Skunk Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Skunk Bay clear sky chart from 2005-11-06 to 2024-11-11.

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	15% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	105625
	Night	17% 10% 3 8% 5% 5% 5% 4 5% 6% 32%	102122
Transparency	Day	27% 47% 8% 11% 5% 1	105380
	Night	30% 47% 7% 10% 4 1	102013
Seeing	Day	18% 10% 21% 26% 19% 5%	15221
	Night	21% 10% 20% 26% 20% 4	23533

By Month

Percentage Cloud Cover NW (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	22% 16% 5% 12% 7% 6% 6% 4 5% 5% 12%	2219
	11th to 20th	Day	18% 11% 4 9% 7% 5% 5% 4 7% 9% 22%	2418
	21st to end	Day	22% 15% 5% 12% 7% 7% 5% 4 5% 6% 13%	2872
February	1st to 10th	Day	19% 15% 4 8% 6% 5% 5% 5% 6% 8% 18%	1710
	11th to 20th	Day	17% 13% 4 10% 7% 5% 5% 5% 6% 7% 21%	1665
	21st to end	Day	16% 13% 3 10% 7% 5% 6% 4 5% 6% 24%	1460
March	1st to 10th	Day	12% 11% 3 9% 7% 8% 7% 6% 8% 9% 21%	3230
	11th to 20th	Day	14% 9% 3 7% 5% 5% 5% 4 5% 6% 38%	3490
	21st to end	Day	17% 10% 4 11% 7% 6% 6% 5% 6% 7% 21%	3938
April	1st to 10th	Day	18% 13% 3 9% 7% 6% 5% 4 6% 7% 21%	2280
	11th to 20th	Day	17% 11% 4 7% 6% 5% 5% 4 6% 7% 28%	2297
	21st to end	Day	18% 10% 3 7% 5% 6% 5% 5% 6% 8% 26%	2508
May	1st to 10th	Day	17% 7% 3 6% 4 4 4 3 5% 7% 40%	4420
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 6% 8% 40%	4377
	21st to end	Day	26% 10% 4 8% 5% 5% 5% 4 5% 6% 23%	4813
June	1st to 10th	Day	19% 8% 2 7% 5% 5% 5% 4 6% 7% 30%	2763
	11th to 20th	Day	18% 9% 4 9% 6% 6% 6% 5% 6% 7% 25%	2850
	21st to end	Day	12% 6% 3 7% 5% 4 5% 4 7% 8% 40%	2850
July	1st to 10th	Day	7% 4 2 4 2 3 3 2 4 5% 65%	4740
	11th to 20th	Day	5% 4 1 4 3 3 3 3 5% 5% 65%	4622
	21st to end	Day	12% 5% 2 5% 3 3 3 3 5% 6% 54%	4790
August	1st to 10th	Day	5% 4 1 4 2 3 4 3 5% 7% 61%	4318
	11th to 20th	Day	9% 8% 3 8% 4 4 4 4 6% 8% 42%	4026
	21st to end	Day	14% 8% 3 7% 4 4 4 3 4 5% 44%	4353
September	1st to 10th	Day	10% 5% 2 5% 3 3 4 3 5% 8% 52%	2280
	11th to 20th	Day	11% 8% 4 7% 5% 4 4 3 6% 6% 41%	2280
	21st to end	Day	13% 7% 2 7% 5% 5% 5% 4 7% 7% 40%	2004
October	1st to 10th	Day	13% 7% 3 8% 4 5% 6% 5% 7% 9% 34%	3180
	11th to 20th	Day	21% 10% 4 10% 5% 5% 4 3 5% 6% 26%	3161
	21st to end	Day	16% 12% 5% 12% 7% 6% 6% 4 6% 7% 20%	3264
November	1st to 10th	Day	21% 12% 4 11% 6% 5% 4 5% 6% 6% 18%	1587
	11th to 20th	Day	20% 11% 4 11% 6% 5% 5% 4 6% 6% 23%	1520
