Pooler Skies Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pooler Skies Observatory clear sky chart from 2005-11-06 to 2026-01-02.

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	6% 7% 2 6% 4 4 4 3 5% 6% 53%	136416
	Night	7% 8% 2 6% 4 4 4 3 5% 6% 49%	132256
Transparency	Day	31% 5% 10% 23% 20% 11%	131223
	Night	34% 6% 12% 24% 17% 6%	128456
Seeing	Day	12% 11% 23% 26% 20% 9%	16056
	Night	11% 7% 22% 37% 20% 3	25185

By Month

Percentage Cloud Cover SW (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% 15% 4 10% 7% 5% 6% 4 6% 8% 22%	3647
	11th to 20th	Day	11% 11% 3 7% 4 4 5% 4 4 5% 41%	3640
	21st to end	Day	9% 11% 3 6% 4 4 4 4 5% 7% 44%	4298
February	1st to 10th	Day	8% 12% 3 8% 6% 5% 6% 4 6% 9% 33%	1800
	11th to 20th	Day	7% 12% 3 9% 6% 5% 5% 5% 6% 8% 35%	1773
	21st to end	Day	6% 15% 4 9% 6% 6% 6% 5% 6% 7% 30%	1650
March	1st to 10th	Day	7% 9% 3 9% 6% 5% 4 4 6% 10% 36%	4550
	11th to 20th	Day	6% 14% 3 8% 5% 5% 5% 3 5% 6% 39%	5000
	21st to end	Day	7% 12% 4 10% 7% 6% 6% 5% 7% 7% 29%	5744
April	1st to 10th	Day	8% 14% 4 9% 6% 5% 5% 4 6% 6% 33%	2400
	11th to 20th	Day	9% 11% 3 8% 6% 4 4 4 6% 6% 40%	2369
	21st to end	Day	8% 9% 3 7% 4 4 4 3 6% 8% 45%	2449
May	1st to 10th	Day	10% 7% 2 5% 3 3 4 3 5% 6% 52%	6320
	11th to 20th	Day	7% 6% 2 6% 4 3 4 3 5% 7% 53%	6277
	21st to end	Day	7% 5% 2 5% 3 3 4 4 5% 8% 54%	6902
June	1st to 10th	Day	11% 8% 2 6% 4 4 4 3 6% 6% 46%	2800
	11th to 20th	Day	8% 5% 2 5% 3 4 4 3 5% 7% 55%	2800
	21st to end	Day	4 3 1 3 3 3 3 3 4 5% 67%	2800
July	1st to 10th	Day	2 2 1 2 1 2 2 2 3 3 81%	6319
	11th to 20th	Day	1 1 2 1 1 2 2 2 3 84%	6320
	21st to end	Day	2 1 1 2 2 2 2 2 3 5% 79%	6880
August	1st to 10th	Day	3 2 1 3 3 3 3 3 5% 6% 68%	5952
	11th to 20th	Day	3 2 1 2 2 2 2 3 3 5% 75%	5721
	21st to end	Day	5% 4 1 3 2 3 3 3 4 5% 66%	5984
September	1st to 10th	Day	2 2 1 3 2 3 2 2 4 6% 74%	2400
	11th to 20th	Day	5% 3 1 5% 3 3 4 4 5% 6% 61%	2400
	21st to end	Day	7% 6% 1 4 3 3 3 2 4 5% 61%	2146
October	1st to 10th	Day	6% 5% 1 5% 3 2 3 2 3 5% 65%	3280
	11th to 20th	Day	5% 5% 2 5% 4 4 5% 4 6% 10% 50%	3261
	21st to end	Day	9% 9% 3 7% 5% 5% 5% 4 5% 6% 43%	3381
November	1st to 10th	Day	9% 11% 3 8% 5% 5% 5% 4 6% 7% 38%	1854
	11th to 20th	Day	9% 9% 3 9% 7% 6% 6% 4 7% 8% 32%	1719
