Phenix City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Phenix City clear sky chart from 2005-11-06 to 2026-08-15.

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	11% 6% 2 6% 4 4 5% 4 6% 9% 42%	143407
	Night	12% 6% 2 6% 4 4 4 4 6% 8% 43%	138499
Transparency	Day	38% 7% 13% 18% 17% 6%	147244
	Night	37% 6% 12% 18% 19% 8%	142733
Seeing	Day	14% 8% 22% 25% 21% 11%	17175
	Night	14% 6% 22% 31% 23% 4	27123

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% 9% 3 8% 4 4 3 3 4 5% 44%	5258
	11th to 20th	Day	11% 6% 2 4 3 3 3 3 4 6% 54%	5280
	21st to end	Day	21% 8% 3 8% 4 3 3 3 4 5% 37%	6390
February	1st to 10th	Day	14% 8% 2 7% 5% 5% 5% 4 4 6% 40%	2100
	11th to 20th	Day	19% 8% 2 5% 3 3 4 3 5% 5% 42%	2048
	21st to end	Day	14% 7% 3 6% 4 5% 4 4 5% 6% 41%	1730
March	1st to 10th	Day	18% 8% 3 6% 4 4 4 4 5% 6% 37%	4643
	11th to 20th	Day	9% 6% 2 5% 4 4 4 4 5% 7% 52%	5090
	21st to end	Day	15% 6% 2 6% 4 4 4 3 5% 7% 44%	5586
April	1st to 10th	Day	11% 5% 3 5% 5% 3 5% 3 5% 7% 46%	2422
	11th to 20th	Day	10% 5% 1 4 4 3 4 4 5% 7% 50%	2494
	21st to end	Day	7% 4 2 6% 4 4 5% 4 5% 7% 52%	2590
May	1st to 10th	Day	14% 7% 3 7% 5% 4 5% 4 6% 8% 38%	7616
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 5% 7% 10% 38%	7626
	21st to end	Day	11% 7% 3 7% 5% 5% 6% 4 7% 10% 35%	8391
June	1st to 10th	Day	9% 6% 2 7% 6% 5% 7% 5% 8% 11% 32%	2730
	11th to 20th	Day	7% 4 1 6% 5% 5% 6% 5% 9% 12% 40%	2730
	21st to end	Day	6% 6% 2 6% 6% 6% 7% 6% 8% 12% 36%	2730
July	1st to 10th	Day	6% 4 2 6% 5% 5% 7% 6% 10% 15% 35%	7680
	11th to 20th	Day	5% 5% 2 7% 5% 5% 7% 6% 9% 14% 36%	7680
	21st to end	Day	6% 5% 2 8% 6% 7% 8% 7% 11% 16% 26%	8340
August	1st to 10th	Day	7% 4 2 6% 4 6% 6% 6% 10% 13% 37%	4166
	11th to 20th	Day	7% 4 2 5% 4 5% 5% 4 7% 9% 48%	3897
	21st to end	Day	7% 4 2 5% 4 4 5% 5% 7% 11% 46%	4312
September	1st to 10th	Day	9% 6% 2 8% 6% 5% 6% 5% 6% 8% 39%	2232
	11th to 20th	Day	15% 6% 2 6% 4 4 5% 4 6% 8% 41%	2200
	21st to end	Day	11% 5% 2 7% 5% 4 4 3 5% 6% 48%	2200
October	1st to 10th	Day	12% 5% 2 6% 3 3 3 3 5% 7% 52%	2200
	11th to 20th	Day	10% 3 1 4 3 3 3 2 5% 8% 58%	2163
	21st to end	Day	10% 6% 2 5% 3 3 4 2 4 6% 56%	2200
November	1st to 10th	Day	11% 5% 2 5% 4 3 3 4 4 5% 53%	1855
	11th to 20th	Day	13% 5% 2 4 2 3 2 3 4 6% 57%	1890
	21st to end	Day	13% 5% 2 5% 4 4 5% 3 4 7% 47%	1890
December	1st to 10th	Day	17% 5% 2 4 3 3 3 2 5% 5% 49%	3020
	11th to 20th	Day	14% 8% 2 6% 3 3 3 3 4 6% 47%	3463
	21st to end	Day	20% 7% 2 6% 3 3 4 3 4 5% 43%	4565
January	1st to 10th	Night	15% 6% 3 6% 4 4 4 3 5% 6% 44%	7635
	11th to 20th	Night	13% 7% 3 6% 4 4 4 3 4 5% 47%	7680
	21st to end	Night	18% 9% 3 6% 4 3 4 3 4 6% 39%	7787
February	1st to 10th	Night	14% 7% 3 7% 5% 4 3 3 5% 6% 46%	2520
	11th to 20th	Night	20% 7% 2 5% 3 3 3 3 4 5% 44%	2458
	21st to end	Night	15% 7% 2 6% 5% 4 4 3 5% 5% 44%	2076
