Cooksburg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cooksburg clear sky chart from 2005-11-06 to 2024-11-05.

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	18% 11% 4 8% 5% 4 4 4 5% 6% 30%	101272
	Night	18% 12% 5% 8% 5% 4 4 3 5% 6% 30%	97706
Transparency	Day	53% 6% 11% 19% 10% 1	104912
	Night	54% 6% 11% 18% 10% 1	102205
Seeing	Day	25% 16% 27% 19% 10% 3	14666
	Night	24% 14% 27% 24% 10% 1	24183

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% 23% 11% 13% 3 4 3 2 3 3 16%	2622
	11th to 20th	Day	12% 22% 10% 18% 8% 4 3 2 3 3 16%	2840
	21st to end	Day	26% 20% 8% 16% 6% 4 4 2 2 3 10%	3124
February	1st to 10th	Day	17% 21% 5% 13% 8% 5% 3 3 4 3 18%	1710
	11th to 20th	Day	16% 15% 6% 15% 6% 4 4 3 5% 5% 19%	1663
	21st to end	Day	21% 16% 4 11% 6% 5% 4 3 4 5% 23%	1537
March	1st to 10th	Day	21% 11% 5% 8% 5% 3 3 3 5% 6% 29%	3435
	11th to 20th	Day	13% 17% 7% 9% 5% 4 4 3 4 5% 30%	3480
	21st to end	Day	18% 12% 3 9% 5% 4 4 3 5% 6% 30%	3815
April	1st to 10th	Day	18% 15% 4 6% 5% 5% 4 3 4 7% 29%	2236
	11th to 20th	Day	19% 15% 3 7% 4 4 4 4 4 4 33%	2254
	21st to end	Day	23% 10% 3 6% 4 4 4 3 5% 6% 33%	2465
May	1st to 10th	Day	25% 9% 3 7% 5% 4 4 4 5% 6% 28%	4082
	11th to 20th	Day	22% 9% 3 8% 5% 5% 5% 4 6% 7% 27%	4205
	21st to end	Day	14% 7% 3 6% 5% 4 5% 4 6% 8% 40%	4823
June	1st to 10th	Day	17% 7% 2 7% 6% 4 5% 5% 6% 8% 33%	2660
	11th to 20th	Day	16% 7% 2 7% 6% 5% 5% 4 6% 9% 32%	2660
	21st to end	Day	18% 6% 2 6% 4 5% 4 4 8% 8% 35%	2660
July	1st to 10th	Day	11% 6% 3 7% 5% 5% 6% 5% 7% 10% 37%	4440
	11th to 20th	Day	12% 6% 2 6% 5% 5% 6% 5% 7% 8% 38%	4251
	21st to end	Day	11% 7% 2 7% 6% 5% 6% 4 6% 8% 37%	4466
August	1st to 10th	Day	19% 8% 3 8% 5% 5% 5% 4 6% 8% 29%	4104
	11th to 20th	Day	14% 7% 3 7% 5% 5% 6% 6% 7% 8% 31%	4044
	21st to end	Day	12% 6% 2 7% 4 5% 6% 5% 7% 9% 36%	4261
September	1st to 10th	Day	18% 7% 2 6% 4 4 3 4 4 6% 41%	2280
	11th to 20th	Day	14% 7% 2 7% 4 5% 5% 3 6% 6% 41%	2168
	21st to end	Day	21% 8% 4 7% 5% 4 3 3 6% 7% 32%	2047
October	1st to 10th	Day	20% 7% 2 6% 5% 5% 4 3 5% 7% 36%	1900
	11th to 20th	Day	23% 10% 3 6% 4 4 4 4 4 5% 33%	1900
	21st to end	Day	24% 12% 3 7% 4 3 5% 4 4 6% 27%	2090
November	1st to 10th	Day	12% 11% 3 8% 4 4 5% 4 5% 6% 39%	1808
	11th to 20th	Day	19% 16% 4 8% 5% 3 3 4 4 5% 27%	1520
	21st to end	Day	20% 20% 4 7% 4 5% 3 3 5% 6% 22%	1520
December	1st to 10th	Day	20% 25% 8% 11% 5% 3 4 3 3 3 15%	1520
	11th to 20th	Day	19% 21% 9% 10% 4 3 4 3 4 5% 18%	1910
	21st to end	Day	27% 25% 8% 9% 5% 4 3 2 3 4 12%	2772
January	1st to 10th	Night	17% 22% 10% 14% 5% 4 3 2 3 4 14%	4319
	11th to 20th	Night	16% 19% 9% 18% 6% 7% 5% 3 3 3 12%	4120
	21st to end	Night	27% 19% 8% 14% 4 4 3 3 3 3 13%	4532
February	1st to 10th	Night	19% 16% 6% 11% 7% 5% 5% 3 3 4 21%	2470
	11th to 20th	Night	17% 15% 6% 13% 6% 6% 5% 3 4 5% 20%	2403
