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 2024-01-12.

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	18% 11% 4 7% 6% 3 5% 5% 5% 6% 29%	74638
	Night	17% 11% 5% 7% 6% 3 4 4 5% 6% 31%	75078
Transparency	Day	55% 6% 11% 18% 9% 1	74349
	Night	54% 6% 11% 18% 10% 1	74886
Seeing	Day	25% 15% 27% 19% 10% 3	13518
	Night	24% 14% 27% 24% 10% 1	23174

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	18% 18% 8% 12% 8% 4 4 4 3 3 18%	1583
	11th to 20th	Day	18% 19% 7% 14% 8% 3 3 3 3 5% 17%	1629
	21st to end	Day	16% 19% 8% 14% 10% 4 5% 3 3 4 14%	1782
February	1st to 10th	Day	18% 19% 7% 12% 9% 4 4 3 4 3 17%	1620
	11th to 20th	Day	17% 14% 8% 13% 7% 3 5% 4 5% 5% 19%	1573
	21st to end	Day	21% 16% 5% 11% 7% 3 4 3 4 5% 23%	1448
March	1st to 10th	Day	17% 12% 7% 9% 7% 3 3 5% 5% 5% 27%	1980
	11th to 20th	Day	19% 14% 6% 7% 5% 3 5% 4 4 5% 27%	1980
	21st to end	Day	21% 13% 5% 8% 5% 3 3 3 4 5% 29%	2178
April	1st to 10th	Day	17% 13% 5% 6% 5% 4 4 4 4 7% 30%	2118
	11th to 20th	Day	19% 14% 4 6% 5% 3 4 4 4 4 33%	2134
	21st to end	Day	23% 10% 4 5% 4 3 3 4 5% 5% 33%	2335
May	1st to 10th	Day	19% 10% 4 7% 5% 3 6% 5% 5% 7% 29%	2340
	11th to 20th	Day	24% 8% 3 6% 6% 4 5% 4 5% 7% 29%	2369
	21st to end	Day	14% 6% 3 5% 5% 3 6% 5% 7% 8% 37%	2725
June	1st to 10th	Day	17% 6% 2 6% 6% 4 5% 5% 6% 9% 33%	2520
	11th to 20th	Day	16% 7% 3 6% 7% 3 5% 6% 5% 9% 33%	2520
	21st to end	Day	18% 5% 2 5% 5% 4 5% 5% 7% 8% 35%	2520
July	1st to 10th	Day	13% 6% 3 6% 6% 3 5% 5% 6% 9% 37%	2520
	11th to 20th	Day	13% 6% 2 6% 6% 4 6% 7% 7% 8% 35%	2415
	21st to end	Day	13% 6% 3 6% 6% 4 7% 5% 7% 9% 33%	2547
August	1st to 10th	Day	12% 6% 3 6% 6% 5% 5% 6% 7% 10% 34%	2327
	11th to 20th	Day	15% 6% 3 7% 6% 4 5% 8% 6% 7% 32%	2303
	21st to end	Day	15% 6% 3 7% 5% 4 6% 7% 7% 8% 33%	2429
September	1st to 10th	Day	19% 7% 3 6% 5% 2 4 5% 4 6% 40%	2160
	11th to 20th	Day	15% 6% 3 6% 5% 3 5% 4 6% 7% 39%	2054
	21st to end	Day	20% 8% 4 6% 6% 3 4 4 6% 7% 33%	1940
October	1st to 10th	Day	20% 7% 3 6% 5% 4 4 5% 5% 7% 34%	1800
	11th to 20th	Day	24% 9% 4 5% 5% 3 5% 4 4 5% 32%	1800
	21st to end	Day	26% 11% 4 6% 5% 2 4 5% 4 6% 26%	1980
November	1st to 10th	Day	13% 10% 3 7% 5% 3 5% 5% 5% 6% 38%	1767
	11th to 20th	Day	19% 15% 5% 7% 6% 2 3 5% 4 5% 27%	1520
	21st to end	Day	21% 19% 5% 6% 5% 3 4 4 5% 6% 22%	1520
December	1st to 10th	Day	20% 22% 10% 11% 6% 2 3 4 3 3 15%	1520
	11th to 20th	Day	19% 20% 9% 10% 5% 2 4 4 4 5% 19%	1910
	21st to end	Day	27% 23% 8% 8% 6% 3 3 2 3 4 12%	2772
January	1st to 10th	Night	19% 17% 9% 12% 7% 4 4 4 4 4 17%	2578
	11th to 20th	Night	20% 17% 8% 11% 7% 4 5% 4 4 4 16%	2360
