Lexington(SC)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lexington(SC) clear sky chart from 2005-11-06 to 2024-02-25.

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	12% 5% 2 5% 5% 3 5% 5% 6% 8% 44%	78827
	Night	12% 5% 2 5% 5% 3 4 5% 5% 7% 45%	80480
Transparency	Day	38% 6% 11% 20% 19% 6%	78550
	Night	38% 6% 10% 19% 20% 7%	80276
Seeing	Day	15% 8% 23% 24% 20% 10%	14299
	Night	15% 7% 23% 32% 20% 3	24476

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	15% 4 2 4 4 3 3 3 5% 8% 48%	2836
	11th to 20th	Day	13% 5% 2 4 4 2 3 3 4 6% 53%	2840
	21st to end	Day	18% 8% 3 5% 6% 2 3 3 3 5% 45%	3124
February	1st to 10th	Day	14% 6% 3 6% 4 3 5% 4 5% 8% 40%	1739
	11th to 20th	Day	19% 6% 2 5% 4 3 3 3 5% 5% 45%	1848
	21st to end	Day	18% 6% 2 5% 5% 2 4 4 5% 6% 43%	1564
March	1st to 10th	Day	13% 6% 2 3 3 3 4 3 3 5% 53%	1980
	11th to 20th	Day	15% 7% 3 4 4 3 5% 5% 6% 6% 42%	1980
	21st to end	Day	14% 7% 3 5% 4 3 5% 5% 5% 7% 42%	2178
April	1st to 10th	Day	9% 4 2 4 5% 3 5% 4 6% 7% 52%	1980
	11th to 20th	Day	10% 5% 3 5% 4 3 4 5% 6% 8% 47%	2098
	21st to end	Day	8% 4 2 4 4 3 4 5% 6% 9% 52%	2282
May	1st to 10th	Day	7% 4 2 5% 5% 3 4 5% 6% 8% 51%	2340
	11th to 20th	Day	12% 4 3 6% 5% 4 5% 6% 6% 7% 42%	2301
	21st to end	Day	10% 5% 2 7% 5% 4 4 6% 6% 9% 41%	2531
June	1st to 10th	Day	9% 6% 3 6% 6% 4 6% 6% 8% 10% 37%	2340
	11th to 20th	Day	7% 4 2 4 5% 4 6% 6% 7% 12% 43%	2340
	21st to end	Day	4 4 3 6% 6% 4 6% 6% 9% 13% 40%	2340
July	1st to 10th	Day	8% 5% 3 6% 8% 4 7% 7% 8% 10% 33%	2340
	11th to 20th	Day	7% 5% 3 6% 7% 5% 7% 7% 9% 12% 33%	2340
	21st to end	Day	6% 4 3 6% 7% 4 7% 8% 9% 13% 33%	2547
August	1st to 10th	Day	9% 6% 2 6% 7% 4 6% 8% 9% 11% 31%	2327
	11th to 20th	Day	13% 7% 3 6% 7% 4 6% 7% 8% 10% 31%	2303
	21st to end	Day	12% 6% 3 6% 7% 4 6% 7% 8% 10% 30%	2380
September	1st to 10th	Day	7% 5% 2 6% 6% 4 6% 6% 7% 9% 41%	1980
	11th to 20th	Day	13% 6% 2 5% 7% 4 3 5% 5% 8% 42%	1980
	21st to end	Day	16% 6% 3 5% 5% 3 4 4 6% 6% 43%	1980
October	1st to 10th	Day	14% 5% 2 4 4 3 3 4 4 7% 50%	1890
	11th to 20th	Day	11% 5% 2 4 5% 2 3 3 4 6% 57%	1800
	21st to end	Day	11% 5% 2 4 4 2 3 4 3 4 57%	1980
November	1st to 10th	Day	13% 5% 2 4 4 2 3 3 4 5% 55%	1857
	11th to 20th	Day	13% 5% 3 4 4 2 3 4 4 6% 54%	1785
	21st to end	Day	14% 5% 2 5% 5% 3 3 4 4 6% 49%	1710
December	1st to 10th	Day	16% 8% 3 5% 5% 3 5% 4 5% 7% 38%	1710
	11th to 20th	Day	16% 5% 2 3 3 2 4 4 4 6% 51%	2153
	21st to end	Day	18% 6% 3 5% 4 2 3 4 4 7% 43%	3124
January	1st to 10th	Night	16% 5% 3 4 4 2 3 4 4 6% 47%	4109
	11th to 20th	Night	10% 6% 2 6% 6% 4 5% 5% 5% 8% 44%	4120
	21st to end	Night	16% 8% 3 5% 4 3 4 4 4 4 45%	4532
February	1st to 10th	Night	16% 6% 3 4 6% 3 4 3 5% 6% 45%	2437
	11th to 20th	Night	18% 7% 3 5% 5% 2 4 3 4 5% 46%	2218
	21st to end	Night	15% 5% 3 5% 5% 3 5% 4 5% 7% 45%	1785
