11% 8% 4 4 4 4 5% 21%	2340
	11th to 20th	Night	19% 15% 6% 10% 7% 4 4 4 5% 5% 22%	2188
	21st to end	Night	22% 11% 7% 9% 6% 3 5% 3 4 5% 24%	1776
March	1st to 10th	Night	17% 12% 6% 7% 7% 3 4 4 4 6% 31%	2060
	11th to 20th	Night	16% 10% 4 5% 6% 4 4 6% 5% 6% 35%	1980
	21st to end	Night	21% 11% 4 6% 6% 3 4 3 4 6% 31%	2178
April	1st to 10th	Night	15% 13% 4 6% 5% 3 4 5% 5% 7% 33%	1971
	11th to 20th	Night	16% 9% 3 7% 5% 3 5% 5% 7% 7% 34%	1597
	21st to end	Night	16% 7% 3 6% 6% 3 5% 5% 6% 7% 37%	1620
May	1st to 10th	Night	18% 9% 4 8% 6% 3 5% 5% 6% 7% 29%	1620
	11th to 20th	Night	17% 7% 4 6% 5% 3 4 4 6% 7% 37%	1592
	21st to end	Night	9% 4 2 5% 5% 4 5% 6% 7% 9% 44%	1744
June	1st to 10th	Night	11% 5% 4 6% 4 3 5% 6% 6% 6% 44%	1490
	11th to 20th	Night	11% 4 2 5% 6% 4 5% 6% 7% 9% 41%	1336
	21st to end	Night	10% 5% 2 5% 6% 3 4 5% 6% 11% 43%	1350
July	1st to 10th	Night	9% 4 2 4 4 3 6% 6% 6% 8% 48%	1440
	11th to 20th	Night	9% 3 2 5% 5% 3 6% 5% 7% 8% 47%	1615
	21st to end	Night	8% 4 2 4 5% 3 6% 6% 6% 9% 46%	1771
August	1st to 10th	Night	7% 4 3 5% 4 3 4 5% 6% 8% 50%	1611
	11th to 20th	Night	10% 6% 2 5% 5% 3 5% 6% 6% 8% 44%	1598
	21st to end	Night	10% 6% 2 6% 5% 3 5% 5% 5% 7% 46%	1782
September	1st to 10th	Night	11% 5% 3 5% 6% 3 6% 5% 6% 7% 44%	1924
	11th to 20th	Night	12% 5% 2 4 6% 3 4 4 5% 7% 49%	1980
	21st to end	Night	14% 6% 2 7% 5% 4 6% 4 5% 6% 41%	1980
October	1st to 10th	Night	15% 6% 2 6% 5% 3 4 4 5% 7% 42%	2074
	11th to 20th	Night	22% 7% 3 6% 6% 3 4 4 5% 6% 34%	2160
	21st to end	Night	27% 10% 3 6% 6% 3 4 4 5% 5% 27%	2420
November	1st to 10th	Night	17% 12% 4 6% 5% 3 4 4 5% 6% 35%	2406
	11th to 20th	Night	19% 16% 5% 8% 6% 3 4 4 5% 5% 25%	2470
	21st to end	Night	24% 16% 6% 6% 5% 3 4 4 4 5% 22%	2622
December	1st to 10th	Night	21% 19% 9% 8% 7% 3 4 4 3 5% 17%	2660
	11th to 20th	Night	18% 19% 7% 9% 6% 2 3 5% 5% 5% 20%	3285
	21st to end	Night	28% 20% 7% 8% 7% 3 4 4 4 5% 12%	4630

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	47% 38% 7% 7% 1	1707
	11th to 20th	Day	49% 38% 6% 6% 1	1710
	21st to end	Day	52% 35% 5% 6% 2	1791
February	1st to 10th	Day	44% 35% 8% 9% 5%	1620
	11th to 20th	Day	44% 36% 7% 8% 5% 1	1665
	21st to end	Day	43% 34% 8% 10% 4	1480
March	1st to 10th	Day	37% 35% 8% 16% 4	1899
	11th to 20th	Day	36% 35% 8% 12% 7% 1	1980
	21st to end	Day	40% 35% 6% 15% 4 1	2178
April	1st to 10th	Day	31% 35% 8% 15% 11% 1	2005
	11th to 20th	Day	35% 34% 6% 13% 10% 1	2312
	21st to end	Day	34% 35% 7% 16% 7% 2	2340
May	1st to 10th	Day	33% 35% 7% 15% 10% 1	2340
	11th to 20th	Day	31% 35% 6% 13% 12% 2	2305
	21st to end	Day	25% 36% 10% 18% 9% 1	2531
June	1st to 10th	Day	26% 35% 9% 19% 10% 1	2466
	11th to 20th	Day	23% 35% 12% 18% 10% 2	2617
	21st to end	Day	24% 36% 10% 17% 11% 3	2601
July	1st to 10th	Day	22% 36% 8% 18% 15% 1	2451
	11th to 20th	Day	23% 36% 9% 20% 11% 1	2271
	21st to end	Day	23% 37% 10% 17% 12% 1	2405
