Gastonia
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gastonia clear sky chart from 2005-11-06 to 2026-09-29.

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	13% 6% 2 6% 4 4 4 4 6% 8% 43%	149031
	Night	14% 6% 2 6% 4 4 4 4 5% 7% 44%	142370
Transparency	Day	37% 7% 13% 21% 17% 5%	152690
	Night	38% 7% 11% 19% 19% 6%	146783
Seeing	Day	16% 8% 22% 24% 20% 10%	17811
	Night	16% 7% 24% 32% 20% 3	27835

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% 7% 2 5% 3 3 2 2 3 5% 52%	5258
	11th to 20th	Day	11% 6% 2 4 2 3 3 2 3 3 61%	5280
	21st to end	Day	20% 8% 3 5% 4 4 4 3 4 5% 42%	5780
February	1st to 10th	Day	15% 7% 2 5% 4 4 4 4 7% 6% 43%	1890
	11th to 20th	Day	21% 6% 2 5% 3 3 3 3 5% 5% 45%	2037
	21st to end	Day	19% 8% 3 6% 4 4 4 3 4 6% 41%	1767
March	1st to 10th	Day	20% 7% 2 6% 3 3 3 3 4 6% 41%	5045
	11th to 20th	Day	9% 5% 2 6% 3 3 3 2 4 7% 54%	5090
	21st to end	Day	17% 7% 2 5% 4 3 3 3 4 5% 48%	5586
April	1st to 10th	Day	11% 5% 1 5% 3 4 4 4 6% 8% 49%	2310
	11th to 20th	Day	12% 5% 2 5% 4 3 4 4 5% 7% 50%	2474
	21st to end	Day	13% 5% 2 6% 4 4 4 4 5% 7% 48%	2704
May	1st to 10th	Day	12% 7% 2 7% 4 5% 5% 4 7% 9% 38%	7616
	11th to 20th	Day	15% 6% 2 6% 4 4 5% 4 6% 8% 40%	7626
	21st to end	Day	14% 7% 2 7% 5% 5% 5% 4 6% 9% 36%	8391
June	1st to 10th	Day	8% 6% 3 6% 4 5% 5% 5% 8% 11% 38%	2730
	11th to 20th	Day	7% 5% 2 6% 5% 5% 5% 5% 8% 10% 42%	2730
	21st to end	Day	6% 4 2 6% 5% 5% 5% 5% 9% 12% 41%	2730
July	1st to 10th	Day	7% 4 2 6% 5% 4 5% 5% 8% 12% 42%	7680
	11th to 20th	Day	8% 5% 2 7% 5% 6% 7% 5% 8% 13% 34%	7680
	21st to end	Day	11% 6% 3 7% 5% 6% 6% 5% 8% 11% 31%	8340
August	1st to 10th	Day	18% 7% 3 7% 6% 6% 6% 6% 9% 12% 22%	6014
	11th to 20th	Day	7% 4 2 5% 4 5% 5% 4 8% 12% 45%	5951
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 6% 9% 49%	6203
September	1st to 10th	Day	8% 5% 2 5% 4 5% 6% 5% 7% 9% 45%	2315
	11th to 20th	Day	13% 6% 2 6% 4 4 4 5% 6% 8% 43%	2310
	21st to end	Day	18% 6% 2 6% 4 4 4 4 5% 6% 40%	2288
October	1st to 10th	Day	14% 5% 2 3 3 3 3 2 4 5% 55%	2090
	11th to 20th	Day	13% 5% 1 4 3 3 3 2 3 6% 59%	2000
	21st to end	Day	14% 5% 2 4 3 3 2 2 4 4 58%	2200
November	1st to 10th	Day	13% 6% 2 5% 3 2 3 2 4 5% 54%	2057
	11th to 20th	Day	13% 5% 2 3 3 3 3 3 5% 6% 55%	1921
	21st to end	Day	14% 5% 2 5% 4 3 4 3 5% 5% 50%	1890
December	1st to 10th	Day	14% 6% 2 5% 3 3 3 2 4 5% 53%	3020
	11th to 20th	Day	18% 6% 3 6% 4 4 4 3 5% 6% 42%	3463
	21st to end	Day	21% 6% 2 4 3 3 3 3 4 6% 45%	4565
January	1st to 10th	Night	13% 6% 2 5% 3 3 3 2 4 5% 56%	7635
	11th to 20th	Night	12% 6% 2 4 3 3 3 3 3 4 57%	7680
	21st to end	Night	20% 7% 2 5% 3 3 3 3 4 5% 45%	8401
February	1st to 10th	Night	14% 6% 2 5% 4 4 4 3 5% 6% 47%	2730
	11th to 20th	Night	20% 7% 2 5% 4 3 3 3 4 4 43%	2466
	21st to end	Night	16% 7% 2 5% 4 3 4 4 5% 7% 45%	2037
March	1st to 10th	Night	18% 6% 2 6% 4 3 3 3 4 6% 45%	5028