	21st to end	Day	7% 10% 4 8% 5% 5% 5% 4 7% 8% 38%	1680
December	1st to 10th	Day	6% 8% 3 5% 3 3 3 4 5% 7% 54%	2700
	11th to 20th	Day	10% 14% 4 9% 6% 6% 6% 4 7% 7% 26%	3108
	21st to end	Day	10% 14% 4 10% 6% 6% 6% 4 7% 8% 26%	4092
January	1st to 10th	Night	11% 15% 5% 13% 7% 6% 6% 4 7% 7% 21%	6320
	11th to 20th	Night	9% 11% 4 8% 4 4 4 4 4 5% 42%	6320
	21st to end	Night	10% 11% 3 7% 4 4 4 3 5% 7% 41%	6666
February	1st to 10th	Night	8% 13% 4 10% 6% 4 5% 4 7% 7% 31%	2600
	11th to 20th	Night	7% 12% 4 8% 5% 4 5% 4 7% 7% 36%	2512
	21st to end	Night	6% 14% 4 10% 5% 5% 5% 6% 5% 8% 33%	1980
March	1st to 10th	Night	6% 10% 3 7% 5% 5% 6% 5% 8% 9% 35%	5342
	11th to 20th	Night	6% 8% 3 7% 5% 5% 5% 4 6% 7% 46%	5000
	21st to end	Night	8% 11% 3 9% 6% 6% 7% 5% 7% 8% 30%	5230
April	1st to 10th	Night	11% 12% 3 8% 5% 4 5% 3 5% 7% 36%	2000
	11th to 20th	Night	9% 12% 3 7% 5% 4 4 3 7% 6% 40%	1979
	21st to end	Night	9% 9% 3 6% 4 5% 5% 5% 7% 7% 42%	1948
May	1st to 10th	Night	8% 10% 2 5% 3 3 3 3 5% 5% 53%	3640
	11th to 20th	Night	6% 6% 2 6% 4 4 4 4 4 6% 55%	3616
	21st to end	Night	9% 6% 2 4 3 3 4 3 5% 6% 57%	3972
June	1st to 10th	Night	11% 7% 2 5% 3 4 4 4 5% 6% 49%	1600
	11th to 20th	Night	8% 6% 2 4 2 3 4 3 5% 7% 57%	1600
	21st to end	Night	4 3 2 3 2 3 3 3 4 5% 69%	1600
July	1st to 10th	Night	2 1 1 2 2 2 3 2 2 4 79%	3640
	11th to 20th	Night	2 1 1 1 1 2 1 2 2 86%	3640
	21st to end	Night	3 2 1 3 2 2 3 2 3 4 77%	3970
August	1st to 10th	Night	4 2 1 4 3 3 4 3 5% 6% 65%	3848
	11th to 20th	Night	2 1 1 2 2 2 3 3 4 5% 77%	4116
	21st to end	Night	4 3 1 3 2 2 3 2 4 5% 71%	5015
September	1st to 10th	Night	2 2 1 2 2 2 3 2 4 5% 76%	2000
	11th to 20th	Night	4 4 1 5% 2 4 4 3 4 7% 63%	2000
	21st to end	Night	6% 5% 2 3 2 2 3 3 4 7% 62%	2250
October	1st to 10th	Night	5% 5% 1 4 2 3 3 2 3 4 69%	3920
	11th to 20th	Night	8% 5% 2 5% 4 4 4 3 5% 8% 52%	3897
	21st to end	Night	8% 7% 3 7% 5% 5% 5% 5% 6% 7% 44%	4410
November	1st to 10th	Night	12% 11% 3 6% 5% 5% 5% 4 6% 7% 36%	2665
	11th to 20th	Night	11% 10% 3 9% 5% 5% 6% 4 7% 7% 33%	2898
	21st to end	Night	8% 11% 3 6% 4 4 4 4 6% 8% 42%	2940
December	1st to 10th	Night	5% 7% 2 5% 3 3 3 3 4 7% 56%	4700
	11th to 20th	Night	11% 13% 4 10% 6% 6% 6% 5% 6% 7% 25%	5316
	21st to end	Night	12% 13% 4 8% 5% 5% 5% 4 6% 7% 31%	7106

