Edja Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Edja Lake clear sky chart from 2005-11-06 to 2024-03-06.

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% 6% 3 5% 4 5% 6% 30%	78330
	Night	17% 12% 5% 8% 6% 3 4 4 5% 6% 30%	81173
Transparency	Day	55% 6% 11% 18% 9% 1	78035
	Night	55% 6% 11% 18% 8% 1	81002
Seeing	Day	24% 16% 30% 20% 9% 2	13440
	Night	24% 12% 28% 26% 10% 1	22702

By Month

Percentage Cloud Cover NE (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	16% 19% 8% 14% 9% 3 4 3 2 3 18%	2517
	11th to 20th	Day	14% 13% 6% 17% 9% 4 4 3 3 4 22%	2520
	21st to end	Day	14% 18% 8% 12% 8% 4 5% 4 3 4 18%	2850
February	1st to 10th	Day	13% 16% 6% 12% 9% 4 4 5% 4 5% 22%	1710
	11th to 20th	Day	13% 16% 6% 11% 7% 3 4 3 4 5% 27%	1663
	21st to end	Day	17% 16% 5% 8% 7% 4 5% 3 4 5% 27%	1551
March	1st to 10th	Day	16% 14% 5% 9% 7% 4 5% 4 4 6% 27%	1850
	11th to 20th	Day	14% 13% 6% 9% 7% 4 6% 4 4 4 28%	1980
	21st to end	Day	18% 9% 4 6% 6% 3 4 4 4 5% 36%	2290
April	1st to 10th	Day	23% 13% 4 8% 6% 3 3 3 4 4 30%	2160
	11th to 20th	Day	22% 10% 4 6% 5% 2 3 4 4 5% 34%	2134
	21st to end	Day	23% 11% 4 7% 5% 3 4 4 4 5% 31%	2330
May	1st to 10th	Day	20% 9% 3 6% 6% 3 4 3 4 7% 34%	2520
	11th to 20th	Day	19% 7% 3 6% 6% 3 5% 4 5% 6% 35%	2478
	21st to end	Day	16% 7% 3 6% 6% 3 5% 5% 5% 7% 36%	2725
June	1st to 10th	Day	20% 8% 3 8% 6% 4 6% 5% 5% 7% 28%	2520
	11th to 20th	Day	16% 6% 2 5% 5% 3 5% 5% 7% 8% 38%	2520
	21st to end	Day	18% 7% 3 7% 8% 4 6% 5% 6% 7% 30%	2520
July	1st to 10th	Day	13% 6% 3 5% 6% 3 5% 6% 6% 9% 37%	2520
	11th to 20th	Day	12% 7% 3 6% 6% 4 6% 5% 6% 9% 36%	2520
	21st to end	Day	11% 7% 3 6% 7% 4 6% 6% 7% 9% 35%	2744
August	1st to 10th	Day	12% 7% 2 7% 7% 4 6% 6% 8% 8% 33%	2489
	11th to 20th	Day	13% 7% 3 6% 6% 4 6% 5% 5% 7% 38%	2303
	21st to end	Day	15% 6% 3 7% 5% 4 5% 5% 6% 8% 37%	2376
September	1st to 10th	Day	15% 6% 3 6% 6% 3 4 5% 5% 7% 41%	2160
	11th to 20th	Day	14% 7% 3 5% 6% 3 4 4 5% 6% 42%	2160
	21st to end	Day	20% 7% 2 5% 6% 3 4 4 5% 8% 35%	1916
October	1st to 10th	Day	20% 9% 2 7% 6% 3 4 4 4 7% 34%	1800
	11th to 20th	Day	25% 11% 4 7% 6% 3 4 3 5% 6% 25%	1800
	21st to end	Day	27% 11% 2 8% 5% 3 4 4 5% 6% 24%	1828
November	1st to 10th	Day	16% 12% 5% 7% 5% 3 4 5% 5% 7% 33%	1638
	11th to 20th	Day	19% 13% 6% 9% 8% 3 5% 5% 5% 5% 22%	1520
	21st to end	Day	24% 16% 6% 11% 5% 3 4 4 3 4 18%	1520
December	1st to 10th	Day	23% 19% 6% 9% 6% 4 3 4 4 5% 15%	1520
	11th to 20th	Day	20% 16% 7% 10% 6% 4 6% 4 5% 4 18%	1906
	21st to end	Day	27% 20% 6% 12% 5% 2 3 2 2 3 18%	2772
January	1st to 10th	Night	16% 19% 6% 12% 7% 3 4 4 4 4 20%	4429
	11th to 20th	Night	14% 14% 6% 13% 9% 3 5% 5% 4 5% 23%	4440
	21st to end	Night	13% 18% 8% 11% 9% 5% 5% 4 3 4 20%	4788
February	1st to 10th	Night	12% 15% 7% 11% 9% 4 6% 5% 4 5% 22%	2470
	11th to 20th	Night	13% 14% 5% 11% 8% 4 5% 6% 4 4 25%	2403
