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 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	9% 5% 2 6% 4 5% 5% 5% 7% 10% 42%	147758
	Night	10% 6% 2 6% 4 4 5% 4 6% 9% 44%	143655
Transparency	Day	35% 8% 16% 18% 16% 7%	151618
	Night	35% 7% 15% 18% 17% 8%	147871
Seeing	Day	11% 8% 20% 25% 23% 13%	16898
	Night	12% 7% 20% 30% 25% 7%	26735

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% 6% 2 6% 4 4 4 3 5% 7% 46%	5720
	11th to 20th	Day	11% 5% 2 4 4 4 3 3 5% 7% 52%	5880
	21st to end	Day	20% 7% 3 7% 4 4 4 3 5% 6% 36%	6436
February	1st to 10th	Day	15% 8% 3 6% 4 4 3 3 4 6% 44%	2100
	11th to 20th	Day	17% 5% 2 5% 3 4 5% 3 5% 8% 43%	2048
	21st to end	Day	15% 6% 2 7% 5% 4 5% 4 5% 7% 41%	1730
March	1st to 10th	Day	13% 8% 3 8% 4 4 4 4 5% 7% 40%	4580
	11th to 20th	Day	10% 5% 2 5% 4 3 4 3 6% 7% 52%	4796
	21st to end	Day	14% 7% 3 7% 4 4 4 3 5% 6% 45%	6099
April	1st to 10th	Day	11% 7% 2 5% 4 4 4 4 6% 8% 45%	2520
	11th to 20th	Day	10% 5% 3 5% 4 4 4 4 7% 8% 46%	2494
	21st to end	Day	6% 4 2 5% 4 3 4 4 6% 8% 53%	2520
May	1st to 10th	Day	16% 7% 2 6% 4 3 4 4 6% 9% 39%	7021
	11th to 20th	Day	9% 4 1 5% 4 4 5% 5% 7% 10% 46%	7328
	21st to end	Day	7% 5% 2 7% 5% 5% 6% 5% 9% 11% 38%	8391
June	1st to 10th	Day	7% 5% 2 6% 6% 5% 7% 6% 10% 11% 34%	2730
	11th to 20th	Day	5% 4 2 6% 5% 6% 7% 7% 10% 11% 37%	2730
	21st to end	Day	7% 5% 2 7% 6% 7% 7% 7% 10% 12% 31%	2730
July	1st to 10th	Day	3 3 2 6% 5% 6% 8% 7% 10% 15% 34%	7623
	11th to 20th	Day	3 3 2 7% 6% 6% 8% 6% 11% 15% 34%	7080
	21st to end	Day	4 4 2 7% 6% 6% 8% 7% 11% 16% 29%	7687
August	1st to 10th	Day	2 2 1 5% 4 5% 7% 6% 11% 15% 42%	5545
	11th to 20th	Day	4 3 1 5% 4 4 6% 5% 8% 14% 45%	5486
	21st to end	Day	6% 4 2 8% 6% 7% 8% 6% 8% 12% 33%	6080
September	1st to 10th	Day	9% 5% 2 6% 4 5% 6% 5% 8% 10% 38%	2520
	11th to 20th	Day	9% 6% 2 6% 6% 4 6% 4 6% 9% 42%	2316
	21st to end	Day	6% 4 2 5% 4 3 5% 4 6% 7% 53%	2288
October	1st to 10th	Day	7% 5% 2 5% 4 3 4 3 6% 8% 55%	2200
	11th to 20th	Day	8% 3 1 3 3 3 3 3 5% 8% 60%	2165
	21st to end	Day	9% 4 1 5% 4 4 3 4 5% 6% 54%	2200
November	1st to 10th	Day	8% 5% 1 5% 3 3 3 3 5% 7% 57%	1887
	11th to 20th	Day	10% 4 1 5% 3 3 3 3 4 6% 57%	1890
	21st to end	Day	10% 5% 2 6% 5% 4 4 3 5% 8% 49%	1890
December	1st to 10th	Day	14% 7% 3 6% 4 3 3 3 5% 6% 46%	3020
	11th to 20th	Day	9% 6% 2 6% 4 3 4 3 5% 5% 53%	3463
	21st to end	Day	15% 8% 3 6% 3 3 3 3 4 6% 45%	4565
January	1st to 10th	Night	13% 6% 2 6% 4 5% 5% 4 6% 7% 43%	7155
	11th to 20th	Night	15% 8% 3 6% 4 3 3 3 4 6% 47%	7080
	21st to end	Night	20% 8% 3 6% 5% 4 4 3 5% 6% 37%	7745
February	1st to 10th	Night	14% 8% 2 5% 4 4 3 3 4 7% 46%	2520
	11th to 20th	Night	19% 7% 3 6% 4 4 4 3 5% 5% 42%	2458
	21st to end	Night	16% 8% 3 6% 4 4 4 4 5% 6% 40%	2076
March	1st to 10th	Night	20% 9% 3 7% 4 3 3 3 5% 6% 37%	5493
