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 2024-11-12.

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% 52%	105439
	Night	7% 9% 3 6% 4 4 4 4 5% 6% 48%	102421
Transparency	Day	31% 6% 10% 22% 20% 11%	105182
	Night	34% 7% 13% 23% 16% 7%	102267
Seeing	Day	11% 11% 23% 26% 20% 8%	14683
	Night	11% 7% 22% 37% 20% 3	23731

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	10% 14% 4 9% 7% 5% 6% 5% 7% 8% 24%	2539
	11th to 20th	Day	16% 16% 4 9% 5% 5% 6% 5% 5% 5% 23%	2540
	21st to end	Day	12% 14% 4 8% 6% 5% 5% 4 5% 8% 30%	2990
February	1st to 10th	Day	8% 12% 3 7% 6% 5% 6% 4 6% 9% 34%	1710
	11th to 20th	Day	7% 12% 3 9% 5% 5% 5% 5% 6% 8% 35%	1682
	21st to end	Day	6% 15% 4 9% 6% 6% 6% 6% 7% 7% 29%	1570
March	1st to 10th	Day	5% 10% 4 10% 7% 5% 5% 5% 7% 9% 33%	3157
	11th to 20th	Day	5% 10% 2 6% 4 4 4 3 4 7% 51%	3490
	21st to end	Day	7% 12% 4 11% 7% 6% 6% 5% 6% 7% 28%	4005
April	1st to 10th	Day	9% 14% 4 9% 6% 5% 5% 4 6% 6% 33%	2280
	11th to 20th	Day	10% 11% 3 9% 6% 4 4 4 6% 6% 38%	2249
	21st to end	Day	8% 9% 3 7% 5% 3 4 3 6% 8% 44%	2327
May	1st to 10th	Day	11% 9% 3 6% 4 4 4 4 5% 7% 45%	4420
	11th to 20th	Day	6% 5% 2 4 3 2 3 2 4 6% 63%	4377
	21st to end	Day	9% 6% 2 5% 4 4 5% 4 5% 7% 48%	4813
June	1st to 10th	Day	12% 8% 2 6% 5% 4 5% 3 6% 6% 43%	2660
	11th to 20th	Day	8% 5% 3 5% 2 4 4 3 5% 7% 54%	2660
	21st to end	Day	4 3 1 3 3 3 3 3 4 5% 67%	2660
July	1st to 10th	Day	1 1 1 1 2 2 2 2 3 85%	4420
	11th to 20th	Day	2 1 2 2 2 2 2 3 4 80%	4420
	21st to end	Day	1 1 1 2 1 2 2 2 3 4 82%	4790
August	1st to 10th	Day	4 3 1 3 3 3 3 3 4 5% 69%	4216
	11th to 20th	Day	2 2 1 3 2 2 2 3 4 6% 72%	3977
	21st to end	Day	3 4 1 3 2 2 2 2 3 4 74%	4180
September	1st to 10th	Day	2 2 1 2 2 3 2 2 4 6% 76%	2280
	11th to 20th	Day	5% 3 1 5% 3 3 4 4 5% 6% 61%	2280
	21st to end	Day	7% 6% 1 4 3 3 3 2 4 5% 60%	2039
October	1st to 10th	Day	6% 5% 1 4 3 2 3 2 3 5% 66%	3180
	11th to 20th	Day	5% 5% 2 5% 4 4 5% 4 6% 10% 50%	3161
	21st to end	Day	9% 9% 3 7% 5% 5% 5% 4 5% 6% 43%	3276
November	1st to 10th	Day	9% 11% 3 8% 5% 4 5% 4 6% 6% 38%	1764
	11th to 20th	Day	9% 9% 3 8% 6% 5% 7% 4 7% 8% 33%	1565
	21st to end	Day	7% 10% 4 7% 5% 5% 5% 4 7% 8% 38%	1520
December	1st to 10th	Day	7% 11% 4 7% 5% 4 3 5% 7% 8% 40%	1520
	11th to 20th	Day	9% 13% 4 9% 5% 6% 6% 5% 8% 7% 29%	1928
	21st to end	Day	8% 15% 4 10% 5% 5% 5% 4 7% 7% 30%	2794
January	1st to 10th	Night	8% 14% 5% 12% 7% 6% 6% 4 7% 7% 24%	4406
	11th to 20th	Night	13% 16% 5% 10% 6% 6% 5% 5% 6% 6% 22%	4420
	21st to end	Night	13% 15% 4 9% 5% 5% 5% 4 7% 7% 26%	4667
February	1st to 10th	Night	8% 13% 4 10% 6% 4 6% 4 7% 8% 32%	2470
	11th to 20th	Night	7% 12% 4 8% 5% 4 4 4 7% 8% 37%	2383
	21st to end	Night	6% 14% 4 10% 5% 6% 5% 5% 5% 8% 32%	1884
March	1st to 10th	Night	5% 11% 4 8% 5% 6% 6% 4 7% 9% 34%	3715
