Possum Poop Hollow Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Possum Poop Hollow Observatory clear sky chart from 2005-11-06 to 2026-04-17.

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	16% 10% 3 8% 5% 4 5% 4 6% 7% 32%	131141
	Night	17% 11% 4 8% 5% 4 4 3 5% 6% 32%	130967
Transparency	Day	50% 5% 10% 21% 12% 2	134759
	Night	52% 4 10% 20% 12% 2	135419
Seeing	Day	24% 13% 25% 21% 12% 4	16688
	Night	23% 10% 24% 28% 13% 1	26911

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	19% 19% 8% 15% 6% 3 3 2 3 5% 17%	5258
	11th to 20th	Day	15% 20% 7% 15% 8% 4 4 2 3 3 18%	5280
	21st to end	Day	18% 16% 5% 12% 7% 5% 5% 3 5% 5% 19%	5780
February	1st to 10th	Day	22% 14% 4 9% 6% 3 4 2 4 5% 26%	1890
	11th to 20th	Day	20% 16% 4 11% 5% 4 3 3 4 5% 23%	1892
	21st to end	Day	21% 15% 4 10% 4 3 3 2 4 5% 28%	1744
March	1st to 10th	Day	18% 16% 4 7% 4 3 3 3 4 5% 33%	5045
	11th to 20th	Day	14% 8% 3 6% 4 4 5% 3 5% 7% 41%	5090
	21st to end	Day	19% 10% 3 8% 6% 4 5% 4 6% 7% 29%	5586
April	1st to 10th	Day	18% 11% 3 7% 5% 5% 4 3 5% 6% 33%	2372
	11th to 20th	Day	16% 9% 2 6% 4 4 4 3 5% 7% 38%	2495
	21st to end	Day	20% 8% 3 7% 4 3 4 4 6% 8% 33%	2600
May	1st to 10th	Day	19% 9% 3 8% 6% 5% 6% 5% 7% 7% 25%	5862
	11th to 20th	Day	19% 8% 3 7% 5% 5% 5% 4 6% 7% 31%	5861
	21st to end	Day	18% 7% 2 6% 4 5% 5% 4 6% 9% 33%	6433
June	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 5% 6% 9% 37%	2660
	11th to 20th	Day	13% 6% 2 7% 5% 6% 6% 5% 7% 8% 37%	2785
	21st to end	Day	13% 6% 2 5% 5% 5% 6% 5% 7% 9% 38%	2600
July	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 4 6% 8% 42%	5900
	11th to 20th	Day	14% 6% 2 7% 5% 5% 6% 5% 7% 10% 32%	5900
	21st to end	Day	16% 7% 3 7% 5% 5% 5% 4 6% 9% 33%	6424
August	1st to 10th	Day	12% 7% 3 8% 5% 5% 6% 5% 7% 10% 32%	4234
	11th to 20th	Day	12% 6% 2 7% 4 4 6% 5% 7% 9% 38%	4174
	21st to end	Day	7% 4 2 5% 5% 5% 5% 4 7% 9% 48%	4477
September	1st to 10th	Day	15% 5% 2 4 3 3 4 4 5% 6% 48%	2330
	11th to 20th	Day	12% 6% 2 5% 4 5% 4 3 6% 7% 46%	2200
	21st to end	Day	20% 8% 3 6% 5% 4 3 4 5% 6% 37%	2200
October	1st to 10th	Day	16% 6% 2 5% 3 4 4 3 5% 8% 44%	2037
	11th to 20th	Day	18% 7% 2 7% 4 4 4 3 6% 6% 41%	2000
	21st to end	Day	22% 8% 2 6% 4 4 3 3 5% 5% 39%	2200
November	1st to 10th	Day	13% 8% 2 5% 4 4 4 4 4 6% 46%	1973
	11th to 20th	Day	16% 12% 3 7% 4 3 4 4 6% 6% 33%	1890
	21st to end	Day	19% 14% 5% 7% 3 3 3 3 5% 6% 31%	1719
December	1st to 10th	Day	21% 13% 5% 17% 5% 3 3 3 3 4 22%	2680
	11th to 20th	Day	24% 15% 5% 9% 4 3 3 3 4 5% 24%	3070
	21st to end	Day	21% 17% 4 10% 5% 4 5% 4 5% 6% 19%	4500
January	1st to 10th	Night	19% 17% 7% 17% 5% 4 4 3 4 4 19%	7635
	11th to 20th	Night	17% 16% 8% 15% 7% 5% 3 3 3 4 20%	7680
	21st to end	Night	20% 13% 5% 10% 7% 6% 3 3 4 4 27%	8401
February	1st to 10th	Night	21% 14% 4 9% 6% 3 4 3 4 5% 27%	2730