	21st to end	Night	14% 15% 6% 9% 8% 4 4 4 6% 6% 26%	1903
March	1st to 10th	Night	17% 14% 6% 8% 8% 4 5% 3 5% 4 26%	2212
	11th to 20th	Night	15% 15% 5% 7% 6% 3 4 4 5% 5% 31%	1979
	21st to end	Night	15% 11% 4 7% 5% 2 4 4 4 5% 39%	2066
April	1st to 10th	Night	22% 10% 4 7% 5% 3 4 4 5% 6% 30%	1800
	11th to 20th	Night	19% 9% 3 4 6% 3 3 5% 5% 6% 38%	1775
	21st to end	Night	22% 10% 3 7% 6% 3 4 3 3 5% 33%	1645
May	1st to 10th	Night	20% 9% 3 6% 4 2 4 4 4 7% 36%	1440
	11th to 20th	Night	19% 6% 3 6% 4 3 5% 4 5% 6% 38%	1415
	21st to end	Night	14% 6% 3 6% 5% 3 5% 5% 6% 8% 39%	1550
June	1st to 10th	Night	18% 7% 2 5% 5% 3 4 5% 7% 8% 34%	1440
	11th to 20th	Night	15% 7% 3 6% 5% 3 4 5% 5% 7% 40%	1440
	21st to end	Night	16% 6% 3 6% 6% 4 5% 4 5% 8% 37%	1440
July	1st to 10th	Night	11% 5% 2 6% 4 3 6% 5% 7% 8% 43%	1440
	11th to 20th	Night	12% 6% 4 5% 5% 3 5% 6% 6% 8% 42%	1440
	21st to end	Night	9% 5% 2 6% 5% 4 5% 5% 7% 10% 43%	1574
August	1st to 10th	Night	10% 5% 3 5% 6% 4 6% 6% 6% 9% 40%	1447
	11th to 20th	Night	11% 6% 2 4 5% 4 5% 5% 5% 10% 44%	1598
	21st to end	Night	14% 5% 2 5% 4 3 5% 5% 7% 8% 42%	1962
September	1st to 10th	Night	13% 6% 3 6% 4 3 5% 4 6% 6% 45%	1800
	11th to 20th	Night	16% 5% 3 5% 4 2 3 4 5% 8% 45%	1800
	21st to end	Night	19% 6% 3 7% 5% 2 4 3 4 7% 40%	2042
October	1st to 10th	Night	21% 8% 3 5% 4 3 3 4 5% 6% 38%	2160
	11th to 20th	Night	23% 10% 4 7% 6% 3 5% 3 4 6% 28%	2160
	21st to end	Night	25% 10% 4 6% 6% 4 5% 4 5% 6% 26%	2526
November	1st to 10th	Night	18% 11% 4 8% 6% 4 4 4 4 6% 30%	2437
	11th to 20th	Night	19% 12% 4 9% 8% 3 5% 5% 4 5% 26%	2660
	21st to end	Night	23% 16% 5% 9% 7% 3 4 4 5% 5% 19%	2660
December	1st to 10th	Night	21% 19% 7% 10% 7% 3 5% 4 4 4 17%	2660
	11th to 20th	Night	21% 15% 6% 9% 6% 3 3 4 3 5% 23%	3288
	21st to end	Night	25% 21% 6% 11% 6% 3 3 3 3 3 18%	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	70% 6% 9% 10% 4	2518
	11th to 20th	Day	67% 5% 8% 13% 6%	2520
	21st to end	Day	69% 6% 9% 10% 5% 1	2850
February	1st to 10th	Day	65% 5% 9% 14% 6% 1	1710
	11th to 20th	Day	62% 4 12% 13% 9% 1	1672
	21st to end	Day	62% 4 9% 14% 10% 1	1551
March	1st to 10th	Day	60% 4 9% 15% 10% 1	1853
	11th to 20th	Day	60% 4 10% 14% 10% 3	1980
	21st to end	Day	51% 5% 8% 19% 13% 4	2290
April	1st to 10th	Day	59% 3 7% 17% 10% 3	2160
	11th to 20th	Day	52% 4 8% 22% 12% 2	2134
	21st to end	Day	56% 5% 7% 16% 12% 3	2330
May	1st to 10th	Day	52% 5% 8% 19% 13% 3	2520
	11th to 20th	Day	49% 6% 8% 18% 17% 2	2482
	21st to end	Day	47% 7% 12% 18% 14% 2	2725
June	1st to 10th	Day	54% 6% 11% 17% 10% 1	2520
	11th to 20th	Day	43% 7% 11% 25% 11% 2	2520
	21st to end	Day	51% 9% 12% 19% 9%	2520
July	1st to 10th	Day	41% 8% 14% 25% 11%	2450
	11th to 20th	Day	42% 8% 15% 24% 10% 1	2445
	21st to end	Day	44% 9% 15% 24% 9%	2591
August	1st to 10th	Day	46% 9% 16% 22% 7%	2475