March	1st to 10th	Night	19% 8% 2 7% 5% 4 4 3 5% 6% 37%	5429
	11th to 20th	Night	11% 5% 2 5% 4 4 4 4 5% 6% 50%	5090
	21st to end	Night	12% 5% 2 6% 5% 4 4 3 5% 6% 47%	5588
April	1st to 10th	Night	10% 6% 2 5% 5% 4 5% 4 7% 6% 47%	2214
	11th to 20th	Night	11% 4 3 5% 3 3 3 3 5% 8% 52%	2075
	21st to end	Night	8% 4 1 5% 4 4 4 3 6% 8% 53%	2027
May	1st to 10th	Night	15% 6% 2 6% 4 4 4 4 6% 9% 40%	5237
	11th to 20th	Night	13% 7% 2 7% 4 4 5% 4 7% 9% 38%	5234
	21st to end	Night	11% 6% 3 8% 5% 5% 5% 4 7% 10% 36%	5761
June	1st to 10th	Night	8% 7% 2 7% 6% 6% 8% 5% 8% 8% 35%	1890
	11th to 20th	Night	4 4 2 5% 4 6% 5% 6% 9% 12% 43%	1890
	21st to end	Night	5% 5% 2 6% 5% 5% 5% 6% 9% 13% 38%	1890
July	1st to 10th	Night	7% 6% 3 7% 6% 6% 7% 6% 10% 14% 28%	5278
	11th to 20th	Night	6% 5% 2 7% 6% 6% 8% 6% 10% 13% 30%	5277
	21st to end	Night	7% 6% 3 9% 6% 6% 7% 6% 10% 14% 27%	5736
August	1st to 10th	Night	6% 5% 2 8% 6% 5% 7% 6% 8% 14% 33%	3198
	11th to 20th	Night	5% 4 2 5% 5% 4 6% 5% 8% 12% 45%	3240
	21st to end	Night	7% 5% 2 5% 3 4 4 4 6% 9% 49%	3586
September	1st to 10th	Night	9% 5% 2 6% 5% 5% 6% 4 7% 11% 39%	2145
	11th to 20th	Night	12% 7% 3 6% 4 4 5% 4 6% 7% 43%	2200
	21st to end	Night	9% 5% 2 7% 4 5% 5% 3 5% 8% 48%	2200
October	1st to 10th	Night	9% 5% 2 5% 3 3 4 3 5% 6% 54%	2200
	11th to 20th	Night	9% 5% 2 4 3 3 3 3 4 5% 60%	2235
	21st to end	Night	11% 5% 1 5% 4 2 3 3 4 5% 59%	2640
November	1st to 10th	Night	11% 4 2 6% 3 3 3 3 4 5% 57%	2658
	11th to 20th	Night	13% 5% 2 4 4 2 3 2 4 5% 57%	2730
	21st to end	Night	13% 6% 2 5% 4 4 3 3 5% 6% 49%	2730
December	1st to 10th	Night	14% 7% 2 5% 3 3 3 2 3 5% 52%	4380
	11th to 20th	Night	16% 5% 2 5% 4 3 3 2 5% 6% 49%	4952
	21st to end	Night	20% 7% 2 6% 3 4 3 3 5% 6% 42%	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	43% 4 6% 20% 23% 5%	5259
	11th to 20th	Day	31% 3 5% 17% 33% 11%	5280
	21st to end	Day	51% 3 7% 10% 19% 10%	6390
February	1st to 10th	Day	44% 5% 7% 16% 21% 7%	2100
	11th to 20th	Day	44% 4 5% 17% 22% 8%	2058
	21st to end	Day	42% 6% 7% 15% 19% 10%	1730
March	1st to 10th	Day	46% 6% 8% 13% 20% 7%	4643
	11th to 20th	Day	32% 6% 7% 13% 22% 20%	5090
	21st to end	Day	40% 5% 10% 17% 18% 10%	5586
April	1st to 10th	Day	36% 6% 10% 22% 16% 9%	2422
	11th to 20th	Day	33% 5% 9% 18% 25% 10%	2494
	21st to end	Day	30% 7% 10% 23% 25% 5%	2590
May	1st to 10th	Day	43% 7% 12% 19% 17% 3	7651
	11th to 20th	Day	39% 7% 19% 22% 12% 2	7630
	21st to end	Day	42% 10% 15% 17% 15% 1	8405
June	1st to 10th	Day	40% 12% 16% 19% 11% 2	2730
	11th to 20th	Day	33% 11% 19% 22% 13% 2	2730
	21st to end	Day	36% 13% 18% 20% 10% 3	2730
July	1st to 10th	Day	36% 11% 31% 18% 3 1	7615
	11th to 20th	Day	38% 13% 29% 17% 2	7611
	21st to end	Day	43% 12% 24% 16% 4	8156
August	1st to 10th	Day	33% 11% 17% 29% 11%	4153
	11th to 20th	Day	31% 9% 14% 29% 15% 1	3933
	21st to end	Day	30% 10% 19% 25% 15% 2	4311