	11th to 20th	Night	9% 4 2 4 3 3 4 4 5% 7% 55%	5090
	21st to end	Night	16% 4 2 5% 4 4 4 3 5% 6% 48%	5588
April	1st to 10th	Night	12% 5% 2 5% 4 4 4 3 6% 7% 48%	2310
	11th to 20th	Night	11% 4 2 5% 3 3 3 4 5% 7% 52%	2092
	21st to end	Night	11% 5% 2 5% 5% 5% 4 4 5% 7% 48%	1932
May	1st to 10th	Night	13% 6% 3 7% 5% 4 4 4 6% 9% 38%	5237
	11th to 20th	Night	15% 6% 2 6% 5% 4 5% 3 6% 8% 39%	5234
	21st to end	Night	18% 7% 2 7% 5% 4 4 4 6% 8% 33%	5761
June	1st to 10th	Night	10% 6% 2 7% 6% 6% 6% 5% 7% 10% 35%	1890
	11th to 20th	Night	9% 6% 2 7% 6% 6% 5% 5% 7% 10% 37%	1890
	21st to end	Night	6% 5% 2 6% 6% 6% 6% 5% 9% 12% 38%	1890
July	1st to 10th	Night	8% 6% 3 8% 6% 6% 7% 5% 8% 11% 33%	5278
	11th to 20th	Night	10% 6% 3 7% 6% 5% 6% 6% 10% 12% 29%	5277
	21st to end	Night	13% 8% 4 9% 6% 6% 7% 5% 8% 10% 25%	5736
August	1st to 10th	Night	20% 10% 3 8% 5% 5% 6% 5% 8% 9% 20%	4135
	11th to 20th	Night	8% 6% 2 7% 6% 5% 7% 5% 8% 12% 35%	4095
	21st to end	Night	7% 5% 2 7% 5% 5% 5% 4 6% 9% 44%	4861
September	1st to 10th	Night	9% 6% 2 6% 4 4 5% 4 7% 9% 45%	2299
	11th to 20th	Night	15% 7% 3 7% 5% 4 5% 5% 5% 7% 38%	2310
	21st to end	Night	18% 7% 2 7% 4 4 4 4 5% 6% 40%	2289
October	1st to 10th	Night	14% 5% 1 5% 3 4 4 3 4 6% 50%	2310
	11th to 20th	Night	14% 5% 2 4 3 3 3 3 4 5% 54%	2400
	21st to end	Night	13% 4 2 5% 2 3 3 3 3 5% 58%	2640
November	1st to 10th	Night	14% 5% 2 5% 4 3 3 2 4 5% 53%	2461
	11th to 20th	Night	12% 4 2 5% 4 3 3 3 5% 5% 53%	2693
	21st to end	Night	13% 4 2 5% 4 3 5% 3 5% 7% 50%	2730
December	1st to 10th	Night	16% 7% 2 4 3 3 3 2 4 5% 51%	4380
	11th to 20th	Night	20% 7% 2 5% 4 3 3 3 4 5% 44%	4952
	21st to end	Night	20% 4 2 4 3 3 3 3 4 6% 47%	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	37% 3 8% 21% 26% 6%	5259
	11th to 20th	Day	30% 2 4 12% 38% 14%	5280
	21st to end	Day	46% 3 4 18% 20% 10%	5780
February	1st to 10th	Day	38% 5% 11% 21% 19% 5%	1890
	11th to 20th	Day	41% 5% 7% 20% 20% 6%	2047
	21st to end	Day	45% 4 7% 15% 21% 7%	1767
March	1st to 10th	Day	44% 4 6% 14% 19% 12%	5045
	11th to 20th	Day	30% 5% 7% 15% 25% 18%	5090
	21st to end	Day	40% 4 7% 24% 21% 5%	5586
April	1st to 10th	Day	31% 6% 12% 22% 24% 6%	2310
	11th to 20th	Day	33% 5% 10% 22% 22% 8%	2474
	21st to end	Day	35% 6% 12% 24% 19% 4	2704
May	1st to 10th	Day	40% 9% 15% 22% 13% 1	7651
	11th to 20th	Day	40% 8% 13% 23% 13% 2	7630
	21st to end	Day	44% 9% 14% 18% 13% 3	8405
June	1st to 10th	Day	36% 10% 15% 25% 12% 1	2730
	11th to 20th	Day	33% 10% 19% 23% 13% 1	2730
	21st to end	Day	32% 11% 19% 22% 14% 2	2730
July	1st to 10th	Day	32% 10% 21% 28% 8% 1	7615
	11th to 20th	Day	38% 13% 27% 17% 5%	7611
	21st to end	Day	43% 11% 16% 20% 9% 1	8156
August	1st to 10th	Day	50% 13% 20% 14% 3	6001
	11th to 20th	Day	30% 9% 26% 25% 9% 1	5990
	21st to end	Day	30% 8% 15% 32% 13% 1	6203
