Dallas(GA)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dallas(GA) clear sky chart from 2005-11-06 to 2025-07-21.

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% 7% 3 6% 5% 5% 5% 4 6% 7% 41%	120169
	Night	13% 7% 2 6% 4 4 4 4 5% 7% 44%	118962
Transparency	Day	40% 5% 10% 20% 19% 5%	123998
	Night	38% 5% 9% 20% 21% 6%	123269
Seeing	Day	17% 10% 23% 23% 17% 9%	15714
	Night	16% 10% 23% 27% 20% 4	25725

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	16% 10% 4 4 3 3 3 3 4 4 46%	4056
	11th to 20th	Day	10% 8% 4 5% 3 3 3 3 3 6% 52%	4060
	21st to end	Day	20% 11% 3 6% 4 3 3 2 4 6% 38%	4761
February	1st to 10th	Day	16% 9% 2 6% 4 4 5% 3 5% 6% 39%	2000
	11th to 20th	Day	20% 8% 3 6% 3 4 3 3 4 5% 40%	1948
	21st to end	Day	19% 8% 3 6% 4 3 4 4 4 5% 41%	1650
March	1st to 10th	Day	20% 9% 3 7% 5% 4 4 3 5% 5% 34%	4543
	11th to 20th	Day	10% 7% 2 6% 4 4 3 3 6% 6% 49%	4980
	21st to end	Day	14% 6% 3 8% 4 4 4 3 4 5% 43%	5465
April	1st to 10th	Day	11% 7% 2 6% 4 5% 4 4 5% 6% 44%	2315
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 3 5% 6% 48%	2374
	21st to end	Day	11% 4 1 5% 5% 4 5% 4 6% 7% 48%	2518
May	1st to 10th	Day	13% 7% 3 7% 5% 5% 5% 4 6% 9% 35%	5862
	11th to 20th	Day	17% 8% 3 8% 5% 6% 6% 5% 7% 8% 28%	5861
	21st to end	Day	13% 7% 2 6% 5% 4 5% 4 6% 8% 40%	6433
June	1st to 10th	Day	10% 7% 2 8% 6% 6% 6% 5% 7% 8% 34%	2600
	11th to 20th	Day	5% 4 2 5% 5% 6% 8% 6% 8% 11% 42%	2600
	21st to end	Day	7% 5% 2 7% 6% 6% 6% 6% 8% 10% 38%	2600
July	1st to 10th	Day	7% 6% 2 8% 8% 8% 8% 7% 9% 11% 26%	4250
	11th to 20th	Day	7% 5% 3 7% 7% 7% 7% 5% 8% 10% 32%	4250
	21st to end	Day	10% 9% 3 11% 9% 8% 8% 6% 8% 9% 19%	4466
August	1st to 10th	Day	5% 5% 2 6% 5% 5% 7% 6% 9% 12% 39%	4056
	11th to 20th	Day	7% 5% 2 5% 5% 6% 5% 4 7% 11% 43%	3729
	21st to end	Day	8% 5% 2 5% 5% 5% 6% 5% 6% 7% 48%	4180
September	1st to 10th	Day	12% 6% 2 6% 4 5% 5% 5% 7% 9% 39%	2128
	11th to 20th	Day	17% 6% 2 6% 4 4 4 3 6% 7% 40%	2090
	21st to end	Day	13% 6% 2 5% 4 3 4 4 4 6% 47%	2090
October	1st to 10th	Day	12% 5% 2 4 3 4 3 3 5% 5% 54%	2090
	11th to 20th	Day	11% 6% 1 4 3 3 3 2 4 7% 55%	2021
	21st to end	Day	14% 5% 2 5% 3 3 3 3 4 5% 55%	2062
November	1st to 10th	Day	13% 6% 2 5% 4 3 2 3 4 4 54%	1762
	11th to 20th	Day	13% 5% 2 5% 4 3 4 3 5% 5% 52%	1800
	21st to end	Day	13% 7% 2 5% 4 4 3 4 5% 7% 46%	1800
December	1st to 10th	Day	15% 8% 2 6% 3 3 4 3 4 6% 45%	2930
	11th to 20th	Day	15% 9% 3 7% 5% 4 4 3 4 5% 40%	3373
	21st to end	Day	20% 7% 3 5% 3 4 4 3 5% 6% 40%	4466
January	1st to 10th	Night	15% 9% 3 6% 3 3 3 3 4 5% 46%	5889
	11th to 20th	Night	12% 9% 3 6% 4 3 3 3 4 5% 48%	5900
	21st to end	Night	17% 11% 3 6% 3 3 3 3 4 4 44%	6191
February	1st to 10th	Night	14% 8% 3 6% 5% 5% 3 4 4 6% 43%	2400
	11th to 20th	Night	22% 8% 2 5% 4 3 4 3 4 5% 40%	2338
	21st to end	Night	18% 8% 2 6% 4 3 4 3 6% 6% 41%	1980