	11th to 20th	Night	5% 8% 2 6% 4 3 4 3 5% 6% 54%	3490
	21st to end	Night	7% 13% 4 10% 7% 6% 7% 6% 7% 8% 26%	3647
April	1st to 10th	Night	11% 13% 3 8% 6% 4 5% 4 5% 7% 36%	1900
	11th to 20th	Night	10% 13% 3 7% 5% 4 4 3 7% 6% 39%	1879
	21st to end	Night	9% 9% 3 6% 4 5% 5% 5% 7% 7% 41%	1851
May	1st to 10th	Night	10% 12% 2 6% 4 3 4 4 6% 5% 44%	2540
	11th to 20th	Night	5% 5% 2 4 3 3 3 3 4 5% 62%	2516
	21st to end	Night	11% 7% 2 4 3 3 4 3 5% 6% 52%	2762
June	1st to 10th	Night	12% 7% 2 5% 3 4 4 4 5% 6% 47%	1520
	11th to 20th	Night	8% 6% 2 4 2 3 3 2 5% 7% 57%	1520
	21st to end	Night	4 3 2 3 2 3 3 3 4 5% 70%	1520
July	1st to 10th	Night	1 1 1 1 1 2 1 2 3 86%	2540
	11th to 20th	Night	2 1 1 2 2 1 2 2 2 3 81%	2540
	21st to end	Night	1 1 2 1 1 2 2 3 3 83%	2761
August	1st to 10th	Night	2 2 1 4 2 3 3 2 5% 5% 70%	2715
	11th to 20th	Night	2 1 1 2 2 2 3 2 4 5% 76%	2862
	21st to end	Night	2 2 1 3 2 1 2 2 3 4 78%	3498
September	1st to 10th	Night	2 2 1 2 2 2 2 2 4 5% 78%	1900
	11th to 20th	Night	3 4 1 5% 2 4 4 3 4 6% 63%	1900
	21st to end	Night	7% 5% 2 3 2 2 3 3 3 7% 62%	2137
October	1st to 10th	Night	5% 5% 1 4 2 3 2 2 3 4 70%	3800
	11th to 20th	Night	7% 5% 2 5% 4 4 4 3 6% 9% 52%	3777
	21st to end	Night	8% 7% 2 7% 5% 5% 5% 5% 6% 7% 44%	4273
November	1st to 10th	Night	12% 11% 3 7% 5% 5% 5% 4 6% 7% 37%	2535
	11th to 20th	Night	11% 10% 3 8% 5% 5% 6% 4 7% 7% 34%	2635
	21st to end	Night	8% 11% 3 6% 4 4 4 4 6% 8% 41%	2660
December	1st to 10th	Night	7% 11% 4 8% 5% 4 4 4 5% 8% 39%	2660
	11th to 20th	Night	8% 12% 4 10% 6% 6% 6% 5% 7% 8% 29%	3276
	21st to end	Night	8% 13% 4 8% 6% 6% 5% 4 6% 7% 33%	4862

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	49% 11% 14% 20% 6%	2539
	11th to 20th	Day	57% 9% 11% 14% 5% 3	2540
	21st to end	Day	48% 10% 17% 18% 6% 2	2990
February	1st to 10th	Day	47% 7% 15% 21% 9% 1	1710
	11th to 20th	Day	43% 9% 16% 20% 10% 3	1691
	21st to end	Day	49% 10% 14% 16% 10% 1	1570
March	1st to 10th	Day	41% 6% 11% 23% 18% 1	3157
	11th to 20th	Day	31% 6% 13% 33% 17%	3490
	21st to end	Day	47% 10% 15% 21% 6%	4005
April	1st to 10th	Day	49% 7% 13% 18% 11% 2	2280
	11th to 20th	Day	46% 6% 13% 19% 13% 4	2252
	21st to end	Day	38% 7% 13% 26% 14% 2	2327
May	1st to 10th	Day	36% 6% 9% 28% 20% 1	4420
	11th to 20th	Day	24% 5% 6% 26% 34% 5%	4380
	21st to end	Day	33% 9% 15% 30% 13% 1	4814
June	1st to 10th	Day	41% 6% 10% 28% 13% 1	2660
	11th to 20th	Day	30% 6% 9% 32% 20% 4	2660
	21st to end	Day	20% 4 9% 29% 27% 11%	2660
July	1st to 10th	Day	9% 2 4 12% 20% 53%	4351
	11th to 20th	Day	11% 2 3 7% 23% 54%	4345
	21st to end	Day	9% 2 3 15% 39% 32%	4639
August	1st to 10th	Day	18% 3 4 14% 35% 26%	4200
	11th to 20th	Day	15% 3 5% 27% 34% 17%	4016
	21st to end	Day	17% 2 6% 26% 28% 21%	4179
September	1st to 10th	Day	13% 3 5% 24% 34% 23%	2280
	11th to 20th	Day	25% 5% 8% 24% 24% 13%	2280