	21st to end	Day	23% 10% 4 10% 6% 3 5% 4 6% 8% 20%	1520
December	1st to 10th	Day	16% 14% 3 10% 6% 5% 5% 4 6% 6% 24%	1520
	11th to 20th	Day	16% 14% 5% 15% 8% 7% 6% 4 5% 6% 12%	1858
	21st to end	Day	17% 15% 6% 13% 7% 7% 6% 3 5% 6% 14%	2442
January	1st to 10th	Night	21% 17% 5% 10% 7% 6% 6% 4 6% 5% 14%	4726
	11th to 20th	Night	19% 12% 4 9% 5% 4 4 4 6% 9% 25%	4477
	21st to end	Night	25% 13% 4 9% 6% 5% 6% 4 7% 6% 15%	4773
February	1st to 10th	Night	20% 15% 4 9% 6% 4 5% 4 6% 7% 21%	2470
	11th to 20th	Night	16% 14% 4 10% 6% 5% 5% 4 5% 5% 26%	2402
	21st to end	Night	17% 15% 3 9% 6% 5% 5% 4 6% 6% 25%	1994
March	1st to 10th	Night	13% 14% 4 10% 7% 6% 7% 6% 6% 7% 20%	3630
	11th to 20th	Night	12% 9% 3 6% 4 4 4 4 6% 7% 42%	3489
	21st to end	Night	21% 14% 4 9% 6% 5% 6% 3 5% 5% 21%	3715
April	1st to 10th	Night	18% 13% 3 9% 6% 6% 6% 6% 6% 7% 21%	1900
	11th to 20th	Night	17% 10% 3 7% 5% 6% 5% 4 5% 6% 32%	1832
	21st to end	Night	20% 10% 3 8% 5% 5% 4 4 6% 8% 27%	1672
May	1st to 10th	Night	15% 8% 3 5% 3 4 4 3 4 6% 45%	2540
	11th to 20th	Night	16% 6% 2 5% 4 4 3 3 4 7% 45%	2516
	21st to end	Night	28% 10% 3 7% 5% 4 4 3 4 5% 26%	2762
June	1st to 10th	Night	21% 7% 3 7% 6% 4 5% 4 6% 6% 33%	1414
	11th to 20th	Night	22% 9% 3 8% 5% 5% 5% 3 5% 7% 28%	1330
	21st to end	Night	12% 5% 1 6% 4 4 4 5% 7% 6% 44%	1330
July	1st to 10th	Night	11% 4 2 3 2 2 3 2 4 4 64%	2220
	11th to 20th	Night	5% 2 1 2 2 2 2 2 4 6% 72%	2338
	21st to end	Night	16% 5% 1 4 3 3 3 3 4 6% 53%	2762
August	1st to 10th	Night	5% 3 1 3 3 3 3 3 4 5% 68%	2613
	11th to 20th	Night	12% 6% 3 7% 4 3 3 3 4 6% 49%	2812
	21st to end	Night	15% 7% 2 6% 3 3 3 3 4 5% 49%	3306
September	1st to 10th	Night	8% 5% 2 5% 3 3 3 3 4 6% 57%	1900
	11th to 20th	Night	14% 7% 3 7% 5% 4 4 3 6% 6% 42%	1900
	21st to end	Night	14% 7% 3 7% 4 4 4 3 6% 6% 43%	2174
October	1st to 10th	Night	13% 7% 3 7% 4 5% 5% 4 6% 8% 38%	3800
	11th to 20th	Night	20% 10% 3 7% 4 5% 4 4 5% 7% 32%	3777
	21st to end	Night	20% 11% 3 9% 5% 5% 5% 3 5% 6% 27%	4299
November	1st to 10th	Night	23% 11% 3 7% 5% 5% 5% 4 6% 6% 26%	2709
	11th to 20th	Night	19% 11% 4 8% 6% 6% 4 4 5% 6% 26%	2666
	21st to end	Night	17% 13% 4 8% 7% 5% 6% 4 6% 6% 23%	2660
December	1st to 10th	Night	19% 12% 4 8% 5% 5% 5% 4 5% 6% 25%	2660
	11th to 20th	Night	18% 14% 5% 12% 7% 5% 5% 4 6% 6% 17%	3340
	21st to end	Night	20% 16% 5% 11% 7% 6% 5% 4 6% 6% 15%	5214