	11th to 20th	Night	12% 7% 2 6% 4 4 3 3 4 6% 47%	5410
	21st to end	Night	13% 7% 2 6% 4 4 4 3 5% 6% 47%	5072
April	1st to 10th	Night	12% 7% 2 6% 4 5% 4 3 6% 7% 43%	2100
	11th to 20th	Night	11% 5% 2 5% 3 4 4 4 5% 7% 50%	2075
	21st to end	Night	6% 4 2 4 4 2 4 3 5% 7% 60%	2100
May	1st to 10th	Night	17% 8% 3 7% 4 4 4 3 5% 8% 37%	5832
	11th to 20th	Night	10% 5% 3 6% 4 4 4 4 7% 9% 45%	5514
	21st to end	Night	5% 5% 2 7% 6% 5% 6% 5% 8% 13% 38%	5761
June	1st to 10th	Night	7% 5% 2 6% 5% 4 6% 5% 9% 13% 39%	1890
	11th to 20th	Night	4 3 2 5% 4 5% 5% 5% 9% 12% 46%	1890
	21st to end	Night	5% 5% 2 6% 5% 5% 7% 6% 10% 13% 37%	1890
July	1st to 10th	Night	3 4 2 6% 5% 5% 6% 6% 10% 15% 38%	5328
	11th to 20th	Night	2 3 2 6% 5% 6% 7% 6% 9% 13% 42%	5877
	21st to end	Night	3 3 2 7% 6% 7% 8% 7% 11% 15% 31%	6389
August	1st to 10th	Night	2 2 1 5% 4 4 6% 5% 10% 14% 46%	4604
	11th to 20th	Night	2 3 2 4 4 4 5% 5% 8% 13% 50%	4560
	21st to end	Night	5% 4 2 7% 6% 6% 7% 6% 8% 11% 39%	5046
September	1st to 10th	Night	8% 5% 2 6% 5% 5% 6% 6% 8% 12% 38%	2100
	11th to 20th	Night	9% 5% 2 6% 5% 4 4 3 6% 9% 46%	2280
	21st to end	Night	7% 5% 2 5% 4 4 4 4 7% 8% 51%	2289
October	1st to 10th	Night	7% 4 2 5% 5% 5% 3 3 5% 8% 53%	2200
	11th to 20th	Night	7% 3 1 3 2 3 4 3 5% 6% 63%	2230
	21st to end	Night	11% 4 2 4 3 3 4 2 4 6% 57%	2640
November	1st to 10th	Night	8% 5% 2 5% 4 4 3 3 5% 6% 56%	2626
	11th to 20th	Night	11% 5% 2 5% 3 3 3 2 4 6% 55%	2730
	21st to end	Night	10% 5% 2 6% 4 4 4 3 6% 7% 49%	2730
December	1st to 10th	Night	13% 5% 3 6% 4 3 3 4 6% 7% 46%	4380
	11th to 20th	Night	12% 5% 2 5% 3 4 4 3 5% 6% 51%	4952
	21st to end	Night	16% 8% 3 7% 4 3 3 2 4 4 45%	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	38% 5% 10% 17% 24% 7%	5721
	11th to 20th	Day	32% 3 5% 19% 29% 11%	5880
	21st to end	Day	48% 4 7% 12% 16% 13%	6436
February	1st to 10th	Day	41% 6% 7% 14% 20% 11%	2100
	11th to 20th	Day	39% 7% 8% 17% 19% 10%	2058
	21st to end	Day	40% 8% 9% 15% 17% 10%	1730
March	1st to 10th	Day	42% 7% 9% 16% 17% 9%	4580
	11th to 20th	Day	28% 8% 9% 17% 22% 16%	4796
	21st to end	Day	41% 6% 11% 18% 16% 9%	6101
April	1st to 10th	Day	36% 8% 11% 18% 18% 10%	2520
	11th to 20th	Day	34% 7% 11% 18% 21% 9%	2494
	21st to end	Day	28% 8% 12% 22% 22% 8%	2520
May	1st to 10th	Day	39% 8% 16% 19% 13% 4	7056
	11th to 20th	Day	31% 7% 20% 25% 15% 2	7332
	21st to end	Day	37% 10% 18% 23% 10% 2	8405
June	1st to 10th	Day	38% 12% 18% 22% 9% 2	2730
	11th to 20th	Day	35% 12% 20% 20% 10% 3	2730
	21st to end	Day	39% 14% 22% 17% 8% 1	2730
July	1st to 10th	Day	34% 12% 33% 17% 4	7558
	11th to 20th	Day	36% 13% 38% 11% 1	7017
	21st to end	Day	37% 13% 27% 21% 1	7517
August	1st to 10th	Day	27% 10% 23% 22% 16% 2	5533
	11th to 20th	Day	27% 9% 29% 23% 12% 1	5522
	21st to end	Day	41% 9% 20% 18% 11% 1	6079
September	1st to 10th	Day	37% 12% 18% 16% 12% 4	2520
