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 2025-05-26.

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% 44%	114610
	Night	14% 6% 2 5% 4 4 4 3 5% 7% 45%	114664
Transparency	Day	37% 7% 11% 20% 19% 6%	118313
	Night	37% 6% 10% 19% 21% 7%	119100
Seeing	Day	16% 8% 22% 24% 19% 10%	15954
	Night	16% 7% 24% 31% 20% 3	26087

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	14% 6% 1 4 3 2 2 2 3 5% 56%	4056
	11th to 20th	Day	12% 6% 2 4 3 3 3 2 3 3 59%	4060
	21st to end	Day	18% 6% 2 5% 4 4 4 3 4 5% 45%	4466
February	1st to 10th	Day	15% 7% 2 4 4 4 4 4 7% 7% 43%	1800
	11th to 20th	Day	22% 6% 2 4 3 3 2 3 4 5% 45%	1937
	21st to end	Day	18% 8% 3 6% 4 4 4 3 4 6% 42%	1685
March	1st to 10th	Day	20% 7% 2 6% 3 3 3 3 4 6% 41%	4935
	11th to 20th	Day	9% 5% 2 6% 3 3 3 2 4 7% 55%	4980
	21st to end	Day	17% 7% 2 6% 4 3 3 3 4 5% 47%	5465
April	1st to 10th	Day	11% 5% 1 5% 3 4 4 4 6% 8% 50%	2200
	11th to 20th	Day	13% 5% 2 5% 4 3 4 4 5% 7% 49%	2355
	21st to end	Day	13% 5% 2 6% 4 4 4 4 5% 7% 47%	2575
May	1st to 10th	Day	11% 7% 2 7% 5% 6% 5% 5% 7% 10% 36%	4212
	11th to 20th	Day	16% 7% 3 7% 5% 4 4 3 5% 8% 36%	4211
	21st to end	Day	7% 4 2 6% 4 4 5% 4 6% 10% 48%	4541
June	1st to 10th	Day	9% 6% 3 7% 4 5% 5% 5% 8% 11% 38%	2470
	11th to 20th	Day	7% 5% 2 6% 5% 5% 6% 5% 8% 9% 43%	2470
	21st to end	Day	6% 5% 2 6% 5% 5% 6% 5% 9% 12% 39%	2470
July	1st to 10th	Day	8% 5% 2 7% 5% 5% 6% 5% 9% 11% 36%	4120
	11th to 20th	Day	7% 6% 2 6% 5% 6% 7% 5% 8% 12% 36%	4120
	21st to end	Day	11% 8% 4 9% 6% 6% 6% 5% 9% 11% 26%	4466
August	1st to 10th	Day	19% 6% 2 6% 5% 6% 5% 5% 8% 10% 27%	4104
	11th to 20th	Day	9% 5% 2 6% 5% 6% 6% 4 8% 11% 37%	4044
	21st to end	Day	6% 4 1 5% 3 4 5% 4 6% 9% 54%	4261
September	1st to 10th	Day	8% 5% 2 5% 4 5% 6% 5% 7% 9% 43%	2095
	11th to 20th	Day	14% 6% 2 6% 4 4 4 5% 6% 8% 42%	2090
	21st to end	Day	18% 6% 2 6% 4 4 4 4 5% 5% 41%	2090
October	1st to 10th	Day	14% 5% 2 4 3 3 3 2 4 5% 56%	1986
	11th to 20th	Day	13% 5% 1 4 3 3 3 2 3 6% 58%	1900
	21st to end	Day	14% 5% 2 4 3 3 2 2 4 4 58%	2090
November	1st to 10th	Day	13% 6% 2 5% 3 2 3 2 4 5% 54%	1957
	11th to 20th	Day	13% 5% 2 4 3 3 3 3 5% 6% 53%	1830
	21st to end	Day	15% 5% 2 5% 4 3 4 3 5% 5% 51%	1800
December	1st to 10th	Day	14% 5% 2 4 3 3 3 2 4 5% 54%	2930
	11th to 20th	Day	19% 7% 3 6% 4 4 4 3 5% 6% 41%	3373
	21st to end	Day	21% 6% 2 4 3 3 3 3 4 6% 45%	4466
January	1st to 10th	Night	13% 5% 2 4 3 3 3 2 3 4 58%	5889
	11th to 20th	Night	12% 6% 2 4 3 3 3 3 3 5% 56%	5900
	21st to end	Night	18% 7% 2 4 3 3 3 3 4 6% 48%	6490
February	1st to 10th	Night	15% 6% 2 5% 4 4 4 3 5% 6% 46%	2600
	11th to 20th	Night	21% 7% 2 5% 4 3 3 3 4 4 43%	2346
	21st to end	Night	15% 6% 2 5% 4 3 4 4 5% 7% 45%	1943
March	1st to 10th	Night	19% 6% 2 6% 4 3 3 3 4 5% 45%	4918
	11th to 20th	Night	9% 4 2 4 3 3 4 3 5% 7% 55%	4980