March	1st to 10th	Night	13% 5% 3 4 4 3 4 5% 4 6% 50%	1980
	11th to 20th	Night	15% 4 2 5% 5% 3 5% 5% 4 6% 45%	1980
	21st to end	Night	12% 5% 2 6% 5% 3 4 6% 6% 7% 44%	2178
April	1st to 10th	Night	10% 5% 2 4 3 3 5% 4 5% 7% 52%	1980
	11th to 20th	Night	11% 5% 2 5% 4 2 4 3 4 6% 53%	1811
	21st to end	Night	8% 4 2 4 5% 3 3 4 5% 7% 55%	1692
May	1st to 10th	Night	7% 4 2 5% 4 3 5% 5% 6% 9% 49%	1620
	11th to 20th	Night	10% 5% 3 5% 6% 4 5% 7% 7% 9% 39%	1592
	21st to end	Night	8% 5% 2 6% 5% 4 6% 5% 7% 9% 43%	1744
June	1st to 10th	Night	10% 6% 3 6% 5% 4 6% 6% 8% 11% 33%	1620
	11th to 20th	Night	8% 5% 3 4 6% 4 6% 5% 7% 11% 40%	1620
	21st to end	Night	5% 5% 3 6% 7% 3 7% 8% 9% 13% 34%	1620
July	1st to 10th	Night	7% 6% 3 6% 6% 5% 6% 7% 10% 11% 34%	1620
	11th to 20th	Night	7% 5% 3 6% 6% 4 6% 7% 10% 13% 33%	1620
	21st to end	Night	6% 5% 3 6% 7% 4 7% 6% 9% 12% 35%	1771
August	1st to 10th	Night	8% 5% 2 7% 8% 4 7% 8% 9% 12% 31%	1611
	11th to 20th	Night	11% 7% 3 7% 6% 3 6% 8% 7% 11% 31%	1598
	21st to end	Night	10% 6% 3 7% 7% 4 5% 7% 8% 11% 32%	1951
September	1st to 10th	Night	8% 4 3 6% 5% 3 4 6% 8% 11% 41%	1980
	11th to 20th	Night	12% 5% 2 7% 6% 5% 4 4 5% 8% 41%	1980
	21st to end	Night	15% 6% 2 5% 5% 3 4 5% 6% 5% 43%	1980
October	1st to 10th	Night	13% 4 2 5% 4 2 3 4 4 6% 52%	2067
	11th to 20th	Night	14% 4 2 4 4 2 3 3 4 5% 55%	2160
	21st to end	Night	10% 5% 2 4 4 2 3 5% 5% 5% 56%	2376
November	1st to 10th	Night	12% 5% 2 4 4 3 4 3 3 5% 56%	2221
	11th to 20th	Night	14% 6% 2 4 3 2 3 3 4 5% 53%	2393
	21st to end	Night	14% 4 2 4 4 3 4 4 5% 6% 49%	2470
December	1st to 10th	Night	16% 7% 3 5% 5% 3 4 4 5% 6% 43%	2470
	11th to 20th	Night	16% 5% 2 4 3 2 3 3 3 5% 52%	3042
	21st to end	Night	19% 6% 2 6% 5% 3 4 4 5% 6% 40%	4532

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	35% 4 6% 25% 22% 8%	2837
	11th to 20th	Day	33% 4 6% 18% 29% 10%	2840
	21st to end	Day	44% 3 3 17% 24% 9%	3124
February	1st to 10th	Day	42% 3 10% 19% 19% 6%	1739
	11th to 20th	Day	43% 4 5% 18% 24% 6%	1858
	21st to end	Day	43% 4 8% 15% 21% 9%	1564
March	1st to 10th	Day	35% 4 7% 22% 22% 11%	1980
	11th to 20th	Day	41% 5% 10% 19% 17% 7%	1980
	21st to end	Day	41% 5% 10% 19% 20% 5%	2178
April	1st to 10th	Day	32% 4 10% 20% 26% 7%	1980
	11th to 20th	Day	34% 5% 10% 20% 21% 10%	2098
	21st to end	Day	29% 6% 11% 27% 23% 5%	2282
May	1st to 10th	Day	32% 6% 14% 24% 21% 4	2340
	11th to 20th	Day	40% 8% 15% 18% 17% 1	2305
	21st to end	Day	39% 7% 12% 24% 15% 1	2531
June	1st to 10th	Day	40% 9% 16% 23% 11% 2	2340
	11th to 20th	Day	33% 8% 18% 27% 13% 1	2340
	21st to end	Day	33% 11% 18% 22% 13% 2	2340
July	1st to 10th	Day	41% 11% 18% 18% 9% 3	2275
	11th to 20th	Day	39% 14% 20% 18% 6% 2	2271
	21st to end	Day	37% 12% 22% 21% 8% 1	2405
August	1st to 10th	Day	42% 12% 17% 20% 7% 1	2314
	11th to 20th	Day	45% 12% 17% 18% 9% 1	2303
	21st to end	Day	46% 10% 17% 17% 8% 2	2380