September	1st to 10th	Day	40% 10% 14% 17% 15% 4	2232
	11th to 20th	Day	39% 8% 12% 18% 18% 4	2200
	21st to end	Day	36% 6% 9% 22% 20% 7%	2200
October	1st to 10th	Day	29% 4 7% 13% 26% 21%	3590
	11th to 20th	Day	16% 3 5% 16% 27% 34%	3507
	21st to end	Day	21% 3 5% 17% 41% 13%	3538
November	1st to 10th	Day	34% 4 7% 14% 27% 14%	1855
	11th to 20th	Day	30% 3 8% 17% 27% 15%	1890
	21st to end	Day	36% 6% 8% 17% 24% 9%	1890
December	1st to 10th	Day	38% 4 6% 18% 26% 8%	3020
	11th to 20th	Day	40% 4 9% 19% 21% 8%	3460
	21st to end	Day	43% 4 6% 21% 22% 3	4565
January	1st to 10th	Night	40% 5% 7% 20% 23% 5%	7636
	11th to 20th	Night	39% 4 6% 17% 24% 10%	7680
	21st to end	Night	47% 3 5% 16% 21% 8%	7787
February	1st to 10th	Night	40% 4 7% 18% 20% 11%	2520
	11th to 20th	Night	43% 5% 6% 14% 22% 11%	2459
	21st to end	Night	40% 6% 8% 15% 16% 14%	2076
March	1st to 10th	Night	46% 6% 8% 14% 16% 10%	5429
	11th to 20th	Night	33% 6% 8% 12% 22% 19%	5090
	21st to end	Night	36% 5% 8% 18% 22% 11%	5588
April	1st to 10th	Night	36% 6% 11% 16% 19% 11%	2214
	11th to 20th	Night	30% 5% 7% 22% 25% 11%	2075
	21st to end	Night	29% 5% 11% 23% 23% 8%	2027
May	1st to 10th	Night	39% 8% 16% 17% 15% 5%	5264
	11th to 20th	Night	40% 7% 17% 22% 12% 2	5235
	21st to end	Night	41% 9% 15% 20% 14% 2	5771
June	1st to 10th	Night	41% 11% 16% 16% 14% 2	1890
	11th to 20th	Night	28% 11% 20% 25% 13% 2	1890
	21st to end	Night	33% 13% 18% 20% 12% 4	1890
July	1st to 10th	Night	41% 11% 27% 17% 3 1	5235
	11th to 20th	Night	40% 14% 29% 14% 3	5226
	21st to end	Night	43% 10% 25% 17% 4	5606
August	1st to 10th	Night	37% 11% 17% 25% 10% 1	3187
	11th to 20th	Night	28% 10% 18% 29% 13% 2	3270
	21st to end	Night	30% 8% 17% 25% 17% 2	3586
September	1st to 10th	Night	36% 10% 17% 18% 14% 5%	2145
	11th to 20th	Night	37% 9% 11% 19% 17% 5%	2200
	21st to end	Night	35% 7% 9% 20% 21% 7%	2200
October	1st to 10th	Night	33% 5% 8% 13% 24% 17%	3590
	11th to 20th	Night	16% 3 4 13% 30% 33%	3630
	21st to end	Night	20% 3 4 19% 35% 20%	4252
November	1st to 10th	Night	30% 4 9% 15% 27% 15%	2658
	11th to 20th	Night	31% 3 6% 17% 28% 15%	2730
	21st to end	Night	36% 5% 8% 17% 24% 11%	2730
December	1st to 10th	Night	36% 3 6% 20% 26% 8%	4380
	11th to 20th	Night	37% 4 10% 19% 23% 7%	4954
	21st to end	Night	42% 5% 6% 21% 23% 3	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	21% 20% 38% 17% 5%	330
	11th to 20th	Day	18% 25% 32% 16% 6% 2	330
	21st to end	Day	22% 22% 39% 12% 4 1	363
February	1st to 10th	Day	20% 20% 38% 16% 6%	330
	11th to 20th	Day	29% 18% 35% 15% 3	330
	21st to end	Day	19% 24% 37% 18% 2	273
March	1st to 10th	Day	20% 16% 33% 22% 7% 1	354
	11th to 20th	Day	18% 15% 34% 24% 8% 1	540
	21st to end	Day	17% 12% 36% 26% 8% 1	594
April	1st to 10th	Day	16% 16% 29% 26% 12% 1	540
	11th to 20th	Day	13% 13% 31% 25% 16% 3	532
	21st to end	Day	10% 9% 24% 35% 18% 4	540
