Mobile
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mobile 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	10% 5% 2 6% 4 5% 5% 4 7% 9% 43%	114261
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 45%	115010
Transparency	Day	35% 8% 13% 18% 18% 8%	118159
	Night	35% 7% 13% 17% 19% 9%	119252
Seeing	Day	11% 9% 20% 25% 23% 12%	15085
	Night	12% 7% 21% 30% 24% 7%	25057

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% 5% 2 5% 3 3 4 3 4 7% 50%	4406
	11th to 20th	Day	13% 6% 2 5% 4 4 3 3 5% 6% 51%	4520
	21st to end	Day	20% 7% 3 6% 4 4 4 3 5% 6% 37%	4972
February	1st to 10th	Day	16% 8% 3 6% 4 4 4 4 4 6% 42%	2000
	11th to 20th	Day	17% 5% 2 5% 3 4 4 3 5% 8% 43%	1948
	21st to end	Day	15% 6% 2 7% 6% 4 4 4 6% 7% 40%	1650
March	1st to 10th	Day	13% 8% 3 8% 4 4 4 4 5% 6% 40%	4480
	11th to 20th	Day	10% 5% 2 5% 4 3 4 3 6% 7% 51%	4692
	21st to end	Day	14% 7% 2 7% 4 4 4 3 4 6% 44%	5967
April	1st to 10th	Day	10% 7% 2 5% 4 4 4 4 6% 8% 46%	2400
	11th to 20th	Day	11% 5% 3 5% 4 4 5% 4 6% 8% 45%	2374
	21st to end	Day	6% 4 2 5% 3 3 4 4 6% 8% 54%	2400
May	1st to 10th	Day	8% 5% 2 5% 3 4 5% 5% 7% 10% 47%	3885
	11th to 20th	Day	13% 5% 2 6% 4 4 5% 4 6% 8% 43%	4046
	21st to end	Day	5% 3 2 5% 4 5% 5% 5% 8% 11% 48%	4541
June	1st to 10th	Day	7% 6% 2 7% 6% 5% 7% 6% 10% 11% 34%	2470
	11th to 20th	Day	4 4 2 6% 5% 6% 7% 7% 10% 10% 38%	2470
	21st to end	Day	7% 6% 2 7% 6% 7% 6% 7% 9% 12% 30%	2470
July	1st to 10th	Day	5% 5% 2 8% 7% 7% 8% 7% 10% 13% 26%	4091
	11th to 20th	Day	5% 4 2 8% 7% 7% 8% 6% 10% 13% 33%	3800
	21st to end	Day	5% 6% 3 8% 7% 8% 9% 7% 12% 14% 22%	4118
August	1st to 10th	Day	3 3 1 4 4 5% 7% 6% 10% 14% 43%	3785
	11th to 20th	Day	6% 3 2 6% 5% 5% 7% 6% 8% 11% 42%	3729
	21st to end	Day	6% 4 3 8% 6% 7% 8% 6% 8% 10% 34%	4180
September	1st to 10th	Day	10% 5% 2 6% 5% 5% 6% 5% 8% 10% 36%	2280
	11th to 20th	Day	10% 7% 2 7% 6% 4 6% 4 6% 9% 39%	2096
	21st to end	Day	7% 4 2 6% 4 4 5% 4 5% 7% 53%	2090
October	1st to 10th	Day	6% 4 2 5% 3 3 4 3 6% 8% 56%	2090
	11th to 20th	Day	8% 3 1 3 3 3 4 3 5% 8% 58%	2057
	21st to end	Day	9% 4 1 5% 4 4 3 4 5% 6% 54%	2090
November	1st to 10th	Day	8% 5% 1 5% 3 3 3 4 5% 7% 56%	1795
	11th to 20th	Day	11% 4 2 5% 3 3 3 3 4 6% 57%	1800
	21st to end	Day	10% 5% 2 6% 5% 4 4 3 5% 8% 49%	1800
December	1st to 10th	Day	14% 7% 2 6% 4 4 3 3 5% 6% 47%	2930
	11th to 20th	Day	9% 6% 2 6% 4 3 4 3 5% 5% 53%	3373
	21st to end	Day	15% 8% 3 6% 3 3 3 3 4 6% 45%	4466
January	1st to 10th	Night	14% 5% 2 5% 4 4 4 3 5% 6% 47%	5521
	11th to 20th	Night	17% 9% 3 6% 4 3 3 2 3 6% 46%	5440
	21st to end	Night	20% 7% 2 6% 4 4 4 3 5% 6% 39%	5984
February	1st to 10th	Night	14% 9% 2 6% 4 4 3 3 4 7% 44%	2400
	11th to 20th	Night	19% 7% 3 6% 4 3 4 3 5% 5% 42%	2338
	21st to end	Night	16% 8% 3 6% 4 4 4 4 5% 6% 40%	1980
March	1st to 10th	Night	20% 9% 3 7% 4 3 3 3 5% 6% 37%	5373