	21st to end	Night	22% 13% 4 13% 6% 4 4 2 4 4 23%	1914
March	1st to 10th	Night	21% 14% 4 7% 5% 4 3 3 4 5% 30%	3418
	11th to 20th	Night	17% 16% 9% 7% 4 3 3 2 4 5% 29%	3480
	21st to end	Night	18% 10% 3 8% 4 4 4 3 4 6% 37%	3817
April	1st to 10th	Night	18% 14% 4 7% 5% 3 4 3 5% 5% 30%	1943
	11th to 20th	Night	19% 9% 3 6% 4 4 4 4 5% 6% 36%	1875
	21st to end	Night	15% 10% 4 7% 4 3 5% 4 4 9% 35%	1731
May	1st to 10th	Night	27% 9% 2 6% 4 4 4 3 4 6% 29%	2813
	11th to 20th	Night	21% 10% 3 6% 5% 4 4 4 3 6% 34%	2686
	21st to end	Night	14% 7% 2 5% 4 4 5% 4 6% 10% 41%	2732
June	1st to 10th	Night	10% 6% 3 6% 5% 6% 5% 4 6% 8% 41%	1520
	11th to 20th	Night	12% 6% 3 7% 5% 5% 5% 4 6% 8% 40%	1520
	21st to end	Night	14% 6% 3 7% 4 4 5% 3 6% 9% 40%	1520
July	1st to 10th	Night	14% 7% 3 7% 6% 4 4 4 5% 7% 39%	2520
	11th to 20th	Night	12% 5% 2 6% 5% 4 4 4 7% 9% 42%	2704
	21st to end	Night	12% 7% 3 6% 5% 4 5% 4 6% 6% 42%	3087
August	1st to 10th	Night	18% 8% 3 7% 4 5% 4 3 6% 7% 36%	2825
	11th to 20th	Night	17% 7% 2 7% 5% 4 4 4 6% 6% 40%	2785
	21st to end	Night	11% 4 2 6% 4 4 5% 4 6% 8% 46%	3348
September	1st to 10th	Night	16% 6% 2 5% 3 3 5% 4 4 6% 47%	1900
	11th to 20th	Night	12% 5% 2 5% 3 4 4 3 5% 8% 50%	2009
	21st to end	Night	20% 7% 3 7% 5% 4 4 3 5% 5% 37%	2133
October	1st to 10th	Night	17% 7% 2 6% 4 4 4 3 5% 7% 42%	2280
	11th to 20th	Night	20% 9% 2 7% 4 3 4 3 5% 6% 36%	2280
	21st to end	Night	23% 11% 3 6% 4 5% 4 3 5% 5% 31%	2508
November	1st to 10th	Night	14% 10% 3 6% 4 4 4 3 5% 6% 41%	2365
	11th to 20th	Night	18% 17% 3 8% 6% 4 4 3 5% 5% 27%	2660
	21st to end	Night	20% 17% 6% 7% 4 4 4 3 6% 6% 24%	2660
December	1st to 10th	Night	21% 21% 9% 10% 5% 5% 4 3 4 4 14%	2660
	11th to 20th	Night	19% 19% 7% 12% 6% 4 3 2 4 5% 20%	3285
	21st to end	Night	26% 20% 8% 10% 5% 4 4 3 4 4 12%	4884

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	75% 4 7% 10% 4	2623
	11th to 20th	Day	76% 3 8% 10% 4	2840
	21st to end	Day	82% 3 6% 6% 2 1	3124
February	1st to 10th	Day	72% 4 7% 11% 5%	1710
	11th to 20th	Day	67% 5% 8% 14% 6%	1672
	21st to end	Day	64% 5% 10% 15% 6% 2	1537
March	1st to 10th	Day	55% 6% 11% 23% 5%	3435
	11th to 20th	Day	55% 7% 15% 18% 5% 1	3480
	21st to end	Day	53% 6% 9% 20% 11% 1	3815
April	1st to 10th	Day	56% 5% 10% 16% 12% 1	2236
	11th to 20th	Day	53% 6% 10% 17% 12% 1	2254
	21st to end	Day	52% 6% 10% 20% 11% 2	2465
May	1st to 10th	Day	55% 7% 8% 22% 7% 1	4120
	11th to 20th	Day	54% 9% 11% 18% 7% 1	4209
	21st to end	Day	40% 8% 14% 22% 14% 2	4837
June	1st to 10th	Day	46% 8% 12% 20% 12% 1	2660
	11th to 20th	Day	46% 7% 14% 19% 12% 1	2660
	21st to end	Day	44% 7% 13% 25% 11% 1	2660
July	1st to 10th	Day	41% 7% 12% 23% 14% 2	4370
	11th to 20th	Day	41% 7% 12% 26% 14%	4177
	21st to end	Day	42% 8% 12% 22% 16% 1	4324
August	1st to 10th	Day	52% 7% 13% 20% 7%	4091