	21st to end	Night	16% 4 2 5% 4 4 4 3 5% 6% 48%	5467
April	1st to 10th	Night	12% 5% 2 5% 4 4 4 3 6% 7% 48%	2200
	11th to 20th	Night	12% 5% 2 5% 3 4 3 3 5% 7% 52%	1991
	21st to end	Night	12% 5% 2 5% 5% 5% 4 4 5% 7% 47%	1840
May	1st to 10th	Night	14% 7% 3 6% 5% 4 4 4 6% 8% 41%	2903
	11th to 20th	Night	17% 7% 2 6% 5% 5% 4 3 6% 8% 37%	2902
	21st to end	Night	8% 5% 2 6% 4 4 5% 5% 8% 11% 42%	3130
June	1st to 10th	Night	10% 6% 2 7% 5% 6% 6% 5% 7% 11% 35%	1710
	11th to 20th	Night	9% 6% 2 7% 6% 6% 5% 5% 7% 10% 37%	1710
	21st to end	Night	7% 5% 3 6% 6% 6% 6% 5% 9% 12% 36%	1710
July	1st to 10th	Night	9% 7% 3 9% 6% 6% 6% 5% 7% 10% 31%	2840
	11th to 20th	Night	8% 6% 3 5% 4 4 6% 5% 10% 13% 34%	2840
	21st to end	Night	13% 9% 4 9% 7% 6% 7% 6% 8% 9% 22%	3087
August	1st to 10th	Night	20% 10% 3 7% 5% 4 5% 4 7% 8% 24%	2825
	11th to 20th	Night	10% 8% 3 8% 6% 6% 6% 5% 8% 9% 31%	2785
	21st to end	Night	5% 4 2 6% 5% 5% 5% 5% 7% 10% 48%	3348
September	1st to 10th	Night	9% 6% 2 6% 4 4 5% 4 7% 9% 43%	2080
	11th to 20th	Night	16% 7% 3 7% 5% 4 5% 4 5% 7% 37%	2090
	21st to end	Night	17% 7% 2 7% 4 4 4 4 5% 6% 40%	2090
October	1st to 10th	Night	15% 5% 1 5% 3 4 4 2 4 5% 51%	2194
	11th to 20th	Night	14% 5% 2 4 3 3 3 3 4 5% 54%	2280
	21st to end	Night	13% 4 2 5% 3 3 3 2 3 5% 58%	2508
November	1st to 10th	Night	14% 5% 2 5% 4 3 3 2 4 6% 53%	2341
	11th to 20th	Night	13% 5% 2 5% 4 3 3 3 5% 5% 52%	2565
	21st to end	Night	13% 4 1 4 4 3 5% 3 5% 7% 50%	2600
December	1st to 10th	Night	15% 6% 2 4 3 3 3 2 4 5% 52%	4250
	11th to 20th	Night	20% 7% 2 5% 4 3 3 3 4 5% 43%	4822
	21st to end	Night	20% 4 2 4 3 3 3 3 4 6% 46%	6490

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 5% 20% 32% 7%	4057
	11th to 20th	Day	32% 3 4 15% 36% 10%	4060
	21st to end	Day	41% 4 5% 18% 23% 9%	4466
February	1st to 10th	Day	38% 5% 11% 22% 19% 5%	1800
	11th to 20th	Day	42% 5% 8% 19% 21% 6%	1947
	21st to end	Day	45% 4 7% 16% 21% 7%	1685
March	1st to 10th	Day	44% 5% 6% 14% 19% 13%	4935
	11th to 20th	Day	30% 5% 7% 15% 25% 19%	4980
	21st to end	Day	40% 4 6% 23% 21% 5%	5465
April	1st to 10th	Day	31% 6% 11% 21% 24% 6%	2200
	11th to 20th	Day	34% 5% 10% 21% 21% 9%	2355
	21st to end	Day	35% 6% 13% 24% 19% 4	2575
May	1st to 10th	Day	40% 11% 16% 19% 12% 2	4250
	11th to 20th	Day	44% 9% 12% 20% 14% 1	4215
	21st to end	Day	29% 10% 17% 23% 19% 4	4554
June	1st to 10th	Day	37% 10% 15% 26% 11% 1	2470
	11th to 20th	Day	33% 11% 18% 23% 14% 1	2470
	21st to end	Day	34% 11% 19% 21% 14% 2	2470
July	1st to 10th	Day	37% 12% 19% 20% 10% 2	4055
	11th to 20th	Day	37% 13% 26% 19% 5%	4051
	21st to end	Day	49% 13% 15% 17% 6% 1	4324
August	1st to 10th	Day	48% 10% 18% 19% 5%	4091
	11th to 20th	Day	37% 10% 20% 19% 11% 2	4083
	21st to end	Day	26% 8% 15% 35% 14% 2	4261
September	1st to 10th	Day	33% 11% 14% 20% 18% 3	2095