	11th to 20th	Night	13% 7% 2 6% 4 4 3 3 4 6% 47%	5293
	21st to end	Night	13% 7% 2 6% 4 4 4 3 5% 6% 47%	4962
April	1st to 10th	Night	13% 7% 2 6% 4 5% 4 3 6% 7% 44%	2000
	11th to 20th	Night	12% 5% 2 5% 3 4 4 4 5% 7% 49%	1975
	21st to end	Night	6% 4 2 3 4 2 4 3 5% 7% 61%	2000
May	1st to 10th	Night	9% 7% 2 7% 5% 4 4 4 6% 9% 43%	3230
	11th to 20th	Night	11% 6% 3 6% 5% 4 4 4 6% 7% 44%	3049
	21st to end	Night	4 4 2 4 4 4 4 4 8% 14% 48%	3130
June	1st to 10th	Night	7% 5% 2 6% 5% 4 5% 5% 9% 13% 40%	1710
	11th to 20th	Night	4 3 2 5% 5% 5% 5% 5% 9% 12% 47%	1710
	21st to end	Night	5% 5% 2 6% 5% 5% 7% 5% 10% 13% 37%	1710
July	1st to 10th	Night	4 5% 2 7% 6% 5% 7% 7% 10% 16% 32%	2862
	11th to 20th	Night	2 3 2 6% 5% 5% 6% 6% 8% 11% 46%	3160
	21st to end	Night	3 4 2 6% 6% 7% 7% 8% 12% 15% 30%	3435
August	1st to 10th	Night	2 2 1 4 4 4 5% 5% 9% 15% 49%	3144
	11th to 20th	Night	3 4 2 4 4 4 5% 5% 8% 13% 48%	3100
	21st to end	Night	5% 4 2 6% 5% 5% 6% 6% 8% 11% 41%	3476
September	1st to 10th	Night	8% 5% 2 6% 6% 5% 6% 6% 8% 12% 36%	1900
	11th to 20th	Night	10% 5% 2 7% 5% 5% 4 3 6% 9% 43%	2062
	21st to end	Night	7% 5% 2 5% 4 4 5% 4 7% 8% 50%	2090
October	1st to 10th	Night	7% 4 2 5% 4 4 3 3 6% 8% 55%	2090
	11th to 20th	Night	7% 3 1 3 2 3 4 3 5% 7% 62%	2118
	21st to end	Night	11% 4 2 4 3 3 3 2 4 6% 57%	2508
November	1st to 10th	Night	8% 5% 2 5% 4 4 3 3 5% 6% 55%	2498
	11th to 20th	Night	11% 5% 2 5% 3 3 3 2 4 6% 54%	2600
	21st to end	Night	10% 5% 2 5% 4 4 4 3 6% 7% 49%	2600
December	1st to 10th	Night	12% 5% 3 6% 4 3 4 4 6% 7% 47%	4250
	11th to 20th	Night	13% 5% 2 5% 3 4 4 3 5% 6% 50%	4822
	21st to end	Night	16% 8% 3 7% 4 3 3 2 4 4 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	34% 5% 6% 18% 28% 10%	4407
	11th to 20th	Day	34% 4 6% 17% 29% 10%	4520
	21st to end	Day	48% 5% 8% 13% 16% 11%	4972
February	1st to 10th	Day	43% 6% 7% 14% 19% 10%	2000
	11th to 20th	Day	39% 7% 8% 16% 20% 10%	1958
	21st to end	Day	41% 9% 9% 15% 16% 10%	1650
March	1st to 10th	Day	43% 7% 8% 16% 18% 9%	4480
	11th to 20th	Day	29% 8% 9% 17% 22% 16%	4692
	21st to end	Day	41% 6% 11% 17% 15% 10%	5969
April	1st to 10th	Day	35% 8% 11% 17% 19% 10%	2400
	11th to 20th	Day	34% 7% 11% 18% 20% 10%	2374
	21st to end	Day	27% 8% 12% 22% 22% 8%	2400
May	1st to 10th	Day	27% 12% 18% 24% 15% 5%	3920
	11th to 20th	Day	37% 9% 13% 22% 18% 1	4050
	21st to end	Day	27% 11% 17% 32% 12% 1	4554
June	1st to 10th	Day	38% 12% 18% 23% 8% 2	2470
	11th to 20th	Day	33% 13% 19% 22% 10% 3	2470
	21st to end	Day	40% 14% 21% 15% 9% 1	2470
July	1st to 10th	Day	43% 15% 28% 12% 3	4026
	11th to 20th	Day	41% 14% 34% 8% 2	3737
	21st to end	Day	45% 17% 22% 14% 2	3987
August	1st to 10th	Day	26% 12% 18% 25% 18% 2	3773
	11th to 20th	Day	33% 10% 19% 20% 17% 1	3765
	21st to end	Day	42% 11% 19% 15% 12% 2	4179
September	1st to 10th	Day	39% 13% 18% 14% 12% 4	2280