	21st to end	Night	14% 20% 9% 10% 8% 4 5% 5% 4 5% 16%	2574
February	1st to 10th	Night	20% 15% 7% 11% 8% 5% 5% 4 3 4 19%	2340
	11th to 20th	Night	18% 14% 6% 11% 7% 5% 6% 4 4 5% 20%	2273
	21st to end	Night	22% 12% 5% 12% 7% 4 4 3 3 4 23%	1805
March	1st to 10th	Night	15% 12% 6% 9% 6% 4 4 5% 5% 6% 28%	1980
	11th to 20th	Night	19% 12% 5% 6% 6% 2 5% 3 4 6% 33%	1980
	21st to end	Night	18% 12% 4 6% 6% 3 5% 4 4 6% 32%	2178
April	1st to 10th	Night	18% 12% 5% 7% 5% 2 4 5% 5% 6% 31%	1841
	11th to 20th	Night	18% 9% 3 5% 5% 3 4 5% 5% 7% 36%	1775
	21st to end	Night	16% 10% 5% 6% 4 2 5% 4 4 9% 34%	1640
May	1st to 10th	Night	19% 8% 3 7% 6% 3 5% 5% 5% 7% 33%	1620
	11th to 20th	Night	17% 9% 3 5% 5% 3 4 5% 4 7% 37%	1522
	21st to end	Night	12% 5% 2 5% 6% 3 5% 5% 6% 9% 42%	1550
June	1st to 10th	Night	11% 6% 3 5% 5% 3 6% 5% 6% 8% 42%	1440
	11th to 20th	Night	13% 5% 3 6% 6% 4 5% 5% 5% 8% 39%	1440
	21st to end	Night	13% 5% 3 6% 5% 3 4 4 6% 9% 41%	1440
July	1st to 10th	Night	11% 5% 3 6% 6% 4 5% 5% 5% 6% 45%	1440
	11th to 20th	Night	11% 4 3 4 5% 2 4 5% 6% 9% 46%	1540
	21st to end	Night	12% 5% 2 5% 5% 3 5% 6% 7% 9% 41%	1771
August	1st to 10th	Night	10% 5% 2 6% 4 3 4 5% 7% 9% 45%	1611
	11th to 20th	Night	13% 6% 2 5% 6% 3 4 5% 7% 7% 43%	1598
	21st to end	Night	12% 4 2 5% 5% 3 5% 6% 6% 8% 45%	1908
September	1st to 10th	Night	16% 6% 2 5% 4 2 5% 5% 4 6% 46%	1800
	11th to 20th	Night	12% 5% 2 4 4 2 4 4 6% 8% 49%	1903
	21st to end	Night	19% 7% 3 5% 6% 3 4 5% 5% 6% 38%	2020
October	1st to 10th	Night	17% 7% 2 5% 4 4 4 4 5% 8% 41%	2160
	11th to 20th	Night	21% 8% 2 6% 5% 2 4 4 5% 6% 35%	2160
	21st to end	Night	25% 11% 3 5% 5% 4 4 5% 5% 5% 29%	2376
November	1st to 10th	Night	14% 10% 3 5% 5% 3 4 5% 5% 6% 41%	2306
	11th to 20th	Night	19% 15% 4 7% 7% 3 4 4 4 5% 27%	2660
	21st to end	Night	20% 16% 6% 7% 5% 3 4 4 5% 6% 24%	2660
December	1st to 10th	Night	21% 19% 10% 10% 6% 3 5% 4 4 4 15%	2660
	11th to 20th	Night	19% 19% 7% 11% 7% 3 4 3 3 5% 20%	3285
	21st to end	Night	26% 19% 8% 9% 6% 3 4 4 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	73% 4 9% 10% 4	1584
	11th to 20th	Day	73% 4 10% 9% 4	1629
	21st to end	Day	76% 3 7% 9% 4 1	1782
February	1st to 10th	Day	74% 4 8% 10% 5%	1620
	11th to 20th	Day	68% 5% 8% 13% 6%	1582
	21st to end	Day	65% 4 10% 14% 6% 2	1448
March	1st to 10th	Day	57% 6% 11% 18% 7%	1980
	11th to 20th	Day	59% 5% 9% 17% 8% 2	1980
	21st to end	Day	59% 4 8% 18% 10% 2	2178
April	1st to 10th	Day	55% 4 11% 17% 12% 1	2118
	11th to 20th	Day	53% 5% 10% 17% 13% 2	2134
	21st to end	Day	53% 5% 10% 19% 11% 2	2335
May	1st to 10th	Day	53% 7% 10% 18% 10% 2	2340
	11th to 20th	Day	55% 6% 9% 16% 11% 2	2373