	11th to 20th	Day	38% 8% 15% 17% 19% 3	2090
	21st to end	Day	44% 7% 9% 19% 17% 4	2090
October	1st to 10th	Day	29% 4 6% 21% 29% 10%	3298
	11th to 20th	Day	20% 3 5% 19% 29% 24%	3140
	21st to end	Day	27% 3 5% 25% 24% 16%	3428
November	1st to 10th	Day	34% 5% 7% 19% 28% 8%	1957
	11th to 20th	Day	32% 4 9% 22% 26% 7%	1830
	21st to end	Day	36% 4 8% 22% 24% 7%	1800
December	1st to 10th	Day	34% 3 6% 20% 27% 10%	2930
	11th to 20th	Day	45% 4 8% 16% 20% 6%	3370
	21st to end	Day	40% 4 9% 28% 17% 2	4466
January	1st to 10th	Night	30% 4 5% 17% 35% 9%	5889
	11th to 20th	Night	31% 5% 5% 15% 36% 8%	5900
	21st to end	Night	39% 3 5% 18% 25% 9%	6490
February	1st to 10th	Night	39% 4 10% 20% 21% 6%	2600
	11th to 20th	Night	44% 4 8% 16% 22% 6%	2347
	21st to end	Night	38% 6% 10% 17% 23% 7%	1943
March	1st to 10th	Night	40% 6% 6% 12% 27% 9%	4918
	11th to 20th	Night	28% 4 7% 15% 28% 19%	4980
	21st to end	Night	37% 5% 7% 23% 20% 8%	5467
April	1st to 10th	Night	35% 5% 10% 20% 23% 6%	2200
	11th to 20th	Night	31% 6% 9% 22% 23% 9%	1991
	21st to end	Night	36% 6% 12% 22% 20% 4	1840
May	1st to 10th	Night	40% 9% 14% 21% 14% 2	2930
	11th to 20th	Night	44% 9% 12% 21% 14% 1	2903
	21st to end	Night	29% 12% 17% 27% 14% 1	3138
June	1st to 10th	Night	40% 11% 16% 19% 12% 2	1710
	11th to 20th	Night	38% 11% 17% 22% 10% 2	1710
	21st to end	Night	36% 14% 16% 18% 12% 4	1710
July	1st to 10th	Night	46% 12% 17% 15% 9% 2	2795
	11th to 20th	Night	35% 14% 26% 20% 3 1	2786
	21st to end	Night	54% 13% 15% 13% 4 1	2988
August	1st to 10th	Night	54% 10% 17% 14% 5%	2814
	11th to 20th	Night	43% 11% 22% 14% 8% 1	2812
	21st to end	Night	29% 9% 14% 27% 19% 2	3348
September	1st to 10th	Night	36% 10% 15% 18% 16% 5%	2080
	11th to 20th	Night	44% 9% 11% 15% 19% 2	2090
	21st to end	Night	43% 8% 12% 16% 16% 4	2090
October	1st to 10th	Night	36% 6% 8% 19% 25% 7%	3662
	11th to 20th	Night	22% 3 6% 19% 27% 23%	3779
	21st to end	Night	28% 4 5% 21% 27% 16%	4120
November	1st to 10th	Night	35% 4 8% 18% 25% 11%	2341
	11th to 20th	Night	34% 4 7% 18% 26% 11%	2565
	21st to end	Night	34% 5% 6% 22% 27% 7%	2600
December	1st to 10th	Night	36% 4 6% 20% 26% 9%	4250
	11th to 20th	Night	45% 4 9% 15% 18% 9%	4824
	21st to end	Night	38% 5% 12% 22% 21% 2	6490

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	20% 18% 36% 22% 4	300
	11th to 20th	Day	23% 20% 32% 20% 6%	300
	21st to end	Day	22% 18% 37% 16% 7%	330
February	1st to 10th	Day	19% 18% 35% 20% 7% 1	300
	11th to 20th	Day	35% 16% 34% 12% 3	300
	21st to end	Day	26% 20% 32% 18% 4	284
March	1st to 10th	Day	22% 15% 29% 24% 8% 1	500
	11th to 20th	Day	19% 13% 39% 21% 7%	500
	21st to end	Day	21% 14% 35% 23% 6% 1	550
April	1st to 10th	Day	20% 14% 32% 20% 12% 1	500
	11th to 20th	Day	14% 14% 29% 25% 14% 4	492
	21st to end	Day	17% 8% 27% 26% 17% 5%	500
May	1st to 10th	Day	10% 11% 34% 24% 16% 4	503