	11th to 20th	Day	38% 10% 13% 17% 15% 6%	2316
	21st to end	Day	30% 8% 13% 22% 19% 9%	2288
October	1st to 10th	Day	29% 5% 8% 12% 17% 29%	3590
	11th to 20th	Day	16% 4 6% 18% 23% 33%	3509
	21st to end	Day	21% 4 5% 13% 39% 19%	3538
November	1st to 10th	Day	27% 6% 9% 18% 24% 15%	1887
	11th to 20th	Day	29% 5% 8% 16% 28% 15%	1890
	21st to end	Day	33% 6% 10% 18% 21% 12%	1890
December	1st to 10th	Day	39% 4 8% 16% 23% 9%	3020
	11th to 20th	Day	32% 4 9% 24% 21% 10%	3460
	21st to end	Day	39% 5% 6% 17% 27% 4	4565
January	1st to 10th	Night	40% 4 11% 13% 24% 7%	7156
	11th to 20th	Night	40% 3 5% 15% 27% 11%	7080
	21st to end	Night	50% 3 7% 13% 19% 9%	7745
February	1st to 10th	Night	40% 5% 6% 17% 22% 10%	2520
	11th to 20th	Night	44% 5% 6% 13% 19% 12%	2459
	21st to end	Night	42% 8% 9% 15% 13% 13%	2076
March	1st to 10th	Night	48% 5% 8% 14% 18% 7%	5493
	11th to 20th	Night	36% 7% 8% 14% 20% 16%	5410
	21st to end	Night	36% 6% 13% 20% 14% 11%	5072
April	1st to 10th	Night	39% 7% 12% 12% 21% 10%	2100
	11th to 20th	Night	33% 6% 10% 19% 22% 9%	2075
	21st to end	Night	25% 5% 13% 27% 23% 7%	2100
May	1st to 10th	Night	44% 7% 16% 14% 13% 5%	5862
	11th to 20th	Night	34% 7% 19% 23% 15% 2	5515
	21st to end	Night	34% 11% 21% 24% 9% 1	5771
June	1st to 10th	Night	34% 10% 22% 22% 10% 2	1890
	11th to 20th	Night	28% 12% 24% 23% 12% 1	1890
	21st to end	Night	34% 12% 26% 19% 8% 1	1890
July	1st to 10th	Night	31% 11% 36% 17% 4	5285
	11th to 20th	Night	31% 15% 42% 11% 1	5820
	21st to end	Night	36% 16% 26% 21% 1	6245
August	1st to 10th	Night	23% 12% 29% 23% 12% 2	4592
	11th to 20th	Night	23% 9% 33% 25% 9%	4590
	21st to end	Night	37% 11% 23% 18% 10% 2	5046
September	1st to 10th	Night	34% 12% 21% 17% 11% 5%	2100
	11th to 20th	Night	34% 8% 16% 20% 15% 7%	2280
	21st to end	Night	28% 10% 15% 23% 16% 8%	2289
October	1st to 10th	Night	33% 6% 8% 12% 21% 21%	3590
	11th to 20th	Night	14% 3 6% 19% 25% 33%	3625
	21st to end	Night	19% 3 5% 12% 42% 19%	4252
November	1st to 10th	Night	29% 4 8% 17% 26% 16%	2626
	11th to 20th	Night	32% 4 6% 18% 26% 15%	2730
	21st to end	Night	33% 6% 9% 19% 22% 12%	2730
December	1st to 10th	Night	37% 4 8% 18% 23% 10%	4380
	11th to 20th	Night	34% 4 7% 22% 22% 10%	4954
	21st to end	Night	42% 5% 6% 18% 25% 5%	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% 19% 38% 18% 8%	330
	11th to 20th	Day	13% 20% 32% 25% 8% 2	330
	21st to end	Day	22% 20% 33% 20% 4 1	363
February	1st to 10th	Day	19% 18% 37% 17% 7% 1	330
	11th to 20th	Day	22% 22% 32% 19% 6%	330
	21st to end	Day	10% 27% 41% 15% 5%	273
March	1st to 10th	Day	14% 22% 36% 22% 6%	330
	11th to 20th	Day	13% 24% 34% 20% 8% 1	365
	21st to end	Day	15% 13% 30% 28% 12% 1	594
April	1st to 10th	Day	16% 15% 30% 26% 12% 1	540
	11th to 20th	Day	12% 15% 32% 22% 17% 2	532
	21st to end	Day	6% 11% 30% 30% 19% 4	540