September	1st to 10th	Day	32% 10% 14% 21% 19% 3	2315
	11th to 20th	Day	37% 8% 14% 18% 19% 3	2310
	21st to end	Day	44% 6% 10% 18% 16% 4	2288
October	1st to 10th	Day	29% 4 7% 22% 29% 10%	3402
	11th to 20th	Day	20% 3 5% 19% 29% 24%	3240
	21st to end	Day	27% 3 5% 25% 25% 15%	3538
November	1st to 10th	Day	33% 5% 7% 19% 28% 8%	2057
	11th to 20th	Day	30% 4 9% 23% 26% 7%	1921
	21st to end	Day	36% 4 8% 22% 23% 7%	1890
December	1st to 10th	Day	35% 3 6% 19% 26% 10%	3020
	11th to 20th	Day	45% 4 8% 16% 20% 7%	3460
	21st to end	Day	39% 4 9% 28% 17% 2	4565
January	1st to 10th	Night	32% 3 9% 21% 27% 7%	7636
	11th to 20th	Night	31% 4 4 14% 36% 11%	7680
	21st to end	Night	43% 3 5% 19% 22% 10%	8401
February	1st to 10th	Night	39% 4 10% 20% 21% 6%	2730
	11th to 20th	Night	44% 4 8% 16% 22% 6%	2467
	21st to end	Night	39% 5% 9% 17% 23% 7%	2037
March	1st to 10th	Night	40% 6% 7% 13% 26% 9%	5028
	11th to 20th	Night	28% 4 7% 15% 28% 18%	5090
	21st to end	Night	37% 5% 7% 23% 20% 8%	5588
April	1st to 10th	Night	35% 5% 11% 20% 23% 6%	2310
	11th to 20th	Night	30% 6% 9% 23% 23% 8%	2092
	21st to end	Night	35% 6% 12% 22% 21% 4	1932
May	1st to 10th	Night	42% 7% 14% 23% 12% 2	5264
	11th to 20th	Night	42% 8% 13% 24% 12% 2	5235
	21st to end	Night	45% 9% 13% 20% 11% 2	5771
June	1st to 10th	Night	40% 11% 16% 19% 12% 2	1890
	11th to 20th	Night	38% 11% 18% 22% 9% 2	1890
	21st to end	Night	34% 14% 16% 20% 13% 3	1890
July	1st to 10th	Night	42% 10% 20% 21% 6% 1	5235
	11th to 20th	Night	44% 14% 24% 13% 5% 1	5226
	21st to end	Night	50% 11% 16% 14% 6% 2	5606
August	1st to 10th	Night	57% 13% 15% 12% 4	4124
	11th to 20th	Night	38% 10% 25% 20% 6%	4122
	21st to end	Night	34% 9% 14% 28% 14% 1	4861
September	1st to 10th	Night	35% 9% 15% 19% 17% 5%	2299
	11th to 20th	Night	44% 8% 11% 16% 19% 2	2310
	21st to end	Night	44% 8% 13% 16% 16% 4	2289
October	1st to 10th	Night	36% 6% 8% 19% 25% 7%	3778
	11th to 20th	Night	23% 3 6% 19% 27% 22%	3899
	21st to end	Night	28% 3 5% 21% 27% 16%	4252
November	1st to 10th	Night	34% 4 7% 18% 26% 10%	2461
	11th to 20th	Night	33% 4 7% 18% 26% 12%	2693
	21st to end	Night	34% 5% 6% 22% 27% 7%	2730
December	1st to 10th	Night	36% 3 6% 20% 26% 9%	4380
	11th to 20th	Night	45% 4 9% 15% 18% 9%	4954
	21st to end	Night	38% 5% 12% 23% 21% 2	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	22% 17% 36% 21% 4	330
	11th to 20th	Day	22% 21% 32% 18% 5%	330
	21st to end	Day	23% 19% 36% 15% 6%	363
February	1st to 10th	Day	19% 18% 36% 20% 7% 1	330
	11th to 20th	Day	35% 16% 35% 12% 2	330
	21st to end	Day	28% 20% 31% 17% 4	310
March	1st to 10th	Day	22% 14% 29% 25% 8% 1	540
	11th to 20th	Day	20% 14% 38% 22% 7%	540
	21st to end	Day	20% 13% 36% 24% 6% 1	594
April	1st to 10th	Day	19% 14% 31% 21% 14% 1	540
	11th to 20th	Day	14% 14% 29% 25% 14% 3	532
	21st to end	Day	16% 8% 27% 26% 16% 6%	540