August	1st to 10th	Day	25% 35% 9% 21% 10%	2314
	11th to 20th	Day	25% 35% 10% 19% 9% 2	2303
	21st to end	Day	23% 36% 8% 16% 14% 3	2566
September	1st to 10th	Day	28% 36% 9% 14% 12% 2	2022
	11th to 20th	Day	26% 35% 10% 18% 11%	1980
	21st to end	Day	34% 34% 7% 13% 11%	1980
October	1st to 10th	Day	31% 36% 5% 19% 9%	1886
	11th to 20th	Day	38% 34% 8% 13% 6% 1	1800
	21st to end	Day	39% 35% 7% 12% 7% 1	1933
November	1st to 10th	Day	26% 39% 6% 17% 10% 1	1672
	11th to 20th	Day	37% 38% 6% 12% 7% 1	1710
	21st to end	Day	41% 39% 5% 11% 4	1554
December	1st to 10th	Day	46% 38% 7% 7% 2	1520
	11th to 20th	Day	51% 31% 5% 11% 2	1906
	21st to end	Day	65% 24% 6% 4 1	3005
January	1st to 10th	Night	46% 38% 5% 8% 3	2459
	11th to 20th	Night	48% 38% 5% 7% 1	2470
	21st to end	Night	47% 36% 7% 9% 2	2599
February	1st to 10th	Night	43% 35% 8% 10% 3	2340
	11th to 20th	Night	44% 35% 6% 9% 4	2190
	21st to end	Night	43% 34% 7% 10% 5% 1	1776
March	1st to 10th	Night	37% 35% 7% 15% 6%	2060
	11th to 20th	Night	34% 36% 7% 13% 9% 1	1980
	21st to end	Night	38% 35% 5% 16% 5% 1	2178
April	1st to 10th	Night	34% 35% 7% 12% 11% 2	1971
	11th to 20th	Night	33% 33% 7% 14% 11% 3	1597
	21st to end	Night	32% 35% 6% 14% 10% 2	1620
May	1st to 10th	Night	38% 35% 6% 12% 7% 2	1620
	11th to 20th	Night	30% 36% 6% 12% 13% 3	1593
	21st to end	Night	24% 37% 9% 19% 10% 2	1745
June	1st to 10th	Night	26% 36% 7% 18% 10% 3	1490
	11th to 20th	Night	24% 36% 12% 14% 13% 2	1336
	21st to end	Night	26% 36% 8% 16% 13% 1	1350
July	1st to 10th	Night	24% 36% 6% 17% 15% 3	1400
	11th to 20th	Night	22% 37% 8% 19% 12% 1	1562
	21st to end	Night	23% 38% 10% 15% 13% 2	1672
August	1st to 10th	Night	23% 35% 9% 21% 10% 1	1600
	11th to 20th	Night	23% 35% 9% 20% 10% 3	1598
	21st to end	Night	24% 35% 7% 16% 14% 3	1782
September	1st to 10th	Night	27% 35% 6% 17% 12% 3	1924
	11th to 20th	Night	26% 36% 6% 18% 14% 1	1980
	21st to end	Night	33% 35% 7% 13% 11% 1	1980
October	1st to 10th	Night	30% 35% 6% 15% 13% 1	2074
	11th to 20th	Night	36% 35% 7% 13% 8% 1	2160
	21st to end	Night	40% 36% 4 13% 6% 1	2420
November	1st to 10th	Night	28% 39% 6% 15% 10% 1	2406
	11th to 20th	Night	39% 38% 5% 11% 5% 1	2470
	21st to end	Night	42% 38% 6% 10% 3	2622
December	1st to 10th	Night	47% 39% 5% 8% 2	2660
	11th to 20th	Night	47% 31% 9% 11% 2	3288
	21st to end	Night	63% 23% 8% 5% 1	4630

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% 23% 31% 10% 5% 1	270
	11th to 20th	Day	30% 26% 33% 7% 4	270
	21st to end	Day	28% 25% 31% 13% 2 1	267
February	1st to 10th	Day	35% 21% 34% 10%	240
	11th to 20th	Day	33% 25% 34% 7% 2	240
	21st to end	Day	29% 33% 31% 7% 1	198
March	1st to 10th	Day	27% 23% 31% 14% 5%	339
	11th to 20th	Day	25% 21% 31% 17% 5% 1	420
	21st to end	Day	31% 17% 28% 18% 4 1	462
April	1st to 10th	Day	23% 17% 31% 21% 7% 1	420
	11th to 20th	Day	27% 19% 26% 16% 8% 4	412