May	1st to 10th	Day	10% 9% 28% 26% 22% 5%	543
	11th to 20th	Day	7% 5% 22% 34% 23% 9%	567
	21st to end	Day	8% 3 17% 36% 22% 15%	617
June	1st to 10th	Day	9% 2 13% 32% 30% 14%	570
	11th to 20th	Day	8% 3 11% 28% 33% 18%	570
	21st to end	Day	8% 2 9% 21% 34% 25%	570
July	1st to 10th	Day	6% 2 7% 18% 36% 33%	565
	11th to 20th	Day	6% 2 4 16% 35% 37%	564
	21st to end	Day	6% 1 5% 20% 40% 27%	620
August	1st to 10th	Day	4 1 4 18% 36% 36%	566
	11th to 20th	Day	8% 1 4 15% 35% 38%	559
	21st to end	Day	9% 2 6% 20% 36% 26%	627
September	1st to 10th	Day	9% 2 6% 22% 37% 24%	570
	11th to 20th	Day	11% 2 9% 25% 35% 18%	570
	21st to end	Day	7% 2 9% 31% 35% 15%	562
October	1st to 10th	Day	10% 4 16% 38% 25% 7%	530
	11th to 20th	Day	7% 6% 16% 31% 32% 8%	495
	21st to end	Day	14% 10% 19% 32% 20% 5%	363
November	1st to 10th	Day	12% 6% 22% 41% 15% 3	330
	11th to 20th	Day	15% 13% 25% 28% 14% 5%	330
	21st to end	Day	10% 15% 33% 26% 13% 2	330
December	1st to 10th	Day	20% 13% 32% 23% 11% 2	330
	11th to 20th	Day	18% 15% 31% 24% 10% 2	330
	21st to end	Day	20% 15% 28% 21% 13% 3	363
January	1st to 10th	Night	17% 14% 34% 29% 6%	840
	11th to 20th	Night	17% 13% 28% 32% 9%	840
	21st to end	Night	21% 13% 32% 29% 5%	924
February	1st to 10th	Night	17% 13% 35% 29% 6%	840
	11th to 20th	Night	22% 12% 33% 24% 8%	823
	21st to end	Night	17% 15% 38% 25% 4	692
March	1st to 10th	Night	16% 13% 31% 32% 8%	840
	11th to 20th	Night	14% 12% 32% 31% 10% 1	818
	21st to end	Night	11% 8% 31% 36% 14%	693
April	1st to 10th	Night	15% 11% 26% 33% 14% 1	630
	11th to 20th	Night	13% 6% 30% 31% 18% 1	623
	21st to end	Night	8% 5% 20% 43% 23% 1	630
May	1st to 10th	Night	11% 4 22% 40% 20% 2	630
	11th to 20th	Night	7% 3 16% 39% 32% 3	621
	21st to end	Night	7% 2 11% 34% 39% 7%	683
June	1st to 10th	Night	9% 2 7% 34% 39% 8%	630
	11th to 20th	Night	5% 2 5% 29% 46% 13%	630
	21st to end	Night	7% 2 5% 23% 47% 16%	630
July	1st to 10th	Night	3 1 3 18% 52% 22%	615
	11th to 20th	Night	3 2 2 13% 48% 33%	612
	21st to end	Night	3 1 2 23% 48% 23%	690
August	1st to 10th	Night	3 1 2 12% 52% 30%	627
	11th to 20th	Night	7% 3 14% 47% 29%	624
	21st to end	Night	10% 2 5% 20% 45% 19%	693
September	1st to 10th	Night	8% 2 6% 23% 44% 17%	630
	11th to 20th	Night	10% 2 10% 25% 40% 12%	810
	21st to end	Night	9% 2 10% 30% 42% 7%	833
October	1st to 10th	Night	9% 4 18% 37% 29% 4	800
	11th to 20th	Night	8% 4 20% 32% 30% 6%	800
	21st to end	Night	12% 6% 21% 33% 25% 3	880
November	1st to 10th	Night	11% 5% 20% 43% 20% 2	820
	11th to 20th	Night	12% 9% 23% 38% 17% 1	840
	21st to end	Night	11% 9% 28% 35% 14% 1	840
December	1st to 10th	Night	15% 10% 29% 32% 13% 1	840
	11th to 20th	Night	18% 8% 28% 33% 12% 1	840
	21st to end	Night	22% 10% 31% 28% 9%	924

Page generated at 2026-09-26 03:18:42. Version ac07

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