	21st to end	Day	43% 8% 17% 21% 10% 1	2725
June	1st to 10th	Day	47% 8% 12% 20% 12% 1	2520
	11th to 20th	Day	47% 7% 14% 19% 12% 1	2520
	21st to end	Day	44% 7% 12% 25% 11% 1	2520
July	1st to 10th	Day	43% 8% 12% 22% 13% 2	2450
	11th to 20th	Day	43% 8% 13% 22% 13%	2341
	21st to end	Day	44% 9% 12% 20% 13% 1	2405
August	1st to 10th	Day	44% 9% 15% 25% 7%	2314
	11th to 20th	Day	46% 10% 15% 19% 9% 1	2303
	21st to end	Day	44% 9% 12% 20% 12% 2	2429
September	1st to 10th	Day	45% 7% 10% 21% 15% 2	2160
	11th to 20th	Day	42% 7% 11% 25% 14% 1	2054
	21st to end	Day	49% 6% 12% 21% 12%	1940
October	1st to 10th	Day	48% 6% 13% 18% 14% 1	1800
	11th to 20th	Day	53% 6% 12% 20% 8%	1800
	21st to end	Day	59% 5% 12% 15% 8% 1	1980
November	1st to 10th	Day	46% 7% 13% 18% 15% 2	1767
	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	72% 5% 7% 12% 4	2578
	11th to 20th	Night	72% 5% 10% 10% 2 1	2360
	21st to end	Night	69% 6% 9% 10% 5% 1	2574
February	1st to 10th	Night	70% 5% 8% 12% 5%	2340
	11th to 20th	Night	67% 5% 8% 13% 6%	2275
	21st to end	Night	66% 4 8% 13% 9%	1805
March	1st to 10th	Night	57% 7% 7% 20% 9% 1	1980
	11th to 20th	Night	55% 4 11% 19% 9% 1	1980
	21st to end	Night	54% 5% 7% 17% 14% 2	2178
April	1st to 10th	Night	54% 6% 10% 17% 12% 1	1841
	11th to 20th	Night	47% 7% 10% 19% 14% 2	1775
	21st to end	Night	47% 7% 11% 21% 11% 2	1640
May	1st to 10th	Night	50% 7% 10% 18% 12% 3	1620
	11th to 20th	Night	46% 7% 11% 20% 14% 2	1523
	21st to end	Night	37% 8% 16% 23% 14% 2	1551
June	1st to 10th	Night	38% 8% 13% 25% 14% 1	1440
	11th to 20th	Night	41% 10% 11% 22% 14% 1	1440
	21st to end	Night	38% 8% 14% 24% 16%	1440
July	1st to 10th	Night	40% 8% 10% 22% 18% 3	1400
	11th to 20th	Night	33% 8% 15% 23% 19% 2	1491
	21st to end	Night	37% 8% 14% 23% 17% 1	1672
August	1st to 10th	Night	33% 9% 16% 28% 14% 1	1600
	11th to 20th	Night	38% 10% 14% 26% 12% 1	1598
	21st to end	Night	35% 9% 15% 24% 14% 3	1908
September	1st to 10th	Night	39% 6% 13% 24% 16% 3	1800
	11th to 20th	Night	32% 7% 14% 27% 20% 1	1903
	21st to end	Night	46% 7% 11% 20% 15% 1	2020
October	1st to 10th	Night	43% 6% 15% 21% 15% 2	2160
	11th to 20th	Night	48% 6% 13% 20% 11% 1	2160
	21st to end	Night	56% 5% 11% 18% 9% 1	2376
November	1st to 10th	Night	43% 6% 12% 22% 13% 3	2306
	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	34% 29% 25% 9% 2	211
	11th to 20th	Day	34% 32% 26% 5% 2 1	243
	21st to end	Day	34% 27% 31% 5% 2	264
February	1st to 10th	Day	32% 33% 31% 3	240
	11th to 20th	Day	40% 27% 28% 5%	240
	21st to end	Day	41% 23% 29% 6% 1	256
March	1st to 10th	Day	32% 23% 30% 12% 2	420
	11th to 20th	Day	33% 20% 33% 10% 3 2	420