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	55% 8% 12% 20% 6%	3647
	11th to 20th	Day	42% 7% 10% 25% 14% 2	3640
	21st to end	Day	36% 7% 12% 19% 19% 7%	4298
February	1st to 10th	Day	48% 7% 15% 20% 10% 1	1800
	11th to 20th	Day	44% 8% 15% 19% 11% 3	1782
	21st to end	Day	48% 10% 14% 16% 11% 2	1650
March	1st to 10th	Day	40% 5% 9% 27% 17% 3	4550
	11th to 20th	Day	43% 6% 10% 27% 15%	5000
	21st to end	Day	47% 9% 15% 21% 8% 1	5744
April	1st to 10th	Day	49% 7% 13% 19% 11% 2	2400
	11th to 20th	Day	44% 6% 12% 19% 15% 4	2372
	21st to end	Day	37% 7% 13% 26% 15% 2	2449
May	1st to 10th	Day	31% 4 6% 28% 26% 4	6320
	11th to 20th	Day	30% 5% 10% 27% 25% 4	6280
	21st to end	Day	27% 7% 14% 35% 16% 1	6904
June	1st to 10th	Day	39% 6% 10% 30% 14% 2	2800
	11th to 20th	Day	29% 6% 9% 31% 21% 4	2800
	21st to end	Day	20% 4 9% 29% 27% 11%	2800
July	1st to 10th	Day	11% 2 4 16% 28% 40%	6251
	11th to 20th	Day	9% 2 4 8% 22% 56%	6245
	21st to end	Day	11% 1 3 25% 38% 22%	6681
August	1st to 10th	Day	18% 3 4 15% 34% 25%	4334
	11th to 20th	Day	15% 3 5% 27% 34% 17%	4144
	21st to end	Day	17% 2 5% 26% 28% 21%	4311
September	1st to 10th	Day	14% 3 5% 24% 33% 21%	2400
	11th to 20th	Day	24% 5% 8% 25% 25% 13%	2400
	21st to end	Day	25% 4 10% 25% 23% 12%	2146
October	1st to 10th	Day	24% 3 10% 19% 26% 18%	3280
	11th to 20th	Day	30% 5% 16% 25% 21% 4	3261
	21st to end	Day	41% 5% 8% 24% 20% 2	3381
November	1st to 10th	Day	44% 6% 14% 23% 13% 1	1854
	11th to 20th	Day	46% 9% 18% 16% 10%	1719
	21st to end	Day	42% 8% 15% 18% 15% 1	1680
December	1st to 10th	Day	30% 6% 12% 27% 24% 2	2700
	11th to 20th	Day	55% 5% 17% 15% 8%	3108
	21st to end	Day	52% 7% 13% 22% 6% 1	4092
January	1st to 10th	Night	57% 8% 14% 16% 5%	6320
	11th to 20th	Night	39% 8% 10% 27% 14% 2	6320
	21st to end	Night	42% 6% 9% 17% 18% 7%	6666
February	1st to 10th	Night	48% 9% 17% 16% 10% 1	2600
	11th to 20th	Night	44% 9% 16% 20% 10% 2	2514
	21st to end	Night	46% 11% 13% 19% 9% 1	1980
March	1st to 10th	Night	38% 7% 10% 27% 15% 2	5342
	11th to 20th	Night	33% 7% 14% 29% 17%	5000
	21st to end	Night	45% 11% 16% 21% 7%	5230
April	1st to 10th	Night	44% 8% 18% 19% 9% 1	2000
	11th to 20th	Night	43% 7% 14% 21% 13% 2	1979
	21st to end	Night	39% 9% 15% 25% 11% 1	1948
May	1st to 10th	Night	30% 6% 9% 28% 26% 1	3637
	11th to 20th	Night	30% 6% 16% 30% 17% 1	3616
	21st to end	Night	26% 7% 26% 32% 8%	3972
June	1st to 10th	Night	36% 7% 12% 31% 13% 1	1600
	11th to 20th	Night	26% 7% 12% 36% 16% 3	1600
	21st to end	Night	18% 5% 12% 33% 25% 7%	1600
July	1st to 10th	Night	13% 2 6% 21% 27% 32%	3600
	11th to 20th	Night	8% 2 4 14% 25% 48%	3592
	21st to end	Night	15% 2 3 30% 31% 20%	3857
August	1st to 10th	Night	16% 3 5% 19% 38% 18%	2793
	11th to 20th	Night	12% 2 7% 39% 30% 10%	2980
	21st to end	Night	14% 2 8% 30% 30% 16%	3608
September	1st to 10th	Night	13% 3 6% 27% 34% 17%	2000
	11th to 20th	Night	22% 5% 10% 25% 26% 11%	2000
	21st to end	Night	24% 5% 8% 25% 25% 13%	2250
October	1st to 10th	Night	22% 3 8% 23% 32% 12%	3920
	11th to 20th	Night	30% 4 21% 24% 18% 3	3897
	21st to end	Night	37% 6% 11% 28% 16% 2	4410
November	1st to 10th	Night	45% 7% 14% 18% 13% 3	2665
	11th to 20th	Night	46% 9% 15% 20% 9% 1	2898
	21st to end	Night	38% 8% 16% 20% 17% 2	2940
December	1st to 10th	Night	28% 6% 11% 30% 24% 1	4700
	11th to 20th	Night	54% 8% 13% 17% 7%	5316
	21st to end	Night	49% 8% 15% 19% 8% 1	7106

