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 2026-08-30.

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% 6% 2 6% 4 4 5% 4 6% 8% 42%	143688
	Night	13% 6% 2 6% 4 4 4 4 6% 8% 44%	138539
Transparency	Day	38% 6% 12% 20% 18% 6%	147360
	Night	38% 6% 11% 18% 20% 7%	142939
Seeing	Day	15% 8% 24% 24% 20% 10%	17758
	Night	15% 7% 24% 32% 20% 3	27780

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	13% 4 2 5% 3 4 3 3 5% 7% 52%	5258
	11th to 20th	Day	12% 5% 2 4 3 3 2 2 3 5% 60%	5280
	21st to end	Day	18% 7% 3 6% 5% 3 4 3 4 5% 42%	5780
February	1st to 10th	Day	14% 7% 2 6% 4 4 5% 3 6% 8% 41%	1923
	11th to 20th	Day	20% 6% 2 6% 4 3 3 3 5% 5% 44%	2048
	21st to end	Day	17% 7% 2 5% 5% 4 3 4 5% 6% 43%	1783
March	1st to 10th	Day	19% 9% 3 6% 4 4 3 3 4 5% 40%	5045
	11th to 20th	Day	8% 4 2 4 4 4 4 4 5% 6% 55%	5090
	21st to end	Day	14% 7% 2 6% 4 4 4 3 4 5% 47%	5586
April	1st to 10th	Day	10% 4 2 4 4 4 4 3 7% 7% 51%	2310
	11th to 20th	Day	9% 5% 2 5% 3 4 4 4 7% 7% 50%	2452
	21st to end	Day	8% 5% 2 5% 5% 4 4 4 6% 8% 50%	2663
May	1st to 10th	Day	13% 7% 2 7% 4 4 5% 4 6% 9% 40%	7616
	11th to 20th	Day	13% 6% 2 6% 4 4 5% 4 6% 8% 40%	7626
	21st to end	Day	13% 6% 3 8% 5% 5% 5% 4 7% 8% 37%	8391
June	1st to 10th	Day	9% 6% 3 7% 5% 5% 6% 5% 8% 9% 37%	2730
	11th to 20th	Day	6% 5% 2 4 5% 5% 6% 4 8% 12% 43%	2730
	21st to end	Day	4 4 2 6% 5% 5% 6% 5% 9% 12% 40%	2730
July	1st to 10th	Day	9% 5% 2 7% 6% 6% 7% 6% 8% 12% 33%	7680
	11th to 20th	Day	6% 4 2 7% 6% 6% 7% 6% 10% 14% 32%	7680
	21st to end	Day	8% 6% 2 8% 6% 6% 7% 6% 10% 14% 29%	8340
August	1st to 10th	Day	21% 7% 2 7% 5% 6% 6% 5% 8% 10% 23%	4364
	11th to 20th	Day	11% 6% 2 7% 5% 5% 6% 5% 9% 11% 34%	4304
	21st to end	Day	7% 4 2 5% 4 4 5% 5% 7% 10% 46%	4412
September	1st to 10th	Day	7% 6% 2 6% 5% 5% 6% 4 7% 9% 42%	2200
	11th to 20th	Day	13% 6% 2 7% 6% 5% 4 4 5% 8% 41%	2200
	21st to end	Day	16% 6% 3 6% 4 4 3 3 6% 6% 42%	2200
October	1st to 10th	Day	13% 6% 2 5% 3 4 3 3 4 7% 49%	2100
	11th to 20th	Day	11% 5% 1 4 3 3 3 2 3 6% 59%	2000
	21st to end	Day	11% 4 2 5% 3 3 3 3 4 4 57%	2200
November	1st to 10th	Day	13% 5% 2 5% 4 3 3 2 4 5% 54%	2057
	11th to 20th	Day	13% 5% 2 4 3 2 2 3 4 6% 55%	1972
	21st to end	Day	12% 6% 2 6% 4 3 4 3 5% 6% 50%	1890
December	1st to 10th	Day	11% 7% 2 6% 4 4 4 3 5% 5% 50%	3020
	11th to 20th	Day	15% 6% 2 5% 3 3 4 3 5% 6% 48%	3463
	21st to end	Day	19% 6% 2 5% 3 3 3 2 5% 7% 45%	4565
January	1st to 10th	Night	11% 5% 2 6% 4 4 3 3 4 5% 54%	7635
	11th to 20th	Night	11% 5% 2 6% 3 4 3 3 5% 6% 52%	7680
	21st to end	Night	18% 8% 3 5% 4 4 3 3 4 4 45%	8401
February	1st to 10th	Night	15% 6% 2 5% 5% 4 4 2 5% 6% 46%	2693
	11th to 20th	Night	18% 7% 2 6% 5% 3 4 3 4 5% 44%	2458
	21st to end	Night	14% 6% 2 5% 4 4 4 3 5% 6% 45%	2021
March	1st to 10th	Night	19% 8% 3 6% 4 4 4 3 5% 6% 40%	5028