	11th to 20th	Day	44% 8% 15% 25% 7% 1	2303
	21st to end	Day	43% 9% 15% 23% 11% 1	2376
September	1st to 10th	Day	41% 7% 14% 26% 12%	2160
	11th to 20th	Day	42% 7% 13% 28% 10% 1	2160
	21st to end	Day	46% 8% 14% 25% 7%	1916
October	1st to 10th	Day	50% 7% 12% 21% 10%	1800
	11th to 20th	Day	60% 8% 13% 15% 4 1	1800
	21st to end	Day	61% 6% 13% 14% 6% 1	1828
November	1st to 10th	Day	50% 7% 13% 23% 6% 1	1638
	11th to 20th	Day	63% 7% 12% 12% 6%	1520
	21st to end	Day	71% 5% 10% 8% 5%	1520
December	1st to 10th	Day	72% 6% 10% 9% 3	1520
	11th to 20th	Day	65% 8% 9% 12% 6%	1906
	21st to end	Day	74% 3 5% 15% 3	2772
January	1st to 10th	Night	67% 7% 15% 9% 2	4429
	11th to 20th	Night	62% 7% 14% 12% 5%	4440
	21st to end	Night	68% 6% 9% 9% 7%	4788
February	1st to 10th	Night	64% 5% 9% 15% 6% 1	2470
	11th to 20th	Night	61% 5% 9% 17% 6% 1	2405
	21st to end	Night	58% 5% 10% 18% 9% 1	1903
March	1st to 10th	Night	60% 5% 8% 17% 8% 2	2222
	11th to 20th	Night	56% 5% 9% 17% 10% 2	1980
	21st to end	Night	48% 5% 8% 21% 14% 4	2066
April	1st to 10th	Night	54% 5% 10% 16% 13% 2	1800
	11th to 20th	Night	48% 4 9% 23% 14% 2	1775
	21st to end	Night	54% 4 8% 17% 14% 3	1645
May	1st to 10th	Night	49% 5% 7% 20% 16% 4	1440
	11th to 20th	Night	45% 7% 9% 20% 16% 4	1416
	21st to end	Night	42% 7% 12% 20% 16% 2	1551
June	1st to 10th	Night	46% 8% 15% 21% 9% 1	1440
	11th to 20th	Night	42% 7% 13% 24% 12% 2	1440
	21st to end	Night	46% 9% 12% 21% 12%	1440
July	1st to 10th	Night	36% 7% 17% 25% 14% 1	1400
	11th to 20th	Night	38% 8% 13% 29% 12% 1	1392
	21st to end	Night	35% 11% 18% 26% 10%	1486
August	1st to 10th	Night	38% 11% 17% 25% 10%	1437
	11th to 20th	Night	36% 9% 19% 25% 10%	1598
	21st to end	Night	38% 9% 17% 27% 9%	1962
September	1st to 10th	Night	39% 8% 13% 28% 12% 1	1800
	11th to 20th	Night	38% 6% 15% 32% 8% 1	1800
	21st to end	Night	44% 6% 13% 29% 8%	2042
October	1st to 10th	Night	47% 8% 11% 23% 11%	2160
	11th to 20th	Night	57% 6% 12% 18% 6% 1	2160
	21st to end	Night	59% 7% 12% 16% 6%	2526
November	1st to 10th	Night	55% 7% 13% 18% 7%	2437
	11th to 20th	Night	60% 6% 11% 15% 7% 1	2660
	21st to end	Night	67% 7% 11% 13% 2	2660
December	1st to 10th	Night	71% 5% 10% 10% 3	2660
	11th to 20th	Night	64% 5% 9% 14% 7%	3288
	21st to end	Night	73% 4 6% 13% 4	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	22% 21% 35% 18% 4 1	180
	11th to 20th	Day	30% 13% 35% 16% 6% 1	180
	21st to end	Day	21% 18% 33% 20% 7%	222
February	1st to 10th	Day	27% 26% 35% 9% 4	270
	11th to 20th	Day	26% 29% 36% 9% 1	270
	21st to end	Day	31% 20% 34% 13% 1	363
March	1st to 10th	Day	24% 20% 35% 17% 4	440
	11th to 20th	Day	26% 19% 32% 18% 4 1	420
	21st to end	Day	31% 18% 29% 16% 6% 1	462
April	1st to 10th	Day	32% 17% 28% 16% 7%	420
	11th to 20th	Day	34% 18% 20% 15% 10% 3	412
	21st to end	Day	31% 20% 28% 13% 6% 1	420