	11th to 20th	Day	40% 11% 14% 14% 14% 7%	2096
	21st to end	Day	31% 8% 11% 21% 20% 9%	2090
October	1st to 10th	Day	28% 5% 8% 12% 18% 30%	3480
	11th to 20th	Day	16% 4 7% 18% 22% 33%	3401
	21st to end	Day	21% 4 5% 13% 38% 19%	3428
November	1st to 10th	Day	28% 6% 9% 19% 24% 14%	1795
	11th to 20th	Day	30% 5% 8% 15% 27% 15%	1800
	21st to end	Day	33% 6% 9% 17% 21% 13%	1800
December	1st to 10th	Day	38% 4 8% 17% 23% 9%	2930
	11th to 20th	Day	32% 4 9% 24% 20% 10%	3370
	21st to end	Day	39% 5% 6% 17% 27% 4	4466
January	1st to 10th	Night	37% 5% 7% 15% 28% 8%	5521
	11th to 20th	Night	41% 3 5% 13% 30% 8%	5440
	21st to end	Night	47% 3 7% 13% 20% 9%	5984
February	1st to 10th	Night	41% 5% 6% 17% 21% 10%	2400
	11th to 20th	Night	44% 5% 5% 14% 20% 13%	2339
	21st to end	Night	43% 8% 9% 14% 13% 13%	1980
March	1st to 10th	Night	48% 5% 7% 14% 18% 7%	5373
	11th to 20th	Night	36% 7% 8% 14% 19% 16%	5293
	21st to end	Night	36% 6% 13% 20% 14% 11%	4962
April	1st to 10th	Night	38% 7% 12% 12% 21% 11%	2000
	11th to 20th	Night	34% 6% 11% 18% 21% 10%	1975
	21st to end	Night	24% 5% 13% 27% 24% 8%	2000
May	1st to 10th	Night	34% 11% 17% 17% 17% 4	3260
	11th to 20th	Night	36% 8% 14% 23% 16% 1	3050
	21st to end	Night	23% 11% 19% 32% 15% 1	3138
June	1st to 10th	Night	33% 11% 22% 23% 10% 2	1710
	11th to 20th	Night	27% 12% 22% 25% 13% 2	1710
	21st to end	Night	34% 12% 26% 18% 9% 1	1710
July	1st to 10th	Night	36% 14% 33% 13% 4	2817
	11th to 20th	Night	29% 14% 45% 10% 2 1	3100
	21st to end	Night	37% 21% 25% 15% 2	3325
August	1st to 10th	Night	20% 13% 24% 28% 14% 1	3132
	11th to 20th	Night	25% 12% 26% 24% 14%	3130
	21st to end	Night	36% 13% 21% 17% 11% 3	3476
September	1st to 10th	Night	36% 12% 20% 15% 11% 5%	1900
	11th to 20th	Night	37% 8% 16% 18% 14% 8%	2062
	21st to end	Night	29% 10% 14% 22% 17% 9%	2090
October	1st to 10th	Night	32% 6% 8% 12% 21% 21%	3480
	11th to 20th	Night	14% 3 6% 19% 25% 33%	3513
	21st to end	Night	19% 3 5% 11% 43% 19%	4120
November	1st to 10th	Night	30% 4 9% 16% 26% 15%	2498
	11th to 20th	Night	33% 3 6% 17% 27% 15%	2600
	21st to end	Night	33% 6% 8% 19% 22% 13%	2600
December	1st to 10th	Night	36% 4 8% 18% 23% 11%	4250
	11th to 20th	Night	34% 4 7% 23% 22% 9%	4824
	21st to end	Night	42% 5% 6% 18% 25% 5%	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	17% 20% 39% 18% 6%	300
	11th to 20th	Day	14% 20% 31% 24% 9% 2	300
	21st to end	Day	22% 20% 34% 20% 5% 1	330
February	1st to 10th	Day	21% 19% 35% 17% 7% 1	300
	11th to 20th	Day	24% 21% 31% 18% 5%	300
	21st to end	Day	11% 26% 43% 15% 5%	249
March	1st to 10th	Day	14% 24% 37% 19% 5%	300
	11th to 20th	Day	14% 24% 35% 20% 7%	333
	21st to end	Day	16% 14% 32% 27% 11% 1	550
April	1st to 10th	Day	16% 16% 31% 24% 12% 1	500
	11th to 20th	Day	13% 15% 32% 21% 16% 2	492
	21st to end	Day	7% 11% 30% 30% 19% 4	500