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% 38% 6% 5% 1	2219
	11th to 20th	Day	36% 41% 7% 15% 2	2442
	21st to end	Day	50% 40% 6% 3	2872
February	1st to 10th	Day	25% 67% 3 2 2 1	1710
	11th to 20th	Day	26% 66% 2 3 2	1674
	21st to end	Day	22% 67% 3 5% 3	1460
March	1st to 10th	Day	34% 42% 12% 8% 3	3230
	11th to 20th	Day	23% 42% 11% 21% 2	3490
	21st to end	Day	37% 43% 11% 7% 1	3938
April	1st to 10th	Day	21% 67% 6% 5%	2280
	11th to 20th	Day	18% 68% 6% 6% 2 1	2297
	21st to end	Day	19% 67% 5% 6% 2	2508
May	1st to 10th	Day	24% 42% 8% 18% 7% 1	4420
	11th to 20th	Day	25% 42% 17% 13% 3	4380
	21st to end	Day	39% 42% 13% 5% 1	4814
June	1st to 10th	Day	15% 67% 8% 7% 3	2763
	11th to 20th	Day	18% 66% 6% 7% 3	2850
	21st to end	Day	15% 65% 9% 8% 2	2850
July	1st to 10th	Day	11% 36% 3 17% 20% 12%	4666
	11th to 20th	Day	9% 38% 6% 19% 26% 2	4541
	21st to end	Day	22% 36% 15% 20% 7% 1	4639
August	1st to 10th	Day	12% 37% 7% 29% 14% 1	4301
	11th to 20th	Day	30% 38% 15% 13% 4 1	4065
	21st to end	Day	30% 38% 6% 18% 7%	4352
September	1st to 10th	Day	17% 61% 8% 7% 6% 1	2280
	11th to 20th	Day	19% 63% 6% 5% 6%	2280
	21st to end	Day	18% 62% 8% 8% 4	2004
October	1st to 10th	Day	30% 39% 14% 15% 2	3180
	11th to 20th	Day	42% 38% 7% 9% 4	3161
	21st to end	Day	42% 38% 8% 8% 4 1	3264
November	1st to 10th	Day	31% 58% 6% 4 1	1587
	11th to 20th	Day	23% 61% 5% 5% 3 2	1520
	21st to end	Day	23% 62% 4 6% 5%	1520
December	1st to 10th	Day	26% 61% 2 8% 3	1520
	11th to 20th	Day	40% 51% 4 4 1	1861
	21st to end	Day	49% 37% 9% 3 1	2442
January	1st to 10th	Night	47% 40% 5% 5% 2	4726
	11th to 20th	Night	33% 42% 8% 15% 2	4515
	21st to end	Night	50% 40% 7% 3 1	4773
February	1st to 10th	Night	23% 66% 4 3 3 1	2470
	11th to 20th	Night	26% 65% 3 4 2	2404
	21st to end	Night	21% 66% 5% 5% 3	1994
March	1st to 10th	Night	41% 42% 7% 7% 3	3630
	11th to 20th	Night	20% 41% 14% 23% 1 1	3490
	21st to end	Night	43% 41% 9% 7% 1	3715
April	1st to 10th	Night	21% 67% 5% 6%	1900
	11th to 20th	Night	20% 67% 5% 5% 3 1	1832
	21st to end	Night	22% 66% 4 4 3	1672
May	1st to 10th	Night	23% 41% 7% 20% 8% 1	2540
	11th to 20th	Night	25% 40% 16% 14% 4	2516
	21st to end	Night	39% 45% 10% 4 1	2762
June	1st to 10th	Night	16% 67% 8% 7% 2	1414
	11th to 20th	Night	19% 66% 5% 7% 2	1330
	21st to end	Night	16% 65% 9% 7% 2	1330
July	1st to 10th	Night	14% 36% 3 16% 18% 13%	2185
	11th to 20th	Night	7% 36% 4 19% 32% 1	2296
	21st to end	Night	26% 37% 9% 18% 10% 1	2674
August	1st to 10th	Night	11% 37% 6% 30% 15% 1	2605
	11th to 20th	Night	30% 38% 14% 13% 4 1	2839
	21st to end	Night	28% 37% 8% 19% 8% 1	3306
September	1st to 10th	Night	17% 60% 8% 8% 5% 1	1900
	11th to 20th	Night	21% 61% 4 6% 6% 1	1900
	21st to end	Night	18% 61% 5% 11% 3	2174
October	1st to 10th	Night	28% 38% 13% 19% 2	3800
	11th to 20th	Night	37% 38% 8% 14% 3	3777
	21st to end	Night	42% 38% 8% 8% 4 1	4299
November	1st to 10th	Night	28% 57% 7% 7% 1	2709
	11th to 20th	Night	24% 61% 4 5% 3 2	2666
	21st to end	Night	23% 63% 4 4 6%	2660
December	1st to 10th	Night	27% 61% 3 7% 3	2660
	11th to 20th	Night	36% 51% 7% 4 2	3336
	21st to end	Night	46% 38% 8% 6% 2	5214