	11th to 20th	Night	10% 4 1 4 3 3 4 4 5% 7% 56%	5090
	21st to end	Night	13% 5% 2 5% 4 4 4 4 5% 7% 48%	5588
April	1st to 10th	Night	9% 5% 2 4 3 4 5% 4 6% 7% 51%	2310
	11th to 20th	Night	10% 5% 2 5% 4 3 4 3 4 6% 54%	2116
	21st to end	Night	8% 5% 2 5% 5% 4 4 3 6% 7% 53%	1974
May	1st to 10th	Night	10% 7% 3 7% 5% 5% 5% 4 6% 9% 39%	5237
	11th to 20th	Night	14% 5% 2 6% 4 4 5% 4 6% 9% 41%	5234
	21st to end	Night	13% 7% 3 7% 5% 5% 5% 5% 7% 8% 36%	5761
June	1st to 10th	Night	10% 7% 2 7% 5% 5% 6% 4 8% 10% 34%	1890
	11th to 20th	Night	8% 6% 2 5% 6% 6% 5% 3 7% 11% 40%	1890
	21st to end	Night	5% 5% 2 7% 6% 4 7% 6% 9% 13% 36%	1890
July	1st to 10th	Night	10% 7% 3 8% 6% 5% 6% 5% 8% 12% 32%	5278
	11th to 20th	Night	9% 5% 2 7% 5% 6% 7% 7% 10% 14% 26%	5277
	21st to end	Night	10% 8% 3 10% 7% 7% 6% 5% 8% 12% 22%	5736
August	1st to 10th	Night	21% 7% 3 9% 6% 5% 6% 5% 7% 9% 22%	3005
	11th to 20th	Night	11% 7% 2 8% 5% 5% 5% 5% 7% 11% 34%	2965
	21st to end	Night	6% 4 2 5% 4 3 4 4 7% 11% 49%	3644
September	1st to 10th	Night	8% 5% 2 7% 5% 4 4 5% 8% 10% 41%	2200
	11th to 20th	Night	12% 6% 2 9% 5% 6% 4 4 5% 8% 40%	2200
	21st to end	Night	16% 6% 2 6% 5% 4 4 3 6% 5% 43%	2200
October	1st to 10th	Night	12% 5% 3 6% 3 3 3 3 4 6% 52%	2297
	11th to 20th	Night	13% 4 2 4 3 2 2 3 4 5% 56%	2400
	21st to end	Night	10% 6% 2 5% 3 2 3 3 4 5% 57%	2640
November	1st to 10th	Night	12% 5% 2 5% 3 4 4 2 3 5% 54%	2461
	11th to 20th	Night	13% 6% 2 4 3 3 3 3 4 5% 54%	2645
	21st to end	Night	13% 4 2 4 4 4 4 4 5% 6% 49%	2730
December	1st to 10th	Night	13% 6% 2 5% 4 3 3 3 4 4 53%	4380
	11th to 20th	Night	16% 7% 2 6% 3 3 3 3 4 6% 46%	4952
	21st to end	Night	19% 6% 2 6% 4 4 4 3 4 6% 44%	6633

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	33% 3 8% 26% 23% 5%	5259
	11th to 20th	Day	30% 2 4 14% 36% 13%	5280
	21st to end	Day	46% 2 4 16% 20% 11%	5780
February	1st to 10th	Day	41% 3 9% 20% 20% 6%	1923
	11th to 20th	Day	44% 4 5% 18% 24% 6%	2058
	21st to end	Day	43% 4 8% 15% 21% 9%	1783
March	1st to 10th	Day	47% 4 6% 13% 20% 10%	5045
	11th to 20th	Day	29% 4 8% 16% 26% 18%	5090
	21st to end	Day	41% 4 6% 19% 21% 8%	5586
April	1st to 10th	Day	32% 4 11% 21% 25% 7%	2310
	11th to 20th	Day	31% 5% 9% 22% 22% 10%	2452
	21st to end	Day	31% 6% 11% 26% 22% 4	2663
May	1st to 10th	Day	42% 6% 14% 25% 12% 2	7651
	11th to 20th	Day	41% 6% 15% 22% 14% 2	7630
	21st to end	Day	44% 8% 14% 16% 16% 2	8405
June	1st to 10th	Day	40% 9% 16% 23% 11% 2	2730
	11th to 20th	Day	32% 8% 18% 27% 13% 1	2730
	21st to end	Day	32% 11% 19% 23% 13% 2	2730
July	1st to 10th	Day	40% 11% 21% 23% 5% 1	7615
	11th to 20th	Day	37% 15% 28% 17% 2	7611
	21st to end	Day	41% 12% 19% 19% 8% 1	8156
August	1st to 10th	Day	53% 10% 19% 14% 4	4351
	11th to 20th	Day	39% 11% 16% 20% 13% 1	4343
	21st to end	Day	31% 7% 15% 30% 16% 1	4412
September	1st to 10th	Day	35% 9% 14% 19% 18% 5%	2200