	21st to end	Day	26% 4 10% 25% 23% 12%	2039
October	1st to 10th	Day	24% 3 10% 19% 26% 18%	3180
	11th to 20th	Day	30% 5% 16% 25% 21% 3	3161
	21st to end	Day	41% 5% 8% 24% 20% 2	3276
November	1st to 10th	Day	44% 6% 13% 23% 14% 1	1764
	11th to 20th	Day	45% 10% 19% 16% 10% 1	1565
	21st to end	Day	42% 9% 15% 17% 16% 1	1520
December	1st to 10th	Day	39% 10% 16% 23% 12% 1	1520
	11th to 20th	Day	49% 8% 16% 16% 10%	1928
	21st to end	Day	49% 8% 13% 24% 5% 1	2794
January	1st to 10th	Night	52% 11% 16% 16% 5%	4406
	11th to 20th	Night	53% 10% 13% 15% 6% 3	4420
	21st to end	Night	54% 9% 13% 16% 7% 1	4667
February	1st to 10th	Night	47% 9% 17% 16% 9% 1	2470
	11th to 20th	Night	43% 9% 16% 21% 9% 2	2385
	21st to end	Night	46% 11% 14% 19% 9% 1	1884
March	1st to 10th	Night	38% 9% 11% 26% 15% 1	3715
	11th to 20th	Night	28% 7% 14% 33% 17%	3490
	21st to end	Night	46% 11% 18% 18% 6%	3647
April	1st to 10th	Night	45% 8% 18% 18% 9% 1	1900
	11th to 20th	Night	44% 7% 15% 20% 12% 2	1879
	21st to end	Night	40% 9% 15% 24% 11% 1	1851
May	1st to 10th	Night	36% 8% 12% 29% 14%	2540
	11th to 20th	Night	23% 8% 10% 36% 22% 2	2516
	21st to end	Night	29% 10% 28% 27% 6%	2762
June	1st to 10th	Night	38% 8% 12% 30% 12% 1	1520
	11th to 20th	Night	26% 7% 12% 36% 15% 3	1520
	21st to end	Night	18% 5% 11% 33% 26% 7%	1520
July	1st to 10th	Night	7% 2 6% 15% 25% 45%	2500
	11th to 20th	Night	11% 3 3 14% 22% 47%	2492
	21st to end	Night	10% 2 3 18% 39% 28%	2674
August	1st to 10th	Night	16% 3 5% 18% 40% 18%	2707
	11th to 20th	Night	12% 2 7% 39% 30% 10%	2889
	21st to end	Night	14% 2 8% 30% 30% 16%	3498
September	1st to 10th	Night	10% 3 6% 28% 35% 18%	1900
	11th to 20th	Night	22% 5% 10% 24% 26% 12%	1900
	21st to end	Night	24% 5% 8% 25% 25% 13%	2137
October	1st to 10th	Night	21% 3 8% 23% 33% 13%	3800
	11th to 20th	Night	29% 4 21% 23% 18% 3	3777
	21st to end	Night	38% 6% 11% 28% 15% 2	4273
November	1st to 10th	Night	45% 7% 13% 18% 14% 3	2535
	11th to 20th	Night	45% 10% 15% 20% 9% 1	2635
	21st to end	Night	38% 8% 16% 18% 17% 3	2660
December	1st to 10th	Night	41% 9% 16% 22% 11% 2	2660
	11th to 20th	Night	48% 11% 13% 18% 10%	3276
	21st to end	Night	47% 9% 13% 22% 8% 1	4862

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	19% 18% 31% 18% 13% 1	180
	11th to 20th	Day	18% 13% 29% 23% 14% 3	180
	21st to end	Day	14% 11% 27% 28% 18% 1	316
February	1st to 10th	Day	18% 13% 24% 32% 11% 1	370
	11th to 20th	Day	18% 16% 31% 22% 11% 2	374
	21st to end	Day	16% 16% 27% 28% 11% 2	382
March	1st to 10th	Day	14% 16% 30% 29% 10% 1	460
	11th to 20th	Day	17% 15% 24% 26% 15% 4	460
	21st to end	Day	18% 18% 24% 24% 13% 2	506
April	1st to 10th	Day	20% 16% 22% 24% 13% 5%	460
	11th to 20th	Day	16% 17% 26% 24% 11% 6%	452
	21st to end	Day	13% 16% 25% 23% 17% 6%	460
May	1st to 10th	Day	12% 14% 25% 25% 16% 8%	463