	21st to end	Day	30% 13% 31% 18% 6% 2	420
May	1st to 10th	Day	27% 13% 29% 21% 7% 3	423
	11th to 20th	Day	19% 11% 34% 22% 10% 4	447
	21st to end	Day	14% 9% 25% 28% 17% 7%	485
June	1st to 10th	Day	13% 6% 33% 31% 13% 4	450
	11th to 20th	Day	14% 7% 29% 31% 17% 3	547
	21st to end	Day	12% 9% 30% 30% 17% 3	630
July	1st to 10th	Day	11% 4 23% 29% 24% 10%	621
	11th to 20th	Day	14% 4 25% 28% 20% 9%	444
	21st to end	Day	10% 6% 25% 31% 20% 8%	488
August	1st to 10th	Day	11% 3 20% 33% 23% 11%	446
	11th to 20th	Day	14% 5% 20% 33% 19% 10%	439
	21st to end	Day	12% 5% 24% 26% 23% 10%	495
September	1st to 10th	Day	16% 7% 22% 26% 18% 11%	450
	11th to 20th	Day	13% 5% 19% 26% 26% 12%	450
	21st to end	Day	18% 12% 26% 23% 13% 8%	450
October	1st to 10th	Day	15% 10% 27% 24% 18% 6%	450
	11th to 20th	Day	20% 17% 34% 22% 6% 2	450
	21st to end	Day	29% 19% 31% 17% 3 1	448
November	1st to 10th	Day	19% 22% 31% 18% 7% 3	270
	11th to 20th	Day	31% 21% 27% 16% 4 1	270
	21st to end	Day	30% 23% 36% 10% 1	196
December	1st to 10th	Day	23% 32% 24% 15% 4 1	180
	11th to 20th	Day	24% 29% 36% 11%	180
	21st to end	Day	30% 22% 34% 12% 2	265
January	1st to 10th	Night	30% 18% 31% 17% 4	760
	11th to 20th	Night	31% 18% 30% 16% 4	760
	21st to end	Night	26% 15% 33% 22% 5%	800
February	1st to 10th	Night	29% 14% 33% 20% 3	720
	11th to 20th	Night	26% 17% 33% 21% 3	703
	21st to end	Night	30% 14% 35% 17% 3	592
March	1st to 10th	Night	24% 14% 32% 24% 6%	720
	11th to 20th	Night	22% 14% 32% 24% 7% 1	720
	21st to end	Night	26% 9% 29% 25% 11%	792
April	1st to 10th	Night	22% 14% 30% 28% 5%	719
	11th to 20th	Night	21% 11% 32% 25% 10% 2	533
	21st to end	Night	21% 8% 31% 30% 9% 1	540
May	1st to 10th	Night	23% 7% 25% 33% 11% 1	540
	11th to 20th	Night	23% 5% 24% 31% 15% 2	531
	21st to end	Night	13% 2 23% 34% 24% 4	584
June	1st to 10th	Night	12% 4 28% 38% 17% 1	410
	11th to 20th	Night	11% 3 26% 43% 17% 1	360
	21st to end	Night	12% 3 25% 38% 21% 1	450
July	1st to 10th	Night	11% 2 15% 38% 31% 3	525
	11th to 20th	Night	10% 4 19% 35% 27% 5%	522
	21st to end	Night	10% 2 16% 41% 29% 2	591
August	1st to 10th	Night	8% 4 14% 42% 26% 6%	537
	11th to 20th	Night	11% 3 14% 39% 28% 6%	534
	21st to end	Night	11% 4 17% 33% 28% 5%	594
September	1st to 10th	Night	13% 6% 14% 37% 25% 5%	710
	11th to 20th	Night	13% 4 15% 34% 30% 4	720
	21st to end	Night	16% 8% 21% 30% 20% 4	720
October	1st to 10th	Night	19% 7% 25% 27% 20% 3	720
	11th to 20th	Night	25% 11% 31% 23% 9% 1	720
	21st to end	Night	31% 16% 26% 22% 5%	792
November	1st to 10th	Night	23% 14% 27% 23% 11% 1	740
	11th to 20th	Night	28% 15% 31% 18% 7% 1	760
	21st to end	Night	33% 14% 29% 18% 6%	760
December	1st to 10th	Night	31% 18% 28% 18% 5% 1	760
	11th to 20th	Night	28% 18% 32% 18% 3	760
	21st to end	Night	33% 15% 32% 18% 3	836

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