March	1st to 10th	Night	20% 11% 3 6% 4 4 5% 4 5% 6% 33%	5309
	11th to 20th	Night	10% 6% 1 5% 4 4 3 4 6% 7% 51%	4980
	21st to end	Night	13% 7% 2 6% 4 4 4 3 5% 6% 45%	5467
April	1st to 10th	Night	11% 4 2 5% 4 5% 5% 4 6% 7% 46%	2100
	11th to 20th	Night	13% 5% 2 4 4 3 4 3 5% 7% 50%	1975
	21st to end	Night	8% 6% 2 5% 4 4 4 4 5% 7% 51%	1880
May	1st to 10th	Night	10% 7% 2 7% 6% 5% 6% 4 7% 10% 36%	4033
	11th to 20th	Night	16% 8% 2 7% 6% 5% 5% 5% 6% 8% 31%	4032
	21st to end	Night	11% 5% 2 6% 4 4 5% 4 7% 10% 42%	4421
June	1st to 10th	Night	5% 6% 2 6% 5% 5% 5% 5% 9% 11% 39%	1800
	11th to 20th	Night	4 3 1 4 5% 4 5% 5% 7% 12% 47%	1800
	21st to end	Night	6% 4 1 5% 5% 4 5% 5% 8% 13% 44%	1800
July	1st to 10th	Night	8% 6% 3 9% 7% 6% 6% 5% 8% 11% 32%	2930
	11th to 20th	Night	6% 5% 2 6% 5% 7% 6% 5% 9% 12% 36%	2930
	21st to end	Night	9% 10% 4 10% 6% 6% 7% 5% 8% 10% 24%	3087
August	1st to 10th	Night	6% 4 2 6% 5% 4 5% 4 8% 12% 43%	2855
	11th to 20th	Night	7% 5% 2 6% 5% 4 4 4 6% 9% 49%	3100
	21st to end	Night	9% 4 1 5% 3 3 4 4 6% 8% 52%	3476
September	1st to 10th	Night	9% 5% 2 6% 6% 5% 3 4 7% 8% 43%	2033
	11th to 20th	Night	13% 6% 2 6% 5% 4 4 3 5% 7% 44%	2090
	21st to end	Night	12% 4 2 5% 4 4 4 3 5% 6% 51%	2090
October	1st to 10th	Night	10% 6% 2 4 3 3 3 2 4 6% 59%	2090
	11th to 20th	Night	10% 6% 2 5% 3 3 3 3 4 5% 58%	2156
	21st to end	Night	12% 5% 1 4 3 3 3 3 4 4 57%	2532
November	1st to 10th	Night	12% 6% 2 4 3 3 3 3 4 5% 54%	2536
	11th to 20th	Night	12% 6% 2 5% 3 3 3 3 4 6% 53%	2600
	21st to end	Night	13% 6% 2 5% 4 4 4 3 5% 6% 48%	2600
December	1st to 10th	Night	16% 6% 2 5% 4 3 3 3 5% 5% 49%	4250
	11th to 20th	Night	16% 9% 2 6% 3 4 3 3 4 5% 45%	4822
	21st to end	Night	19% 8% 3 6% 4 4 4 3 5% 6% 39%	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	42% 2 5% 23% 23% 4	4057
	11th to 20th	Day	35% 3 5% 22% 29% 6%	4060
	21st to end	Day	50% 2 4 15% 22% 6%	4761
February	1st to 10th	Day	46% 3 7% 20% 21% 4	2000
	11th to 20th	Day	47% 3 6% 19% 19% 6%	1958
	21st to end	Day	46% 3 7% 15% 21% 8%	1650
March	1st to 10th	Day	52% 3 7% 11% 19% 8%	4543
	11th to 20th	Day	36% 3 6% 14% 24% 17%	4980
	21st to end	Day	43% 4 7% 21% 21% 4	5465
April	1st to 10th	Day	39% 4 10% 21% 20% 6%	2315
	11th to 20th	Day	37% 4 6% 20% 25% 8%	2374
	21st to end	Day	34% 5% 10% 26% 22% 3	2518
May	1st to 10th	Day	43% 7% 14% 20% 15% 1	5897
	11th to 20th	Day	50% 8% 15% 18% 9% 1	5865
	21st to end	Day	41% 5% 10% 24% 17% 2	6447
June	1st to 10th	Day	45% 6% 14% 21% 11% 2	2600
	11th to 20th	Day	32% 8% 19% 25% 14% 2	2600
	21st to end	Day	37% 8% 17% 23% 12% 2	2600
July	1st to 10th	Day	44% 12% 20% 18% 5% 1	4185
	11th to 20th	Day	41% 13% 19% 21% 5% 1	4181
	21st to end	Day	57% 11% 14% 13% 5%	4324
August	1st to 10th	Day	33% 8% 14% 33% 12%	4043
	11th to 20th	Day	33% 6% 17% 27% 14% 3	3765