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% 16% 31% 18% 13% 1	202
	11th to 20th	Day	16% 12% 29% 26% 13% 5%	200
	21st to end	Day	14% 10% 27% 29% 17% 3	345
February	1st to 10th	Day	19% 13% 24% 32% 11% 1	400
	11th to 20th	Day	17% 15% 32% 23% 11% 2	405
	21st to end	Day	16% 16% 27% 28% 11% 2	414
March	1st to 10th	Day	15% 15% 30% 30% 10% 1	500
	11th to 20th	Day	19% 15% 24% 25% 14% 4	500
	21st to end	Day	18% 18% 25% 24% 13% 2	550
April	1st to 10th	Day	19% 15% 22% 25% 13% 5%	500
	11th to 20th	Day	15% 17% 26% 25% 11% 6%	492
	21st to end	Day	13% 15% 25% 23% 19% 6%	500
May	1st to 10th	Day	12% 14% 25% 24% 18% 8%	503
	11th to 20th	Day	19% 11% 23% 20% 18% 8%	528
	21st to end	Day	14% 7% 19% 26% 21% 12%	573
June	1st to 10th	Day	12% 10% 22% 22% 22% 13%	530
	11th to 20th	Day	9% 14% 28% 23% 20% 6%	530
	21st to end	Day	4 8% 21% 26% 28% 13%	530
July	1st to 10th	Day	3 4 25% 31% 25% 12%	526
	11th to 20th	Day	3 5% 24% 26% 27% 15%	524
	21st to end	Day	3 4 25% 28% 24% 17%	575
August	1st to 10th	Day	2 4 22% 28% 26% 19%	527
	11th to 20th	Day	2 4 19% 28% 26% 21%	517
	21st to end	Day	5% 7% 18% 26% 28% 15%	583
September	1st to 10th	Day	4 4 18% 26% 32% 16%	530
	11th to 20th	Day	7% 6% 16% 29% 30% 12%	530
	21st to end	Day	10% 7% 19% 27% 27% 9%	530
October	1st to 10th	Day	14% 8% 19% 27% 24% 9%	530
	11th to 20th	Day	13% 11% 19% 25% 27% 5%	530
	21st to end	Day	15% 13% 23% 24% 20% 6%	481
November	1st to 10th	Day	15% 12% 25% 28% 15% 5%	330
	11th to 20th	Day	15% 14% 23% 28% 16% 5%	239
	21st to end	Day	14% 10% 22% 33% 17% 4	220
December	1st to 10th	Day	12% 10% 25% 30% 17% 6%	220
	11th to 20th	Day	14% 18% 30% 29% 8%	220
	21st to end	Day	18% 17% 25% 29% 9% 2	242
January	1st to 10th	Night	14% 11% 32% 28% 13% 2	804
	11th to 20th	Night	11% 13% 26% 30% 17% 3	800
	21st to end	Night	15% 7% 26% 35% 15% 2	880
February	1st to 10th	Night	15% 12% 27% 33% 12% 1	800
	11th to 20th	Night	12% 9% 29% 35% 14% 2	784
	21st to end	Night	14% 11% 28% 36% 10% 1	660
March	1st to 10th	Night	12% 12% 28% 35% 12% 2	800
	11th to 20th	Night	11% 10% 25% 38% 15% 2	800
	21st to end	Night	12% 12% 29% 32% 14% 2	880
April	1st to 10th	Night	16% 10% 22% 33% 18% 1	800
	11th to 20th	Night	15% 9% 27% 30% 16% 3	791
	21st to end	Night	12% 8% 24% 36% 18% 1	748
May	1st to 10th	Night	12% 5% 17% 44% 21% 1	400
	11th to 20th	Night	10% 5% 16% 43% 24% 2	394
	21st to end	Night	16% 4 13% 39% 25% 3	433
June	1st to 10th	Night	14% 4 18% 42% 22% 2	400
	11th to 20th	Night	9% 3 22% 46% 19% 1	400
	21st to end	Night	6% 1 17% 50% 26% 1	400
July	1st to 10th	Night	2 1 13% 53% 31% 1	390
	11th to 20th	Night	2 1 14% 57% 25% 1	388
	21st to end	Night	2 1 10% 55% 31% 2	438
August	1st to 10th	Night	3 9% 46% 38% 5%	512
	11th to 20th	Night	2 1 7% 41% 42% 7%	619
	21st to end	Night	2 3 16% 44% 32% 3	880
September	1st to 10th	Night	3 2 14% 44% 33% 4	800
	11th to 20th	Night	6% 3 12% 40% 33% 7%	800
	21st to end	Night	9% 4 13% 38% 31% 5%	800
October	1st to 10th	Night	11% 3 17% 39% 27% 3	800
	11th to 20th	Night	11% 5% 21% 37% 22% 5%	800
	21st to end	Night	13% 7% 23% 35% 16% 6%	880
November	1st to 10th	Night	16% 8% 25% 35% 14% 1	820
	11th to 20th	Night	15% 11% 28% 31% 13% 2	840
	21st to end	Night	13% 9% 24% 35% 16% 2	840
December	1st to 10th	Night	12% 10% 24% 31% 21% 2	840
	11th to 20th	Night	13% 13% 30% 30% 13% 1	840
	21st to end	Night	16% 13% 34% 25% 11% 1	924

Page generated at 2025-12-29 22:14:06. Version ac07

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