	11th to 20th	Day	45% 8% 14% 25% 8%	4083
	21st to end	Day	40% 8% 14% 27% 11% 1	4261
September	1st to 10th	Day	43% 6% 10% 22% 16% 2	2280
	11th to 20th	Day	42% 7% 11% 25% 15% 1	2168
	21st to end	Day	51% 5% 12% 20% 12%	2047
October	1st to 10th	Day	40% 5% 12% 24% 18% 1	3160
	11th to 20th	Day	46% 6% 13% 18% 13% 4	3140
	21st to end	Day	44% 4 13% 26% 12% 1	3428
November	1st to 10th	Day	45% 6% 13% 19% 15% 2	1808
	11th to 20th	Day	59% 4 10% 17% 7% 2	1520
	21st to end	Day	64% 5% 10% 15% 5% 1	1520
December	1st to 10th	Day	76% 4 9% 9% 2	1520
	11th to 20th	Day	69% 5% 10% 13% 3	1906
	21st to end	Day	78% 4 8% 8% 1	2772
January	1st to 10th	Night	75% 4 7% 11% 3	4319
	11th to 20th	Night	76% 5% 8% 8% 2	4120
	21st to end	Night	77% 4 6% 9% 3	4532
February	1st to 10th	Night	68% 5% 8% 14% 6%	2470
	11th to 20th	Night	66% 6% 8% 14% 6%	2405
	21st to end	Night	65% 4 8% 13% 9% 1	1914
March	1st to 10th	Night	57% 5% 8% 24% 5%	3418
	11th to 20th	Night	57% 6% 15% 16% 6% 1	3480
	21st to end	Night	47% 5% 9% 22% 15% 2	3817
April	1st to 10th	Night	55% 6% 10% 17% 12% 1	1943
	11th to 20th	Night	47% 7% 11% 19% 13% 2	1875
	21st to end	Night	47% 7% 11% 22% 12% 2	1731
May	1st to 10th	Night	55% 6% 10% 17% 10% 2	2840
	11th to 20th	Night	50% 8% 12% 20% 9% 1	2687
	21st to end	Night	36% 9% 14% 22% 14% 4	2739
June	1st to 10th	Night	39% 8% 12% 25% 14% 1	1520
	11th to 20th	Night	40% 10% 12% 23% 13% 2	1520
	21st to end	Night	39% 8% 14% 23% 16%	1520
July	1st to 10th	Night	45% 6% 10% 20% 17% 2	2480
	11th to 20th	Night	36% 7% 15% 25% 15% 1	2655
	21st to end	Night	41% 6% 11% 21% 21% 1	2988
August	1st to 10th	Night	46% 8% 12% 23% 10% 1	2814
	11th to 20th	Night	42% 8% 12% 29% 9% 1	2812
	21st to end	Night	34% 7% 15% 30% 12% 2	3348
September	1st to 10th	Night	38% 6% 13% 24% 17% 3	1900
	11th to 20th	Night	32% 6% 13% 27% 21% 1	2009
	21st to end	Night	49% 6% 11% 19% 14% 1	2133
October	1st to 10th	Night	40% 5% 10% 23% 21% 1	3800
	11th to 20th	Night	41% 6% 12% 20% 15% 6%	3779
	21st to end	Night	40% 4 14% 23% 17% 1	4120
November	1st to 10th	Night	43% 6% 12% 22% 13% 3	2365
	11th to 20th	Night	59% 5% 9% 17% 8% 2	2660
	21st to end	Night	61% 6% 10% 17% 4 1	2660
December	1st to 10th	Night	73% 5% 9% 9% 3	2660
	11th to 20th	Night	69% 5% 10% 13% 3	3288
	21st to end	Night	76% 6% 9% 8% 1	4884

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	35% 29% 25% 9% 2	211
	11th to 20th	Day	36% 31% 25% 5% 2 1	270
	21st to end	Day	36% 25% 31% 5% 2	297
February	1st to 10th	Day	30% 32% 29% 7% 1	270
	11th to 20th	Day	39% 27% 29% 6%	270
	21st to end	Day	41% 23% 29% 6% 1	287
March	1st to 10th	Day	32% 23% 30% 13% 3	460
	11th to 20th	Day	33% 21% 32% 10% 3 2	460
	21st to end	Day	36% 23% 25% 12% 4	506
April	1st to 10th	Day	32% 22% 25% 15% 5% 1	460
	11th to 20th	Day	28% 22% 26% 13% 8% 3	452
	21st to end	Day	30% 17% 31% 16% 5% 1	460