	21st to end	Day	33% 7% 13% 23% 21% 3	4179
September	1st to 10th	Day	39% 7% 15% 17% 17% 5%	2128
	11th to 20th	Day	42% 6% 10% 20% 20% 2	2090
	21st to end	Day	38% 4 10% 19% 23% 6%	2090
October	1st to 10th	Day	26% 2 6% 13% 38% 14%	3480
	11th to 20th	Day	21% 3 4 16% 29% 27%	3339
	21st to end	Day	26% 3 5% 22% 32% 12%	3376
November	1st to 10th	Day	35% 2 7% 16% 30% 10%	1762
	11th to 20th	Day	34% 4 5% 18% 29% 10%	1800
	21st to end	Day	37% 4 7% 19% 26% 7%	1800
December	1st to 10th	Day	41% 2 5% 19% 27% 6%	2930
	11th to 20th	Day	48% 3 7% 18% 19% 5%	3370
	21st to end	Day	44% 4 7% 25% 19% 2	4466
January	1st to 10th	Night	41% 3 5% 21% 26% 4	5889
	11th to 20th	Night	40% 3 4 19% 27% 7%	5900
	21st to end	Night	45% 3 4 15% 28% 5%	6191
February	1st to 10th	Night	43% 3 7% 20% 19% 8%	2400
	11th to 20th	Night	47% 3 6% 17% 20% 7%	2339
	21st to end	Night	44% 4 7% 17% 19% 10%	1980
March	1st to 10th	Night	52% 3 7% 14% 18% 6%	5309
	11th to 20th	Night	32% 4 8% 15% 25% 16%	4980
	21st to end	Night	40% 4 6% 22% 21% 7%	5467
April	1st to 10th	Night	35% 4 10% 20% 22% 7%	2100
	11th to 20th	Night	34% 4 7% 21% 25% 9%	1975
	21st to end	Night	32% 5% 10% 28% 20% 5%	1880
May	1st to 10th	Night	41% 8% 15% 21% 13% 2	4060
	11th to 20th	Night	49% 7% 15% 21% 8%	4033
	21st to end	Night	35% 7% 14% 25% 17% 2	4429
June	1st to 10th	Night	36% 8% 19% 22% 14% 1	1800
	11th to 20th	Night	28% 7% 23% 25% 15% 2	1800
	21st to end	Night	30% 8% 22% 21% 15% 4	1800
July	1st to 10th	Night	44% 10% 19% 20% 7% 1	2885
	11th to 20th	Night	36% 12% 22% 21% 7% 1	2876
	21st to end	Night	52% 12% 15% 15% 5% 1	2988
August	1st to 10th	Night	31% 7% 16% 35% 10% 1	2844
	11th to 20th	Night	32% 6% 15% 30% 16% 1	3130
	21st to end	Night	29% 7% 14% 19% 28% 3	3476
September	1st to 10th	Night	36% 7% 15% 19% 16% 6%	2033
	11th to 20th	Night	39% 6% 11% 22% 19% 3	2090
	21st to end	Night	34% 4 12% 21% 22% 8%	2090
October	1st to 10th	Night	24% 3 7% 15% 38% 14%	3480
	11th to 20th	Night	18% 2 4 17% 32% 26%	3577
	21st to end	Night	23% 3 3 23% 31% 17%	4168
November	1st to 10th	Night	33% 3 8% 18% 26% 12%	2536
	11th to 20th	Night	33% 3 5% 19% 28% 11%	2600
	21st to end	Night	38% 3 6% 19% 27% 7%	2600
December	1st to 10th	Night	38% 3 5% 21% 27% 6%	4250
	11th to 20th	Night	43% 3 8% 16% 24% 5%	4824
	21st to end	Night	45% 4 6% 26% 17% 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	27% 27% 34% 9% 2	300
	11th to 20th	Day	29% 23% 32% 10% 5% 1	300
	21st to end	Day	25% 26% 35% 10% 2 1	330
February	1st to 10th	Day	25% 22% 36% 14% 3	300
	11th to 20th	Day	37% 18% 33% 11% 1	300
	21st to end	Day	27% 24% 37% 9% 3	249
March	1st to 10th	Day	30% 20% 31% 15% 3 1	324
	11th to 20th	Day	26% 18% 32% 17% 6% 1	500
	21st to end	Day	22% 18% 37% 18% 4 1	550
April	1st to 10th	Day	19% 20% 32% 19% 9% 1	500
	11th to 20th	Day	13% 17% 35% 23% 10% 2	492
	21st to end	Day	16% 10% 32% 26% 14% 2	500