	11th to 20th	Day	17% 5% 20% 27% 22% 9%	527
	21st to end	Day	14% 4 15% 24% 28% 15%	549
June	1st to 10th	Day	12% 2 13% 34% 28% 11%	490
	11th to 20th	Day	10% 3 14% 26% 27% 19%	490
	21st to end	Day	9% 2 12% 30% 31% 17%	490
July	1st to 10th	Day	10% 2 7% 20% 32% 28%	485
	11th to 20th	Day	8% 1 7% 25% 35% 24%	484
	21st to end	Day	7% 2 8% 29% 35% 19%	532
August	1st to 10th	Day	14% 2 12% 25% 29% 18%	486
	11th to 20th	Day	12% 3 8% 27% 29% 21%	479
	21st to end	Day	11% 2 10% 21% 29% 26%	539
September	1st to 10th	Day	11% 2 11% 23% 31% 22%	490
	11th to 20th	Day	17% 4 11% 21% 29% 18%	490
	21st to end	Day	22% 3 20% 22% 25% 8%	490
October	1st to 10th	Day	17% 4 19% 27% 22% 12%	490
	11th to 20th	Day	13% 6% 23% 28% 23% 7%	490
	21st to end	Day	18% 5% 21% 29% 21% 6%	539
November	1st to 10th	Day	21% 6% 22% 30% 17% 4	495
	11th to 20th	Day	16% 10% 33% 29% 10% 2	330
	21st to end	Day	10% 11% 36% 26% 14% 3	300
December	1st to 10th	Day	24% 10% 36% 22% 7% 1	300
	11th to 20th	Day	22% 11% 31% 26% 9% 1	300
	21st to end	Day	27% 13% 31% 20% 8% 1	330
January	1st to 10th	Night	20% 13% 33% 28% 6%	800
	11th to 20th	Night	20% 11% 35% 29% 5%	800
	21st to end	Night	18% 9% 40% 30% 3	880
February	1st to 10th	Night	18% 9% 35% 34% 4	800
	11th to 20th	Night	24% 11% 40% 23% 2	783
	21st to end	Night	20% 13% 38% 26% 3	660
March	1st to 10th	Night	17% 12% 31% 35% 5%	800
	11th to 20th	Night	16% 11% 36% 29% 8% 1	800
	21st to end	Night	20% 9% 36% 28% 7%	880
April	1st to 10th	Night	17% 12% 33% 31% 8%	800
	11th to 20th	Night	13% 13% 30% 29% 15%	791
	21st to end	Night	13% 6% 27% 36% 17%	640
May	1st to 10th	Night	12% 7% 28% 35% 18%	600
	11th to 20th	Night	14% 5% 21% 36% 22% 2	591
	21st to end	Night	15% 3 13% 32% 34% 3	634
June	1st to 10th	Night	12% 2 12% 40% 30% 4	570
	11th to 20th	Night	12% 3 14% 30% 32% 10%	570
	21st to end	Night	9% 2 10% 36% 38% 6%	570
July	1st to 10th	Night	9% 3 8% 28% 42% 10%	555
	11th to 20th	Night	8% 2 7% 28% 46% 9%	552
	21st to end	Night	7% 1 9% 33% 42% 7%	624
August	1st to 10th	Night	14% 2 6% 29% 41% 8%	567
	11th to 20th	Night	13% 2 9% 28% 40% 8%	564
	21st to end	Night	11% 1 9% 24% 48% 7%	760
September	1st to 10th	Night	11% 2 9% 29% 43% 7%	760
	11th to 20th	Night	18% 3 13% 23% 36% 7%	760
	21st to end	Night	20% 3 15% 32% 28% 2	760
October	1st to 10th	Night	17% 4 17% 30% 27% 6%	760
	11th to 20th	Night	16% 5% 23% 33% 21% 3	760
	21st to end	Night	14% 6% 22% 34% 21% 3	836
November	1st to 10th	Night	16% 5% 23% 36% 19% 2	780
	11th to 20th	Night	14% 8% 30% 36% 11% 1	800
	21st to end	Night	14% 7% 30% 35% 14% 1	800
December	1st to 10th	Night	23% 9% 28% 33% 8%	800
	11th to 20th	Night	20% 7% 28% 35% 9% 1	800
	21st to end	Night	24% 8% 27% 32% 9%	880

Page generated at 2025-05-23 09:20:59. Version ac07

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