	11th to 20th	Day	41% 7% 11% 18% 19% 3	2200
	21st to end	Day	42% 5% 9% 21% 16% 7%	2200
October	1st to 10th	Day	34% 4 6% 17% 29% 10%	3425
	11th to 20th	Day	18% 2 4 18% 28% 30%	3240
	21st to end	Day	26% 3 4 20% 32% 15%	3538
November	1st to 10th	Day	34% 4 7% 17% 26% 13%	2057
	11th to 20th	Day	32% 3 7% 22% 26% 11%	1972
	21st to end	Day	36% 4 8% 20% 23% 9%	1890
December	1st to 10th	Day	37% 4 6% 17% 27% 9%	3020
	11th to 20th	Day	38% 3 11% 21% 20% 7%	3460
	21st to end	Day	40% 3 7% 23% 24% 3	4565
January	1st to 10th	Night	34% 3 6% 23% 28% 5%	7636
	11th to 20th	Night	34% 3 4 16% 32% 11%	7680
	21st to end	Night	44% 3 4 15% 25% 10%	8401
February	1st to 10th	Night	39% 3 7% 21% 21% 9%	2693
	11th to 20th	Night	43% 4 6% 18% 21% 8%	2459
	21st to end	Night	39% 5% 8% 17% 20% 12%	2021
March	1st to 10th	Night	45% 4 8% 12% 24% 8%	5028
	11th to 20th	Night	28% 4 7% 12% 30% 19%	5090
	21st to end	Night	36% 4 7% 21% 21% 11%	5588
April	1st to 10th	Night	33% 5% 11% 20% 22% 9%	2310
	11th to 20th	Night	31% 4 8% 22% 24% 11%	2116
	21st to end	Night	30% 5% 11% 26% 24% 5%	1974
May	1st to 10th	Night	41% 7% 14% 25% 12% 2	5264
	11th to 20th	Night	39% 7% 17% 22% 14% 1	5235
	21st to end	Night	44% 8% 12% 19% 15% 2	5771
June	1st to 10th	Night	40% 10% 16% 20% 12% 2	1890
	11th to 20th	Night	36% 9% 18% 24% 11% 2	1890
	21st to end	Night	34% 14% 20% 20% 12% 1	1890
July	1st to 10th	Night	43% 10% 23% 19% 5% 1	5235
	11th to 20th	Night	43% 15% 28% 12% 2 1	5226
	21st to end	Night	51% 12% 19% 11% 6% 1	5606
August	1st to 10th	Night	56% 10% 18% 13% 3 1	2994
	11th to 20th	Night	41% 10% 21% 19% 7% 1	2992
	21st to end	Night	27% 8% 15% 31% 16% 2	3644
September	1st to 10th	Night	35% 9% 16% 20% 15% 5%	2200
	11th to 20th	Night	42% 7% 12% 17% 18% 3	2200
	21st to end	Night	41% 6% 13% 17% 17% 5%	2200
October	1st to 10th	Night	34% 4 9% 17% 29% 7%	3752
	11th to 20th	Night	20% 2 5% 16% 26% 31%	3899
	21st to end	Night	26% 3 5% 18% 29% 19%	4252
November	1st to 10th	Night	33% 3 7% 15% 27% 14%	2461
	11th to 20th	Night	33% 3 6% 17% 27% 13%	2645
	21st to end	Night	35% 5% 7% 18% 25% 10%	2730
December	1st to 10th	Night	36% 3 6% 16% 30% 9%	4380
	11th to 20th	Night	40% 3 10% 18% 20% 8%	4954
	21st to end	Night	43% 4 6% 23% 21% 3	6633

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	17% 17% 46% 15% 4	330
	11th to 20th	Day	20% 21% 36% 19% 4	330
	21st to end	Day	21% 23% 38% 15% 2	363
February	1st to 10th	Day	18% 19% 39% 19% 5%	330
	11th to 20th	Day	33% 16% 35% 14% 2	330
	21st to end	Day	25% 16% 37% 17% 6%	326
March	1st to 10th	Day	19% 16% 31% 24% 10% 1	540
	11th to 20th	Day	18% 14% 40% 21% 7%	540
	21st to end	Day	17% 14% 37% 22% 10% 1	594
April	1st to 10th	Day	16% 13% 33% 24% 13% 1	540
	11th to 20th	Day	11% 13% 28% 27% 17% 3	532
	21st to end	Day	11% 9% 28% 29% 18% 6%	540
May	1st to 10th	Day	10% 12% 30% 28% 16% 4	543