May	1st to 10th	Day	12% 8% 28% 29% 19% 4	543
	11th to 20th	Day	12% 2 23% 30% 24% 9%	567
	21st to end	Day	14% 4 16% 29% 26% 12%	617
June	1st to 10th	Day	11% 4 14% 31% 27% 14%	570
	11th to 20th	Day	7% 3 14% 24% 28% 24%	570
	21st to end	Day	6% 3 13% 26% 29% 23%	570
July	1st to 10th	Day	7% 2 4 23% 35% 28%	565
	11th to 20th	Day	6% 1 5% 19% 35% 33%	564
	21st to end	Day	6% 1 7% 20% 40% 26%	620
August	1st to 10th	Day	11% 2 8% 23% 30% 25%	566
	11th to 20th	Day	8% 2 6% 18% 38% 27%	535
	21st to end	Day	13% 3 8% 27% 30% 20%	583
September	1st to 10th	Day	9% 3 12% 25% 35% 15%	530
	11th to 20th	Day	16% 3 10% 26% 33% 12%	530
	21st to end	Day	12% 3 12% 29% 33% 12%	530
October	1st to 10th	Day	14% 4 25% 32% 18% 7%	530
	11th to 20th	Day	9% 7% 20% 35% 23% 6%	530
	21st to end	Day	16% 7% 24% 28% 20% 4	583
November	1st to 10th	Day	20% 8% 25% 28% 15% 5%	333
	11th to 20th	Day	15% 10% 37% 26% 11% 2	330
	21st to end	Day	13% 16% 35% 25% 10% 1	330
December	1st to 10th	Day	25% 15% 35% 19% 6% 1	330
	11th to 20th	Day	25% 15% 31% 22% 6% 1	330
	21st to end	Day	26% 12% 29% 25% 7% 1	363
January	1st to 10th	Night	20% 13% 33% 27% 6%	840
	11th to 20th	Night	18% 11% 32% 30% 8%	840
	21st to end	Night	21% 10% 37% 28% 3	924
February	1st to 10th	Night	17% 10% 31% 35% 7%	840
	11th to 20th	Night	24% 8% 35% 29% 4	823
	21st to end	Night	18% 13% 37% 27% 5%	692
March	1st to 10th	Night	13% 12% 32% 36% 6%	840
	11th to 20th	Night	16% 9% 33% 31% 10% 1	840
	21st to end	Night	13% 11% 31% 33% 12%	924
April	1st to 10th	Night	13% 7% 31% 33% 16%	744
	11th to 20th	Night	13% 8% 24% 35% 18% 1	623
	21st to end	Night	9% 5% 24% 37% 25% 1	630
May	1st to 10th	Night	10% 4 23% 36% 24% 2	630
	11th to 20th	Night	12% 3 19% 35% 26% 5%	621
	21st to end	Night	11% 2 11% 32% 38% 6%	683
June	1st to 10th	Night	10% 2 10% 37% 36% 6%	630
	11th to 20th	Night	5% 3 9% 29% 41% 13%	630
	21st to end	Night	6% 2 6% 27% 49% 10%	630
July	1st to 10th	Night	8% 2 3 25% 46% 16%	615
	11th to 20th	Night	7% 2 2 19% 50% 20%	612
	21st to end	Night	7% 1 4 24% 50% 14%	690
August	1st to 10th	Night	8% 2 5% 25% 42% 17%	627
	11th to 20th	Night	9% 1 6% 22% 50% 12%	606
	21st to end	Night	14% 2 9% 26% 36% 13%	660
September	1st to 10th	Night	11% 3 8% 27% 41% 11%	745
	11th to 20th	Night	13% 2 12% 33% 35% 5%	800
	21st to end	Night	11% 2 14% 33% 38% 3	800
October	1st to 10th	Night	9% 3 21% 37% 25% 4	800
	11th to 20th	Night	12% 4 21% 36% 25% 3	800
	21st to end	Night	13% 4 23% 35% 22% 2	880
November	1st to 10th	Night	14% 5% 21% 38% 21% 2	820
	11th to 20th	Night	14% 8% 28% 36% 14% 1	840
	21st to end	Night	16% 7% 28% 34% 13% 1	840
December	1st to 10th	Night	21% 8% 28% 33% 10% 1	840
	11th to 20th	Night	20% 7% 30% 31% 10% 1	840
	21st to end	Night	27% 9% 24% 32% 8%	924

Page generated at 2026-08-12 02:37:19. Version ac07

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