	11th to 20th	Night	22% 15% 4 9% 5% 5% 4 3 5% 4 24%	2610
	21st to end	Night	22% 15% 5% 7% 4 3 4 3 5% 5% 27%	2060
March	1st to 10th	Night	22% 12% 3 6% 4 3 3 3 4 5% 34%	5028
	11th to 20th	Night	13% 9% 4 6% 3 4 4 3 5% 7% 41%	5090
	21st to end	Night	17% 9% 3 8% 5% 5% 4 4 5% 5% 34%	5588
April	1st to 10th	Night	20% 12% 2 6% 5% 3 4 3 4 8% 34%	2247
	11th to 20th	Night	17% 8% 3 6% 4 4 4 4 5% 8% 38%	2003
	21st to end	Night	17% 6% 3 6% 4 4 4 3 6% 6% 40%	1800
May	1st to 10th	Night	26% 10% 3 8% 4 5% 5% 3 5% 7% 24%	4033
	11th to 20th	Night	17% 7% 2 7% 5% 4 5% 4 6% 8% 35%	4032
	21st to end	Night	21% 9% 3 7% 4 5% 4 3 5% 7% 32%	4421
June	1st to 10th	Night	13% 6% 2 4 4 5% 5% 4 6% 8% 43%	1725
	11th to 20th	Night	10% 5% 2 7% 5% 5% 4 5% 6% 10% 39%	1601
	21st to end	Night	13% 5% 2 5% 4 5% 4 4 7% 10% 42%	1799
July	1st to 10th	Night	11% 7% 2 7% 5% 5% 6% 4 7% 8% 38%	4058
	11th to 20th	Night	15% 7% 3 8% 5% 5% 5% 4 6% 9% 34%	4057
	21st to end	Night	12% 7% 2 7% 5% 5% 5% 5% 7% 8% 37%	4427
August	1st to 10th	Night	13% 7% 3 8% 5% 5% 6% 4 7% 9% 34%	2915
	11th to 20th	Night	14% 7% 2 6% 5% 5% 5% 3 5% 8% 40%	2875
	21st to end	Night	7% 5% 2 6% 4 5% 6% 4 6% 9% 47%	3388
September	1st to 10th	Night	12% 6% 3 6% 4 4 4 3 5% 6% 47%	2065
	11th to 20th	Night	10% 4 1 5% 3 4 4 4 6% 6% 52%	2200
	21st to end	Night	17% 7% 3 6% 5% 4 4 3 4 6% 41%	2200
October	1st to 10th	Night	14% 5% 2 6% 3 3 4 3 5% 7% 47%	2362
	11th to 20th	Night	15% 6% 2 6% 3 5% 4 3 5% 7% 44%	2400
	21st to end	Night	23% 7% 2 5% 3 4 3 3 4 5% 41%	2640
November	1st to 10th	Night	13% 8% 2 6% 3 3 4 3 5% 5% 47%	2540
	11th to 20th	Night	20% 12% 3 6% 5% 3 4 4 4 6% 33%	2730
	21st to end	Night	19% 13% 4 8% 5% 4 4 3 4 5% 31%	2896
December	1st to 10th	Night	19% 14% 5% 16% 4 4 4 3 4 5% 23%	4720
	11th to 20th	Night	21% 16% 7% 8% 5% 4 3 3 3 4 24%	5345
	21st to end	Night	19% 17% 5% 10% 5% 5% 4 3 5% 5% 22%	6666

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	73% 2 10% 12% 3	5259
	11th to 20th	Day	73% 3 5% 10% 8% 1	5280
	21st to end	Day	68% 3 8% 14% 6% 1	5780
February	1st to 10th	Day	63% 3 8% 18% 8%	1890
	11th to 20th	Day	63% 4 8% 16% 8% 1	1901
	21st to end	Day	60% 3 9% 17% 10% 1	1744
March	1st to 10th	Day	54% 2 6% 23% 11% 4	5045
	11th to 20th	Day	43% 3 7% 30% 13% 3	5090
	21st to end	Day	54% 4 7% 21% 13% 2	5586
April	1st to 10th	Day	52% 4 10% 18% 13% 3	2372
	11th to 20th	Day	46% 4 11% 19% 18% 3	2495
	21st to end	Day	49% 4 11% 22% 12% 2	2600
May	1st to 10th	Day	55% 5% 10% 19% 8% 2	5897
	11th to 20th	Day	52% 5% 10% 22% 10% 1	5865
	21st to end	Day	46% 6% 13% 21% 12% 2	6447
June	1st to 10th	Day	42% 6% 14% 22% 15% 2	2660
	11th to 20th	Day	45% 6% 13% 22% 13% 1	2785
	21st to end	Day	41% 6% 14% 24% 14% 1	2600
July	1st to 10th	Day	39% 7% 10% 24% 17% 2	5835
	11th to 20th	Day	45% 8% 12% 24% 10% 1	5831
	21st to end	Day	47% 6% 10% 19% 18% 1	6240
August	1st to 10th	Day	45% 7% 13% 26% 8%	4221