	11th to 20th	Day	16% 4 20% 30% 20% 9%	567
	21st to end	Day	12% 5% 19% 24% 24% 15%	617
June	1st to 10th	Day	11% 3 15% 30% 29% 12%	570
	11th to 20th	Day	11% 3 14% 27% 28% 16%	570
	21st to end	Day	5% 2 13% 29% 34% 18%	570
July	1st to 10th	Day	8% 1 8% 22% 31% 30%	565
	11th to 20th	Day	7% 2 9% 18% 39% 25%	564
	21st to end	Day	6% 1 10% 28% 35% 20%	620
August	1st to 10th	Day	16% 3 11% 23% 29% 18%	566
	11th to 20th	Day	13% 2 9% 19% 34% 23%	559
	21st to end	Day	13% 2 12% 21% 29% 22%	619
September	1st to 10th	Day	8% 2 13% 30% 31% 17%	530
	11th to 20th	Day	16% 3 13% 24% 31% 14%	530
	21st to end	Day	19% 2 15% 26% 27% 12%	530
October	1st to 10th	Day	15% 3 20% 29% 24% 8%	530
	11th to 20th	Day	12% 5% 21% 31% 23% 8%	530
	21st to end	Day	14% 7% 26% 26% 20% 7%	583
November	1st to 10th	Day	17% 6% 25% 27% 19% 5%	535
	11th to 20th	Day	17% 10% 36% 25% 9% 2	412
	21st to end	Day	9% 14% 38% 26% 12% 1	330
December	1st to 10th	Day	26% 12% 36% 21% 4	330
	11th to 20th	Day	20% 11% 35% 24% 9% 1	330
	21st to end	Day	26% 14% 33% 18% 7% 2	363
January	1st to 10th	Night	19% 14% 33% 27% 7%	840
	11th to 20th	Night	18% 11% 35% 30% 6%	840
	21st to end	Night	19% 13% 37% 27% 3	924
February	1st to 10th	Night	18% 12% 31% 33% 5%	840
	11th to 20th	Night	22% 13% 35% 28% 2	823
	21st to end	Night	17% 15% 35% 28% 4	692
March	1st to 10th	Night	17% 10% 32% 34% 6%	840
	11th to 20th	Night	16% 11% 38% 27% 8%	840
	21st to end	Night	14% 12% 38% 28% 8%	924
April	1st to 10th	Night	13% 14% 31% 32% 10%	840
	11th to 20th	Night	12% 10% 32% 32% 14%	831
	21st to end	Night	11% 7% 28% 41% 13%	714
May	1st to 10th	Night	10% 7% 30% 38% 13%	630
	11th to 20th	Night	11% 4 27% 37% 19% 3	621
	21st to end	Night	11% 3 16% 37% 29% 4	683
June	1st to 10th	Night	12% 3 16% 39% 25% 5%	630
	11th to 20th	Night	10% 2 14% 34% 31% 9%	630
	21st to end	Night	7% 2 12% 38% 35% 6%	630
July	1st to 10th	Night	8% 2 9% 34% 39% 8%	615
	11th to 20th	Night	10% 1 6% 30% 44% 9%	612
	21st to end	Night	9% 1 10% 31% 43% 6%	690
August	1st to 10th	Night	14% 1 10% 27% 40% 8%	627
	11th to 20th	Night	14% 1 7% 30% 39% 8%	624
	21st to end	Night	13% 1 9% 29% 42% 6%	856
September	1st to 10th	Night	10% 2 10% 31% 40% 6%	800
	11th to 20th	Night	14% 2 12% 28% 39% 5%	800
	21st to end	Night	17% 2 13% 33% 30% 4	800
October	1st to 10th	Night	14% 3 18% 34% 27% 5%	800
	11th to 20th	Night	15% 6% 20% 33% 23% 3	800
	21st to end	Night	13% 6% 23% 33% 24% 2	880
November	1st to 10th	Night	15% 6% 24% 34% 18% 3	820
	11th to 20th	Night	16% 8% 28% 33% 13% 1	840
	21st to end	Night	15% 8% 26% 36% 15% 1	840
December	1st to 10th	Night	19% 11% 27% 33% 9% 1	840
	11th to 20th	Night	19% 9% 25% 35% 11% 1	840
	21st to end	Night	22% 12% 25% 32% 8%	924

Page generated at 2026-08-27 04:07:14. Version ac07

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