September	1st to 10th	Day	36% 9% 14% 18% 18% 5%	1980
	11th to 20th	Day	40% 7% 11% 17% 21% 4	1980
	21st to end	Day	42% 5% 8% 20% 17% 7%	1980
October	1st to 10th	Day	36% 6% 6% 21% 24% 8%	1890
	11th to 20th	Day	30% 4 7% 25% 26% 8%	1800
	21st to end	Day	32% 3 5% 18% 30% 12%	1980
November	1st to 10th	Day	33% 4 6% 17% 27% 13%	1857
	11th to 20th	Day	33% 3 7% 22% 24% 11%	1785
	21st to end	Day	37% 4 8% 20% 22% 9%	1710
December	1st to 10th	Day	46% 5% 8% 17% 17% 7%	1710
	11th to 20th	Day	35% 4 7% 21% 24% 9%	2150
	21st to end	Day	42% 4 6% 21% 24% 4	3124
January	1st to 10th	Night	38% 4 5% 19% 26% 8%	4109
	11th to 20th	Night	38% 4 7% 20% 23% 8%	4120
	21st to end	Night	43% 5% 4 14% 26% 9%	4532
February	1st to 10th	Night	41% 3 7% 19% 21% 9%	2437
	11th to 20th	Night	43% 4 6% 18% 21% 9%	2219
	21st to end	Night	39% 5% 9% 18% 18% 11%	1785
March	1st to 10th	Night	36% 5% 7% 16% 23% 13%	1980
	11th to 20th	Night	40% 5% 11% 16% 21% 7%	1980
	21st to end	Night	37% 6% 11% 21% 19% 6%	2178
April	1st to 10th	Night	33% 4 11% 20% 24% 9%	1980
	11th to 20th	Night	34% 4 8% 21% 22% 11%	1811
	21st to end	Night	29% 5% 11% 26% 25% 5%	1692
May	1st to 10th	Night	30% 7% 14% 25% 20% 5%	1620
	11th to 20th	Night	39% 10% 16% 18% 16% 1	1593
	21st to end	Night	35% 9% 12% 26% 16% 2	1745
June	1st to 10th	Night	41% 10% 17% 20% 11% 1	1620
	11th to 20th	Night	36% 10% 18% 24% 10% 2	1620
	21st to end	Night	35% 15% 19% 18% 11% 2	1620
July	1st to 10th	Night	39% 11% 23% 14% 10% 3	1575
	11th to 20th	Night	37% 13% 25% 16% 7% 2	1566
	21st to end	Night	38% 13% 22% 18% 8% 1	1672
August	1st to 10th	Night	42% 13% 21% 18% 6% 1	1600
	11th to 20th	Night	42% 12% 19% 17% 8% 1	1598
	21st to end	Night	42% 12% 17% 18% 9% 2	1951
September	1st to 10th	Night	35% 9% 17% 19% 15% 5%	1980
	11th to 20th	Night	41% 7% 12% 17% 19% 4	1980
	21st to end	Night	41% 7% 12% 16% 19% 5%	1980
October	1st to 10th	Night	35% 5% 8% 18% 27% 7%	2067
	11th to 20th	Night	32% 3 9% 22% 23% 11%	2160
	21st to end	Night	30% 4 6% 20% 28% 13%	2376
November	1st to 10th	Night	32% 4 7% 15% 28% 14%	2221
	11th to 20th	Night	35% 4 6% 17% 25% 14%	2393
	21st to end	Night	36% 5% 7% 18% 24% 10%	2470
December	1st to 10th	Night	43% 5% 9% 18% 19% 7%	2470
	11th to 20th	Night	36% 3 7% 19% 27% 9%	3044
	21st to end	Night	45% 4 6% 19% 21% 4	4532

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	18% 17% 45% 16% 4	270
	11th to 20th	Day	19% 21% 35% 20% 5%	270
	21st to end	Day	22% 23% 36% 16% 3	297
February	1st to 10th	Day	19% 20% 36% 19% 6%	270
	11th to 20th	Day	31% 15% 36% 16% 3	270
	21st to end	Day	24% 15% 38% 17% 5%	254
March	1st to 10th	Day	17% 16% 34% 24% 8%	420
	11th to 20th	Day	20% 14% 40% 20% 6%	420
	21st to end	Day	19% 14% 35% 21% 10% 1	462
April	1st to 10th	Day	17% 14% 32% 24% 13%	420
	11th to 20th	Day	12% 14% 29% 24% 17% 4	412