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	28% 15% 24% 18% 11% 3	180
	11th to 20th	Day	27% 17% 28% 10% 17% 2	180
	21st to end	Day	32% 16% 24% 17% 8% 3	250
February	1st to 10th	Day	28% 18% 24% 18% 11% 1	370
	11th to 20th	Day	30% 15% 25% 21% 8% 2	365
	21st to end	Day	22% 20% 26% 19% 12% 1	330
March	1st to 10th	Day	22% 17% 26% 22% 11% 1	460
	11th to 20th	Day	23% 17% 19% 22% 14% 6%	460
	21st to end	Day	21% 17% 29% 20% 10% 2	506
April	1st to 10th	Day	22% 16% 23% 23% 12% 3	460
	11th to 20th	Day	17% 17% 31% 19% 11% 4	452
	21st to end	Day	20% 12% 27% 26% 13% 2	460
May	1st to 10th	Day	14% 7% 26% 33% 17% 3	463
	11th to 20th	Day	17% 6% 20% 31% 18% 9%	488
	21st to end	Day	20% 8% 17% 29% 18% 9%	529
June	1st to 10th	Day	18% 8% 24% 29% 17% 4	593
	11th to 20th	Day	17% 7% 25% 31% 17% 3	680
	21st to end	Day	12% 5% 20% 35% 22% 6%	680
July	1st to 10th	Day	10% 4 19% 33% 28% 7%	671
	11th to 20th	Day	6% 5% 16% 32% 32% 9%	602
	21st to end	Day	8% 3 11% 32% 35% 11%	531
August	1st to 10th	Day	7% 3 10% 31% 35% 14%	487
	11th to 20th	Day	5% 2 11% 35% 34% 13%	477
	21st to end	Day	12% 4 17% 34% 25% 8%	539
September	1st to 10th	Day	13% 6% 18% 33% 25% 5%	490
	11th to 20th	Day	15% 7% 18% 28% 28% 4	490
	21st to end	Day	16% 9% 23% 29% 20% 3	490
October	1st to 10th	Day	20% 9% 22% 23% 21% 6%	490
	11th to 20th	Day	23% 12% 22% 21% 17% 4	490
	21st to end	Day	24% 19% 19% 23% 12% 2	430
November	1st to 10th	Day	35% 11% 24% 19% 10%	210
	11th to 20th	Day	26% 18% 24% 13% 11% 7%	180
	21st to end	Day	27% 14% 26% 16% 9% 8%	180
December	1st to 10th	Day	26% 18% 20% 14% 15% 7%	180
	11th to 20th	Day	28% 22% 27% 15% 6% 2	180
	21st to end	Day	27% 18% 27% 20% 6% 2	198
January	1st to 10th	Night	29% 14% 25% 18% 12% 3	850
	11th to 20th	Night	27% 14% 19% 20% 19% 2	786
	21st to end	Night	26% 12% 20% 23% 16% 3	836
February	1st to 10th	Night	27% 13% 23% 24% 11% 3	760
	11th to 20th	Night	22% 12% 23% 24% 17% 1	744
	21st to end	Night	24% 13% 24% 23% 13% 3	628
March	1st to 10th	Night	21% 14% 24% 25% 14% 2	760
	11th to 20th	Night	22% 16% 21% 24% 15% 2	760
	21st to end	Night	22% 12% 26% 26% 11% 2	836
April	1st to 10th	Night	24% 8% 22% 28% 16% 2	760
	11th to 20th	Night	20% 9% 24% 27% 17% 3	704
	21st to end	Night	22% 7% 22% 33% 14% 2	532
May	1st to 10th	Night	15% 7% 22% 34% 19% 4	380
	11th to 20th	Night	18% 3 17% 28% 31% 3	374
	21st to end	Night	22% 7% 14% 29% 23% 5%	411
June	1st to 10th	Night	21% 5% 20% 32% 20% 2	380
	11th to 20th	Night	19% 10% 18% 32% 19% 2	380
	21st to end	Night	14% 3 15% 37% 27% 3	380
July	1st to 10th	Night	12% 3 11% 31% 39% 5%	370
	11th to 20th	Night	8% 3 13% 34% 39% 4	368
	21st to end	Night	9% 3 7% 33% 43% 6%	416
August	1st to 10th	Night	10% 1 6% 26% 47% 9%	423
	11th to 20th	Night	8% 2 6% 27% 46% 11%	564
	21st to end	Night	11% 4 13% 33% 36% 4	722
September	1st to 10th	Night	11% 2 10% 37% 33% 7%	760
	11th to 20th	Night	16% 3 13% 23% 33% 11%	760
	21st to end	Night	15% 5% 19% 29% 26% 5%	760
October	1st to 10th	Night	15% 7% 18% 29% 26% 6%	760
	11th to 20th	Night	21% 8% 18% 25% 22% 5%	760
	21st to end	Night	23% 10% 22% 26% 16% 3	836
November	1st to 10th	Night	27% 13% 22% 25% 13% 1	780
	11th to 20th	Night	25% 13% 24% 22% 14% 3	762
	21st to end	Night	24% 14% 22% 21% 14% 4	760
December	1st to 10th	Night	23% 11% 22% 25% 16% 3	760
	11th to 20th	Night	26% 17% 24% 21% 11% 2	776
	21st to end	Night	31% 16% 25% 19% 9% 1	935

Page generated at 2024-11-08 03:44:49. Version ac07

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