May	1st to 10th	Day	28% 15% 31% 17% 7% 2	423
	11th to 20th	Day	24% 18% 32% 17% 7% 2	447
	21st to end	Day	22% 18% 29% 20% 8% 2	485
June	1st to 10th	Day	24% 13% 34% 21% 6% 2	450
	11th to 20th	Day	19% 16% 29% 22% 12% 2	450
	21st to end	Day	18% 13% 32% 24% 11% 2	450
July	1st to 10th	Day	13% 8% 32% 35% 9% 2	445
	11th to 20th	Day	14% 11% 35% 26% 13% 2	444
	21st to end	Day	13% 9% 33% 30% 14% 2	488
August	1st to 10th	Day	17% 7% 29% 30% 15% 3	446
	11th to 20th	Day	17% 7% 27% 25% 16% 8%	439
	21st to end	Day	16% 14% 30% 20% 13% 7%	495
September	1st to 10th	Day	17% 13% 27% 22% 14% 7%	450
	11th to 20th	Day	16% 13% 26% 21% 16% 8%	450
	21st to end	Day	21% 13% 27% 20% 13% 7%	450
October	1st to 10th	Day	26% 15% 24% 20% 12% 4	450
	11th to 20th	Day	31% 20% 27% 14% 6% 2	450
	21st to end	Day	33% 14% 29% 18% 6%	419
November	1st to 10th	Day	27% 17% 28% 22% 5% 1	332
	11th to 20th	Day	29% 19% 33% 12% 5% 1	180
	21st to end	Day	32% 22% 30% 12% 2 1	180
December	1st to 10th	Day	30% 16% 35% 16% 3 1	180
	11th to 20th	Day	29% 26% 32% 9% 3 1	180
	21st to end	Day	31% 18% 31% 15% 5% 1	198
January	1st to 10th	Night	29% 14% 33% 19% 5%	760
	11th to 20th	Night	31% 14% 25% 23% 6%	760
	21st to end	Night	18% 12% 33% 28% 8% 1	836
February	1st to 10th	Night	21% 16% 36% 23% 5%	760
	11th to 20th	Night	23% 16% 36% 20% 4	743
	21st to end	Night	23% 18% 29% 25% 4	628
March	1st to 10th	Night	24% 18% 29% 24% 4	743
	11th to 20th	Night	24% 16% 31% 22% 7%	720
	21st to end	Night	22% 15% 29% 26% 9%	792
April	1st to 10th	Night	27% 16% 25% 27% 5%	720
	11th to 20th	Night	25% 16% 26% 23% 9%	711
	21st to end	Night	27% 14% 25% 25% 9% 1	565
May	1st to 10th	Night	26% 9% 32% 23% 11% 1	360
	11th to 20th	Night	22% 10% 28% 32% 8%	354
	21st to end	Night	16% 8% 37% 29% 10%	389
June	1st to 10th	Night	17% 9% 34% 34% 6% 1	360
	11th to 20th	Night	18% 9% 24% 34% 13% 1	360
	21st to end	Night	18% 6% 26% 36% 14%	360
July	1st to 10th	Night	11% 6% 26% 42% 16%	350
	11th to 20th	Night	13% 5% 21% 42% 18%	348
	21st to end	Night	11% 6% 25% 40% 17% 2	394
August	1st to 10th	Night	10% 6% 24% 37% 22% 1	373
	11th to 20th	Night	13% 3 17% 39% 25% 2	534
	21st to end	Night	16% 7% 25% 31% 19% 2	774
September	1st to 10th	Night	17% 5% 27% 31% 19% 1	720
	11th to 20th	Night	19% 7% 23% 31% 18% 3	720
	21st to end	Night	21% 9% 24% 27% 18% 2	720
October	1st to 10th	Night	26% 10% 26% 23% 13% 2	720
	11th to 20th	Night	30% 12% 28% 21% 8% 2	720
	21st to end	Night	30% 12% 28% 23% 6%	792
November	1st to 10th	Night	28% 16% 25% 24% 6% 1	740
	11th to 20th	Night	26% 16% 29% 19% 9% 1	760
	21st to end	Night	34% 14% 26% 21% 5%	760
December	1st to 10th	Night	32% 15% 28% 19% 5%	760
	11th to 20th	Night	27% 16% 30% 20% 5% 1	760
	21st to end	Night	34% 15% 27% 20% 3 1	836

Page generated at 2024-03-03 06:28:54. Version ac07

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