May	1st to 10th	Day	15% 11% 32% 26% 13% 4	503
	11th to 20th	Day	15% 5% 25% 30% 17% 8%	527
	21st to end	Day	16% 6% 20% 30% 17% 11%	573
June	1st to 10th	Day	13% 3 21% 28% 25% 11%	530
	11th to 20th	Day	6% 3 17% 29% 26% 19%	530
	21st to end	Day	10% 2 15% 30% 28% 16%	530
July	1st to 10th	Day	9% 3 7% 29% 30% 22%	525
	11th to 20th	Day	8% 1 7% 22% 35% 28%	524
	21st to end	Day	8% 2 7% 25% 36% 21%	532
August	1st to 10th	Day	12% 2 11% 26% 28% 21%	486
	11th to 20th	Day	13% 2 8% 31% 28% 18%	479
	21st to end	Day	17% 1 8% 27% 28% 19%	539
September	1st to 10th	Day	16% 2 11% 26% 29% 17%	490
	11th to 20th	Day	20% 2 12% 27% 26% 12%	490
	21st to end	Day	16% 3 18% 25% 28% 10%	490
October	1st to 10th	Day	14% 3 23% 33% 18% 8%	490
	11th to 20th	Day	15% 10% 24% 27% 19% 4	490
	21st to end	Day	18% 10% 24% 26% 18% 3	511
November	1st to 10th	Day	22% 10% 28% 24% 13% 3	300
	11th to 20th	Day	18% 18% 36% 19% 8% 1	300
	21st to end	Day	14% 18% 41% 19% 8% 1	300
December	1st to 10th	Day	26% 23% 31% 16% 4	300
	11th to 20th	Day	26% 17% 31% 21% 4 1	300
	21st to end	Day	29% 16% 33% 17% 5% 1	330
January	1st to 10th	Night	25% 23% 28% 19% 5%	800
	11th to 20th	Night	23% 19% 29% 23% 6%	800
	21st to end	Night	20% 20% 34% 22% 3	880
February	1st to 10th	Night	20% 15% 34% 27% 5%	800
	11th to 20th	Night	27% 20% 31% 21% 1	783
	21st to end	Night	25% 19% 35% 18% 3	660
March	1st to 10th	Night	19% 19% 32% 25% 5%	800
	11th to 20th	Night	18% 15% 35% 23% 9% 1	800
	21st to end	Night	18% 17% 31% 26% 8%	880
April	1st to 10th	Night	15% 15% 33% 24% 12% 1	700
	11th to 20th	Night	18% 13% 30% 26% 11% 1	593
	21st to end	Night	11% 10% 25% 37% 15% 2	600
May	1st to 10th	Night	12% 8% 25% 34% 19% 2	600
	11th to 20th	Night	14% 5% 23% 30% 24% 4	591
	21st to end	Night	13% 2 15% 32% 31% 6%	650
June	1st to 10th	Night	9% 1 16% 36% 32% 7%	600
	11th to 20th	Night	5% 2 15% 30% 35% 14%	600
	21st to end	Night	8% 10% 34% 42% 7%	600
July	1st to 10th	Night	10% 2 8% 25% 42% 14%	585
	11th to 20th	Night	8% 1 4 24% 46% 17%	582
	21st to end	Night	8% 1 6% 29% 45% 11%	624
August	1st to 10th	Night	10% 4 32% 41% 13%	567
	11th to 20th	Night	9% 2 7% 32% 40% 10%	564
	21st to end	Night	17% 1 6% 27% 39% 11%	627
September	1st to 10th	Night	11% 1 10% 26% 39% 13%	703
	11th to 20th	Night	17% 2 10% 29% 36% 5%	760
	21st to end	Night	16% 2 14% 33% 32% 3	760
October	1st to 10th	Night	13% 3 22% 31% 24% 6%	760
	11th to 20th	Night	12% 9% 25% 30% 22% 3	760
	21st to end	Night	15% 9% 22% 33% 18% 3	836
November	1st to 10th	Night	16% 7% 25% 30% 20% 2	780
	11th to 20th	Night	17% 13% 28% 29% 12% 1	800
	21st to end	Night	18% 14% 29% 28% 11% 1	800
December	1st to 10th	Night	22% 16% 29% 24% 9% 1	800
	11th to 20th	Night	23% 14% 29% 26% 8% 1	800
	21st to end	Night	27% 14% 28% 25% 6%	880

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