	21st to end	Day	10% 10% 29% 28% 17% 6%	420
May	1st to 10th	Day	8% 12% 31% 27% 16% 5%	423
	11th to 20th	Day	15% 4 17% 32% 22% 10%	447
	21st to end	Day	12% 3 16% 25% 26% 18%	485
June	1st to 10th	Day	11% 2 14% 28% 31% 13%	450
	11th to 20th	Day	12% 3 14% 24% 28% 19%	450
	21st to end	Day	7% 2 14% 30% 30% 17%	450
July	1st to 10th	Day	9% 1 7% 22% 32% 29%	445
	11th to 20th	Day	9% 2 11% 19% 37% 23%	444
	21st to end	Day	6% 1 9% 28% 36% 19%	488
August	1st to 10th	Day	13% 3 11% 22% 31% 19%	446
	11th to 20th	Day	14% 2 9% 21% 34% 20%	439
	21st to end	Day	14% 3 11% 21% 29% 22%	495
September	1st to 10th	Day	8% 2 11% 28% 33% 19%	450
	11th to 20th	Day	16% 2 12% 24% 32% 14%	450
	21st to end	Day	19% 2 14% 25% 27% 12%	450
October	1st to 10th	Day	16% 3 20% 29% 23% 9%	450
	11th to 20th	Day	12% 5% 20% 30% 23% 10%	450
	21st to end	Day	13% 7% 26% 27% 20% 7%	495
November	1st to 10th	Day	17% 6% 25% 27% 19% 6%	455
	11th to 20th	Day	18% 10% 34% 27% 8% 2	345
	21st to end	Day	10% 13% 36% 25% 14% 1	270
December	1st to 10th	Day	26% 11% 35% 23% 5%	270
	11th to 20th	Day	22% 11% 36% 21% 9% 1	270
	21st to end	Day	26% 15% 33% 15% 7% 3	297
January	1st to 10th	Night	20% 13% 32% 27% 7%	760
	11th to 20th	Night	19% 11% 33% 31% 6%	760
	21st to end	Night	19% 13% 36% 28% 4	836
February	1st to 10th	Night	19% 12% 30% 33% 5%	760
	11th to 20th	Night	22% 12% 35% 29% 2	743
	21st to end	Night	17% 14% 35% 29% 5%	611
March	1st to 10th	Night	17% 10% 34% 35% 5%	720
	11th to 20th	Night	17% 10% 36% 28% 9%	720
	21st to end	Night	14% 11% 36% 29% 9% 1	792
April	1st to 10th	Night	14% 14% 30% 32% 10%	720
	11th to 20th	Night	13% 10% 31% 31% 15%	711
	21st to end	Night	11% 8% 28% 40% 13%	612
May	1st to 10th	Night	10% 7% 30% 38% 15%	540
	11th to 20th	Night	11% 3 25% 37% 20% 4	531
	21st to end	Night	10% 2 14% 37% 32% 5%	584
June	1st to 10th	Night	12% 2 15% 39% 26% 6%	540
	11th to 20th	Night	10% 1 13% 34% 31% 11%	540
	21st to end	Night	7% 3 11% 38% 34% 7%	540
July	1st to 10th	Night	9% 2 9% 35% 37% 9%	525
	11th to 20th	Night	10% 1 6% 30% 46% 8%	522
	21st to end	Night	7% 1 9% 32% 45% 6%	591
August	1st to 10th	Night	10% 1 10% 28% 43% 9%	537
	11th to 20th	Night	15% 1 6% 31% 40% 6%	534
	21st to end	Night	13% 1 9% 28% 43% 7%	739
September	1st to 10th	Night	10% 2 9% 30% 43% 6%	720
	11th to 20th	Night	14% 2 12% 27% 40% 5%	720
	21st to end	Night	17% 2 13% 33% 30% 4	720
October	1st to 10th	Night	15% 3 18% 31% 28% 5%	720
	11th to 20th	Night	16% 6% 20% 32% 24% 3	720
	21st to end	Night	13% 6% 23% 33% 24% 2	792
November	1st to 10th	Night	14% 6% 24% 34% 19% 3	740
	11th to 20th	Night	16% 8% 28% 32% 14% 1	760
	21st to end	Night	16% 7% 25% 36% 16% 1	760
December	1st to 10th	Night	18% 11% 26% 34% 10% 1	760
	11th to 20th	Night	19% 8% 25% 35% 12% 2	760
	21st to end	Night	24% 12% 25% 30% 8%	836

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