May	1st to 10th	Day	9% 9% 29% 26% 22% 5%	503
	11th to 20th	Day	7% 5% 22% 34% 23% 9%	527
	21st to end	Day	7% 2 15% 37% 22% 16%	549
June	1st to 10th	Day	9% 2 14% 31% 29% 15%	490
	11th to 20th	Day	7% 2 12% 29% 33% 18%	490
	21st to end	Day	9% 2 10% 22% 34% 22%	490
July	1st to 10th	Day	7% 2 7% 18% 35% 31%	485
	11th to 20th	Day	6% 2 4 16% 36% 37%	484
	21st to end	Day	6% 1 5% 20% 41% 26%	532
August	1st to 10th	Day	4 1 5% 19% 36% 36%	486
	11th to 20th	Day	8% 1 4 15% 36% 34%	479
	21st to end	Day	10% 2 7% 20% 36% 25%	539
September	1st to 10th	Day	10% 2 7% 20% 37% 23%	490
	11th to 20th	Day	13% 2 11% 26% 34% 14%	490
	21st to end	Day	8% 2 10% 32% 34% 14%	490
October	1st to 10th	Day	9% 4 16% 38% 25% 8%	490
	11th to 20th	Day	8% 6% 16% 31% 31% 8%	457
	21st to end	Day	14% 10% 18% 33% 20% 5%	330
November	1st to 10th	Day	14% 5% 23% 42% 15% 2	300
	11th to 20th	Day	16% 14% 26% 27% 13% 4	300
	21st to end	Day	11% 15% 32% 26% 13% 3	300
December	1st to 10th	Day	17% 13% 32% 25% 11% 2	300
	11th to 20th	Day	19% 16% 32% 23% 8% 1	300
	21st to end	Day	22% 14% 29% 20% 12% 2	330
January	1st to 10th	Night	17% 14% 34% 29% 6%	800
	11th to 20th	Night	17% 13% 28% 32% 9%	800
	21st to end	Night	21% 13% 32% 28% 5%	880
February	1st to 10th	Night	17% 12% 35% 29% 6%	800
	11th to 20th	Night	22% 13% 33% 24% 8%	783
	21st to end	Night	17% 15% 38% 25% 4	660
March	1st to 10th	Night	16% 13% 32% 32% 7%	800
	11th to 20th	Night	14% 12% 33% 30% 10% 1	779
	21st to end	Night	12% 8% 32% 36% 12%	660
April	1st to 10th	Night	16% 11% 26% 33% 14% 1	600
	11th to 20th	Night	14% 6% 31% 30% 18% 1	593
	21st to end	Night	8% 4 20% 43% 23% 2	600
May	1st to 10th	Night	10% 4 22% 40% 21% 3	600
	11th to 20th	Night	7% 3 17% 38% 32% 4	591
	21st to end	Night	6% 2 11% 34% 39% 8%	634
June	1st to 10th	Night	8% 2 8% 34% 40% 9%	570
	11th to 20th	Night	5% 2 4 31% 45% 14%	570
	21st to end	Night	8% 2 6% 24% 46% 15%	570
July	1st to 10th	Night	4 1 4 19% 51% 22%	555
	11th to 20th	Night	3 2 3 13% 46% 34%	552
	21st to end	Night	3 1 2 22% 49% 23%	624
August	1st to 10th	Night	3 2 13% 51% 31%	567
	11th to 20th	Night	7% 3 15% 47% 27%	564
	21st to end	Night	10% 2 6% 20% 44% 19%	627
September	1st to 10th	Night	9% 2 6% 21% 44% 18%	570
	11th to 20th	Night	11% 2 11% 25% 39% 11%	732
	21st to end	Night	9% 2 11% 28% 42% 8%	760
October	1st to 10th	Night	9% 3 18% 37% 29% 4	760
	11th to 20th	Night	8% 4 21% 32% 29% 5%	760
	21st to end	Night	12% 6% 21% 33% 25% 3	836
November	1st to 10th	Night	11% 5% 21% 43% 19% 2	780
	11th to 20th	Night	13% 9% 24% 37% 15% 2	800
	21st to end	Night	11% 10% 28% 35% 15% 1	800
December	1st to 10th	Night	14% 10% 29% 32% 13% 2	800
	11th to 20th	Night	19% 9% 29% 33% 11% 1	800
	21st to end	Night	22% 10% 32% 28% 8%	880

Page generated at 2025-05-23 08:21:01. Version ac07

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