May	1st to 10th	Day	31% 16% 27% 17% 7% 2	463
	11th to 20th	Day	25% 15% 27% 21% 9% 3	487
	21st to end	Day	16% 12% 29% 24% 14% 5%	529
June	1st to 10th	Day	20% 13% 30% 26% 9% 2	490
	11th to 20th	Day	21% 12% 25% 25% 14% 3	490
	21st to end	Day	19% 12% 32% 23% 11% 2	490
July	1st to 10th	Day	15% 8% 24% 25% 20% 8%	485
	11th to 20th	Day	14% 8% 27% 26% 18% 7%	484
	21st to end	Day	14% 7% 30% 25% 18% 6%	532
August	1st to 10th	Day	15% 7% 24% 26% 21% 7%	486
	11th to 20th	Day	18% 6% 27% 27% 14% 9%	479
	21st to end	Day	16% 7% 24% 29% 16% 8%	539
September	1st to 10th	Day	20% 10% 20% 27% 17% 7%	490
	11th to 20th	Day	14% 5% 22% 30% 19% 10%	490
	21st to end	Day	26% 11% 24% 21% 13% 4	490
October	1st to 10th	Day	21% 12% 27% 20% 15% 5%	490
	11th to 20th	Day	28% 14% 31% 17% 8% 2	490
	21st to end	Day	32% 17% 29% 16% 6%	539
November	1st to 10th	Day	22% 18% 30% 17% 11% 2	402
	11th to 20th	Day	34% 22% 26% 13% 4 2	180
	21st to end	Day	32% 23% 35% 9% 1	180
December	1st to 10th	Day	37% 25% 26% 8% 3 2	180
	11th to 20th	Day	37% 20% 32% 8% 2 1	180
	21st to end	Day	32% 25% 32% 8% 3	198
January	1st to 10th	Night	29% 25% 31% 12% 2	760
	11th to 20th	Night	33% 21% 30% 14% 2	760
	21st to end	Night	26% 25% 31% 16% 2	836
February	1st to 10th	Night	30% 20% 30% 18% 1	760
	11th to 20th	Night	30% 24% 35% 10% 1	743
	21st to end	Night	31% 24% 30% 14% 2	628
March	1st to 10th	Night	26% 21% 34% 16% 3	760
	11th to 20th	Night	31% 19% 27% 18% 5%	760
	21st to end	Night	26% 18% 34% 17% 4 1	836
April	1st to 10th	Night	26% 17% 34% 18% 5%	760
	11th to 20th	Night	24% 16% 30% 21% 8% 1	751
	21st to end	Night	20% 12% 35% 28% 5% 1	591
May	1st to 10th	Night	25% 10% 26% 28% 11% 1	570
	11th to 20th	Night	21% 10% 29% 31% 9%	487
	21st to end	Night	13% 5% 27% 32% 20% 2	411
June	1st to 10th	Night	12% 4 32% 37% 16%	380
	11th to 20th	Night	14% 5% 24% 43% 13%	380
	21st to end	Night	15% 5% 29% 36% 14% 1	380
July	1st to 10th	Night	12% 4 21% 41% 20% 3	370
	11th to 20th	Night	13% 3 18% 37% 27% 3	473
	21st to end	Night	13% 5% 15% 43% 23% 2	624
August	1st to 10th	Night	13% 1 14% 43% 27% 2	567
	11th to 20th	Night	15% 4 14% 37% 26% 3	564
	21st to end	Night	12% 3 21% 34% 26% 4	760
September	1st to 10th	Night	19% 5% 19% 32% 21% 3	760
	11th to 20th	Night	14% 6% 16% 33% 27% 4	760
	21st to end	Night	23% 9% 22% 24% 18% 3	760
October	1st to 10th	Night	21% 8% 23% 28% 18% 2	760
	11th to 20th	Night	27% 10% 28% 24% 9% 1	760
	21st to end	Night	29% 13% 30% 24% 5%	836
November	1st to 10th	Night	20% 13% 29% 28% 9%	760
	11th to 20th	Night	28% 16% 30% 19% 6% 1	760
	21st to end	Night	30% 17% 31% 16% 4	760
December	1st to 10th	Night	35% 21% 26% 14% 4	760
	11th to 20th	Night	29% 24% 28% 15% 4	760
	21st to end	Night	32% 20% 31% 15% 2	836

Page generated at 2024-11-03 02:11:30. Version ac07

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