	21st to end	Day	36% 22% 25% 12% 5%	462
April	1st to 10th	Day	32% 23% 24% 15% 5% 1	420
	11th to 20th	Day	27% 21% 27% 14% 8% 3	412
	21st to end	Day	30% 18% 30% 17% 4 1	420
May	1st to 10th	Day	30% 17% 27% 16% 7% 2	423
	11th to 20th	Day	26% 14% 27% 21% 9% 2	447
	21st to end	Day	15% 12% 30% 23% 14% 6%	485
June	1st to 10th	Day	19% 12% 30% 27% 9% 2	450
	11th to 20th	Day	22% 13% 24% 23% 15% 3	450
	21st to end	Day	19% 11% 32% 24% 12% 2	450
July	1st to 10th	Day	16% 7% 23% 25% 21% 8%	445
	11th to 20th	Day	14% 7% 27% 28% 18% 6%	444
	21st to end	Day	15% 7% 30% 24% 17% 6%	488
August	1st to 10th	Day	13% 6% 25% 26% 23% 8%	446
	11th to 20th	Day	16% 6% 27% 27% 15% 10%	439
	21st to end	Day	17% 7% 24% 29% 15% 8%	495
September	1st to 10th	Day	20% 9% 19% 28% 16% 7%	450
	11th to 20th	Day	15% 5% 23% 29% 19% 10%	450
	21st to end	Day	23% 10% 26% 22% 14% 4	450
October	1st to 10th	Day	21% 12% 27% 20% 15% 6%	450
	11th to 20th	Day	29% 14% 32% 17% 7% 1	450
	21st to end	Day	34% 17% 29% 15% 5%	495
November	1st to 10th	Day	23% 18% 28% 17% 11% 2	385
	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	30% 25% 31% 12% 2	760
	11th to 20th	Night	33% 21% 31% 14% 2	727
	21st to end	Night	25% 25% 32% 16% 2	792
February	1st to 10th	Night	31% 21% 30% 16% 1	720
	11th to 20th	Night	31% 23% 35% 10% 1	703
	21st to end	Night	31% 24% 30% 14% 1	592
March	1st to 10th	Night	26% 21% 34% 16% 3	720
	11th to 20th	Night	31% 18% 27% 18% 5%	720
	21st to end	Night	26% 17% 34% 17% 4 1	792
April	1st to 10th	Night	26% 18% 33% 18% 5%	720
	11th to 20th	Night	23% 16% 31% 20% 9% 1	711
	21st to end	Night	21% 12% 35% 26% 5% 1	560
May	1st to 10th	Night	24% 10% 26% 29% 11% 1	540
	11th to 20th	Night	20% 10% 30% 31% 9%	461
	21st to end	Night	13% 6% 28% 31% 20% 2	389
June	1st to 10th	Night	12% 4 31% 38% 15%	360
	11th to 20th	Night	15% 5% 24% 43% 13%	360
	21st to end	Night	14% 4 30% 37% 14%	360
July	1st to 10th	Night	11% 3 21% 41% 21% 3	350
	11th to 20th	Night	13% 3 18% 37% 26% 3	447
	21st to end	Night	13% 5% 15% 43% 23% 2	591
August	1st to 10th	Night	12% 1 14% 43% 28% 1	537
	11th to 20th	Night	15% 3 14% 38% 27% 4	534
	21st to end	Night	13% 3 21% 33% 26% 4	720
September	1st to 10th	Night	19% 5% 19% 33% 21% 3	720
	11th to 20th	Night	14% 6% 17% 33% 25% 4	720
	21st to end	Night	22% 9% 23% 25% 18% 4	720
October	1st to 10th	Night	20% 8% 23% 29% 17% 2	720
	11th to 20th	Night	28% 10% 28% 25% 8% 1	720
	21st to end	Night	30% 13% 29% 23% 4 1	792
November	1st to 10th	Night	20% 13% 29% 28% 10%	740
	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 2024-01-09 07:14:39. Version ac07

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