May	1st to 10th	Day	11% 12% 35% 24% 15% 4	543
	11th to 20th	Day	16% 5% 19% 28% 22% 9%	567
	21st to end	Day	17% 5% 15% 24% 26% 13%	617
June	1st to 10th	Day	12% 2 14% 32% 28% 11%	570
	11th to 20th	Day	9% 4 16% 27% 26% 18%	570
	21st to end	Day	8% 2 12% 29% 32% 16%	570
July	1st to 10th	Day	9% 2 8% 20% 33% 28%	565
	11th to 20th	Day	8% 2 7% 24% 36% 24%	564
	21st to end	Day	8% 2 8% 27% 36% 19%	620
August	1st to 10th	Day	17% 2 11% 25% 28% 17%	566
	11th to 20th	Day	12% 3 7% 25% 30% 23%	559
	21st to end	Day	11% 3 10% 23% 29% 24%	627
September	1st to 10th	Day	10% 2 11% 25% 29% 23%	570
	11th to 20th	Day	16% 4 10% 21% 31% 19%	570
	21st to end	Day	22% 4 19% 23% 25% 8%	562
October	1st to 10th	Day	16% 4 19% 28% 23% 11%	530
	11th to 20th	Day	13% 6% 23% 28% 23% 7%	530
	21st to end	Day	19% 5% 22% 28% 19% 6%	583
November	1st to 10th	Day	21% 7% 23% 30% 16% 4	535
	11th to 20th	Day	15% 11% 33% 29% 9% 2	361
	21st to end	Day	10% 13% 35% 26% 13% 2	330
December	1st to 10th	Day	25% 10% 35% 22% 6% 1	330
	11th to 20th	Day	22% 12% 31% 25% 9% 1	330
	21st to end	Day	26% 15% 30% 21% 8% 1	363
January	1st to 10th	Night	20% 12% 33% 28% 6%	840
	11th to 20th	Night	20% 11% 35% 29% 5%	840
	21st to end	Night	18% 9% 40% 30% 3	924
February	1st to 10th	Night	18% 9% 34% 35% 3	840
	11th to 20th	Night	23% 11% 41% 23% 2	823
	21st to end	Night	21% 13% 38% 25% 3	692
March	1st to 10th	Night	17% 12% 31% 36% 5%	840
	11th to 20th	Night	16% 11% 36% 29% 7% 1	840
	21st to end	Night	19% 10% 35% 29% 7%	924
April	1st to 10th	Night	16% 12% 32% 32% 8%	840
	11th to 20th	Night	13% 12% 30% 30% 15%	831
	21st to end	Night	13% 6% 28% 37% 16%	672
May	1st to 10th	Night	12% 7% 29% 35% 17%	630
	11th to 20th	Night	14% 5% 21% 36% 22% 1	621
	21st to end	Night	17% 4 13% 31% 32% 3	683
June	1st to 10th	Night	12% 3 13% 40% 30% 3	630
	11th to 20th	Night	12% 3 14% 31% 31% 9%	630
	21st to end	Night	8% 2 10% 37% 38% 5%	630
July	1st to 10th	Night	9% 3 8% 28% 43% 10%	615
	11th to 20th	Night	9% 2 6% 28% 45% 10%	612
	21st to end	Night	8% 2 9% 32% 42% 7%	690
August	1st to 10th	Night	17% 2 6% 29% 39% 7%	627
	11th to 20th	Night	13% 2 8% 27% 39% 9%	624
	21st to end	Night	11% 2 9% 26% 45% 7%	840
September	1st to 10th	Night	10% 2 8% 30% 42% 7%	840
	11th to 20th	Night	17% 3 12% 25% 37% 7%	840
	21st to end	Night	20% 3 14% 33% 27% 2	833
October	1st to 10th	Night	16% 4 17% 30% 28% 6%	800
	11th to 20th	Night	16% 5% 23% 33% 20% 2	800
	21st to end	Night	15% 6% 23% 33% 21% 3	880
November	1st to 10th	Night	15% 5% 23% 36% 18% 2	820
	11th to 20th	Night	13% 9% 30% 36% 11% 1	840
	21st to end	Night	14% 7% 30% 36% 13% 1	840
December	1st to 10th	Night	23% 9% 28% 34% 7%	840
	11th to 20th	Night	20% 8% 29% 34% 9% 1	840
	21st to end	Night	23% 9% 27% 32% 8%	924

Page generated at 2026-09-26 04:18:42. Version ac07

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