	11th to 20th	Day	40% 6% 10% 31% 13%	4213
	21st to end	Day	31% 6% 14% 31% 17% 2	4477
September	1st to 10th	Day	36% 5% 10% 22% 24% 4	2330
	11th to 20th	Day	37% 5% 9% 28% 18% 3	2200
	21st to end	Day	49% 3 9% 19% 18% 1	2200
October	1st to 10th	Day	31% 3 7% 26% 29% 3	3310
	11th to 20th	Day	38% 4 10% 25% 17% 7%	3240
	21st to end	Day	34% 3 9% 31% 20% 4	3538
November	1st to 10th	Day	40% 3 10% 26% 18% 4	1973
	11th to 20th	Day	50% 4 9% 19% 16% 3	1890
	21st to end	Day	56% 3 9% 19% 12%	1719
December	1st to 10th	Day	68% 3 10% 16% 3	2680
	11th to 20th	Day	64% 3 10% 17% 6%	3066
	21st to end	Day	67% 3 10% 14% 5%	4500
January	1st to 10th	Night	71% 2 8% 13% 4	7636
	11th to 20th	Night	71% 2 6% 12% 8% 1	7680
	21st to end	Night	63% 2 9% 17% 7% 1	8401
February	1st to 10th	Night	60% 4 10% 17% 10%	2730
	11th to 20th	Night	64% 3 7% 17% 9%	2612
	21st to end	Night	60% 3 9% 17% 9% 2	2060
March	1st to 10th	Night	53% 3 6% 23% 12% 2	5028
	11th to 20th	Night	43% 4 7% 28% 15% 3	5090
	21st to end	Night	51% 4 8% 21% 14% 2	5588
April	1st to 10th	Night	51% 5% 9% 20% 14% 2	2247
	11th to 20th	Night	44% 4 12% 20% 15% 5%	2003
	21st to end	Night	44% 5% 10% 22% 17% 2	1800
May	1st to 10th	Night	60% 6% 10% 12% 9% 3	4060
	11th to 20th	Night	46% 8% 12% 23% 10% 1	4033
	21st to end	Night	51% 7% 11% 21% 8% 3	4429
June	1st to 10th	Night	37% 7% 11% 26% 17% 2	1725
	11th to 20th	Night	40% 7% 13% 22% 15% 2	1601
	21st to end	Night	36% 8% 15% 22% 17% 2	1799
July	1st to 10th	Night	42% 7% 10% 24% 15% 2	4015
	11th to 20th	Night	46% 8% 15% 21% 9% 1	4006
	21st to end	Night	42% 7% 11% 20% 18% 2	4297
August	1st to 10th	Night	45% 6% 15% 25% 8% 1	2904
	11th to 20th	Night	43% 6% 9% 22% 20% 1	2902
	21st to end	Night	33% 6% 11% 31% 16% 2	3388
September	1st to 10th	Night	38% 5% 12% 18% 23% 5%	2065
	11th to 20th	Night	32% 5% 11% 26% 23% 3	2200
	21st to end	Night	44% 5% 11% 20% 20% 1	2200
October	1st to 10th	Night	32% 3 9% 27% 24% 6%	3869
	11th to 20th	Night	35% 4 8% 23% 21% 8%	3899
	21st to end	Night	35% 3 5% 28% 25% 4	4252
November	1st to 10th	Night	39% 4 10% 21% 20% 5%	2540
	11th to 20th	Night	52% 3 7% 20% 15% 3	2730
	21st to end	Night	57% 3 9% 20% 11% 1	2896
December	1st to 10th	Night	65% 3 10% 17% 4	4720
	11th to 20th	Night	65% 3 11% 16% 6%	5348
	21st to end	Night	64% 4 10% 15% 7%	6666

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	32% 29% 25% 10% 5%	330
	11th to 20th	Day	42% 25% 26% 6%	330
	21st to end	Day	37% 27% 26% 7% 2 1	363
February	1st to 10th	Day	33% 22% 33% 9% 3	330
	11th to 20th	Day	46% 23% 24% 6% 1	330
	21st to end	Day	35% 23% 35% 7%	287
March	1st to 10th	Day	35% 18% 27% 16% 4	540
	11th to 20th	Day	32% 23% 27% 13% 5% 1	540
	21st to end	Day	32% 18% 32% 14% 4	594
April	1st to 10th	Day	31% 21% 23% 19% 6% 1	540
	11th to 20th	Day	27% 18% 27% 16% 8% 3	516
	21st to end	Day	28% 17% 27% 20% 7% 2	500