	11th to 20th	Day	19% 10% 22% 21% 19% 9%	488
	21st to end	Day	15% 8% 18% 26% 21% 12%	529
June	1st to 10th	Day	12% 10% 22% 22% 21% 13%	490
	11th to 20th	Day	10% 14% 28% 22% 20% 6%	490
	21st to end	Day	4 8% 21% 27% 27% 13%	490
July	1st to 10th	Day	3 4 25% 32% 24% 12%	486
	11th to 20th	Day	3 5% 25% 25% 27% 14%	484
	21st to end	Day	2 4 25% 27% 25% 16%	531
August	1st to 10th	Day	2 3 22% 28% 26% 17%	487
	11th to 20th	Day	2 4 19% 29% 26% 21%	477
	21st to end	Day	5% 8% 18% 26% 28% 15%	539
September	1st to 10th	Day	4 4 19% 27% 31% 15%	490
	11th to 20th	Day	7% 7% 17% 30% 30% 10%	490
	21st to end	Day	10% 7% 20% 28% 27% 8%	490
October	1st to 10th	Day	13% 8% 19% 27% 24% 10%	490
	11th to 20th	Day	13% 11% 19% 24% 28% 6%	490
	21st to end	Day	14% 13% 23% 24% 19% 7%	442
November	1st to 10th	Day	15% 11% 24% 30% 15% 5%	300
	11th to 20th	Day	13% 15% 23% 28% 17% 5%	199
	21st to end	Day	16% 11% 22% 31% 16% 3	180
December	1st to 10th	Day	12% 10% 26% 32% 15% 6%	180
	11th to 20th	Day	13% 18% 31% 32% 7%	180
	21st to end	Day	16% 16% 25% 31% 10% 2	198
January	1st to 10th	Night	14% 11% 32% 28% 13% 2	760
	11th to 20th	Night	12% 13% 26% 29% 17% 3	760
	21st to end	Night	15% 7% 25% 35% 15% 2	836
February	1st to 10th	Night	14% 12% 27% 33% 12% 1	760
	11th to 20th	Night	12% 9% 28% 35% 14% 2	744
	21st to end	Night	13% 11% 28% 36% 11% 1	628
March	1st to 10th	Night	12% 13% 28% 34% 12% 2	760
	11th to 20th	Night	10% 10% 24% 39% 15% 2	760
	21st to end	Night	12% 11% 29% 32% 14% 2	836
April	1st to 10th	Night	16% 10% 22% 32% 18% 1	760
	11th to 20th	Night	15% 9% 27% 29% 17% 3	751
	21st to end	Night	13% 8% 24% 35% 17% 2	711
May	1st to 10th	Night	12% 4 17% 43% 21% 1	380
	11th to 20th	Night	10% 5% 16% 42% 25% 2	374
	21st to end	Night	17% 4 13% 37% 26% 3	411
June	1st to 10th	Night	14% 4 18% 41% 21% 2	380
	11th to 20th	Night	9% 3 22% 45% 20% 1	380
	21st to end	Night	5% 1 17% 50% 26% 1	380
July	1st to 10th	Night	2 1 12% 53% 32% 1	370
	11th to 20th	Night	2 1 14% 56% 24% 1	368
	21st to end	Night	1 1 10% 55% 31% 2	416
August	1st to 10th	Night	3 9% 45% 38% 5%	486
	11th to 20th	Night	2 1 7% 40% 43% 8%	588
	21st to end	Night	2 3 16% 44% 32% 3	836
September	1st to 10th	Night	3 2 14% 44% 33% 4	760
	11th to 20th	Night	6% 2 12% 39% 33% 7%	760
	21st to end	Night	9% 4 13% 38% 31% 5%	760
October	1st to 10th	Night	10% 3 16% 40% 27% 4	760
	11th to 20th	Night	11% 4 20% 36% 23% 5%	760
	21st to end	Night	13% 7% 23% 35% 16% 6%	836
November	1st to 10th	Night	16% 8% 26% 36% 14% 2	780
	11th to 20th	Night	14% 11% 27% 32% 14% 2	764
	21st to end	Night	12% 9% 24% 35% 17% 3	760
December	1st to 10th	Night	13% 9% 24% 31% 21% 2	760
	11th to 20th	Night	13% 13% 29% 31% 14% 1	760
	21st to end	Night	15% 14% 34% 26% 11% 1	836

Page generated at 2024-11-08 19:45:37. Version ac07

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