May	1st to 10th	Day	26% 16% 29% 17% 8% 4	503
	11th to 20th	Day	23% 13% 28% 23% 10% 4	527
	21st to end	Day	19% 9% 26% 25% 15% 7%	573
June	1st to 10th	Day	16% 9% 24% 30% 15% 6%	530
	11th to 20th	Day	18% 6% 23% 28% 18% 6%	530
	21st to end	Day	15% 7% 27% 30% 15% 5%	530
July	1st to 10th	Day	16% 5% 19% 26% 20% 14%	525
	11th to 20th	Day	14% 4 23% 32% 19% 8%	524
	21st to end	Day	19% 5% 20% 27% 22% 8%	576
August	1st to 10th	Day	13% 5% 21% 30% 20% 10%	526
	11th to 20th	Day	14% 6% 20% 28% 21% 11%	519
	21st to end	Day	12% 3 20% 32% 22% 11%	583
September	1st to 10th	Day	15% 6% 18% 28% 22% 10%	530
	11th to 20th	Day	12% 3 15% 32% 28% 11%	530
	21st to end	Day	25% 8% 22% 28% 13% 4	530
October	1st to 10th	Day	17% 9% 24% 24% 20% 6%	530
	11th to 20th	Day	20% 14% 27% 24% 12% 2	530
	21st to end	Day	28% 16% 26% 20% 9% 1	583
November	1st to 10th	Day	20% 13% 32% 24% 9% 2	451
	11th to 20th	Day	30% 17% 31% 16% 5% 1	330
	21st to end	Day	33% 18% 33% 13% 3 1	239
December	1st to 10th	Day	32% 24% 29% 10% 4 1	220
	11th to 20th	Day	38% 20% 22% 16% 4	220
	21st to end	Day	38% 19% 26% 13% 5%	349
January	1st to 10th	Night	33% 18% 26% 19% 4	840
	11th to 20th	Night	34% 19% 27% 18% 2	840
	21st to end	Night	30% 18% 31% 18% 2	924
February	1st to 10th	Night	31% 13% 30% 25% 2	840
	11th to 20th	Night	34% 18% 30% 16% 2	823
	21st to end	Night	32% 17% 32% 18% 2	692
March	1st to 10th	Night	29% 14% 29% 25% 3	840
	11th to 20th	Night	32% 15% 28% 19% 6% 1	840
	21st to end	Night	27% 13% 33% 22% 4 1	924
April	1st to 10th	Night	28% 15% 29% 23% 6%	840
	11th to 20th	Night	21% 14% 31% 23% 11% 1	783
	21st to end	Night	18% 11% 32% 31% 8% 1	600
May	1st to 10th	Night	23% 8% 26% 31% 11% 1	600
	11th to 20th	Night	21% 6% 27% 30% 15% 1	591
	21st to end	Night	15% 3 24% 32% 22% 4	650
June	1st to 10th	Night	13% 3 24% 36% 22% 1	525
	11th to 20th	Night	13% 4 21% 38% 23% 1	401
	21st to end	Night	15% 3 17% 39% 23% 2	599
July	1st to 10th	Night	13% 2 16% 37% 27% 4	585
	11th to 20th	Night	10% 3 14% 38% 30% 5%	582
	21st to end	Night	14% 2 12% 35% 32% 3	657
August	1st to 10th	Night	11% 2 15% 39% 31% 3	597
	11th to 20th	Night	15% 2 12% 38% 29% 5%	594
	21st to end	Night	13% 2 13% 34% 32% 6%	760
September	1st to 10th	Night	14% 3 15% 36% 28% 4	800
	11th to 20th	Night	13% 3 17% 31% 33% 4	800
	21st to end	Night	20% 5% 20% 33% 20% 2	800
October	1st to 10th	Night	17% 5% 19% 31% 25% 3	800
	11th to 20th	Night	18% 10% 27% 32% 13% 1	800
	21st to end	Night	26% 9% 24% 29% 11% 1	880
November	1st to 10th	Night	17% 9% 27% 31% 15%	820
	11th to 20th	Night	31% 11% 25% 24% 8% 1	840
	21st to end	Night	28% 12% 26% 27% 7% 1	840
December	1st to 10th	Night	33% 16% 27% 20% 4	840
	11th to 20th	Night	29% 16% 28% 23% 5%	840
	21st to end	Night	31% 13% 27% 28% 2	924

Page generated at 2026-04-14 02:44:24. Version ac07

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