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 2026-09-14.

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% 11% 4 9% 5% 5% 5% 4 6% 7% 30%	149752
	Night	16% 12% 4 10% 6% 5% 4 3 5% 6% 29%	141279
Transparency	Day	54% 4 11% 21% 9% 1	153219
	Night	56% 4 11% 19% 9% 1	145901
Seeing	Day	24% 15% 30% 20% 8% 2	16722
	Night	23% 12% 28% 26% 10% 1	25718

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	12% 18% 7% 18% 7% 5% 5% 3 4 4 16%	4661
	11th to 20th	Day	10% 21% 7% 18% 8% 4 3 3 3 4 18%	4650
	21st to end	Day	7% 14% 8% 16% 8% 7% 6% 4 5% 6% 19%	5286
February	1st to 10th	Day	12% 16% 6% 15% 8% 5% 3 4 5% 5% 22%	1890
	11th to 20th	Day	12% 17% 6% 13% 6% 4 4 2 4 5% 26%	1843
	21st to end	Day	16% 17% 5% 9% 7% 5% 4 3 4 5% 25%	1709
March	1st to 10th	Day	17% 16% 4 11% 6% 4 4 3 4 5% 23%	4593
	11th to 20th	Day	12% 15% 6% 10% 6% 5% 5% 4 5% 6% 27%	5090
	21st to end	Day	16% 12% 3 8% 6% 4 4 3 4 5% 35%	5885
April	1st to 10th	Day	22% 14% 3 8% 5% 4 3 3 3 4 31%	2520
	11th to 20th	Day	23% 12% 3 7% 5% 3 3 3 4 5% 33%	2494
	21st to end	Day	21% 11% 4 8% 4 4 4 3 4 5% 31%	2719
May	1st to 10th	Day	18% 10% 3 8% 5% 6% 6% 4 6% 8% 26%	8237
	11th to 20th	Day	17% 8% 3 8% 5% 5% 5% 4 6% 8% 31%	8221
	21st to end	Day	19% 9% 3 7% 5% 4 4 3 5% 6% 34%	9060
June	1st to 10th	Day	20% 8% 3 8% 5% 5% 5% 4 6% 6% 29%	2940
	11th to 20th	Day	15% 6% 2 6% 5% 5% 5% 4 8% 8% 36%	2940
	21st to end	Day	18% 7% 2 7% 7% 5% 5% 4 6% 7% 30%	2940
July	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 5% 8% 9% 35%	8280
	11th to 20th	Day	10% 5% 2 6% 4 5% 5% 4 7% 9% 42%	8280
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 4 7% 11% 38%	8993
August	1st to 10th	Day	15% 7% 3 9% 6% 5% 6% 4 7% 7% 31%	6423
	11th to 20th	Day	15% 7% 2 7% 5% 5% 6% 4 7% 8% 34%	5937
	21st to end	Day	12% 6% 3 8% 5% 5% 6% 5% 7% 10% 34%	6080
September	1st to 10th	Day	15% 6% 2 6% 4 4 4 4 5% 7% 41%	2520
	11th to 20th	Day	13% 7% 2 6% 4 4 4 3 5% 7% 44%	2436
	21st to end	Day	20% 7% 2 6% 5% 4 4 3 5% 8% 36%	2127
October	1st to 10th	Day	19% 9% 2 8% 4 4 4 4 4 7% 36%	2000
	11th to 20th	Day	23% 12% 3 8% 5% 5% 4 3 5% 5% 27%	2000
	21st to end	Day	25% 12% 3 10% 4 4 4 4 5% 6% 25%	2030
November	1st to 10th	Day	16% 14% 4 8% 5% 4 4 4 5% 6% 31%	1814
	11th to 20th	Day	18% 15% 5% 12% 7% 5% 4 4 5% 4 21%	1680
	21st to end	Day	24% 18% 6% 13% 5% 4 5% 3 3 4 16%	1680
December	1st to 10th	Day	20% 23% 8% 11% 6% 5% 4 3 4 4 12%	2680
	11th to 20th	Day	17% 17% 7% 13% 6% 5% 5% 3 4 4 20%	3066
	21st to end	Day	21% 19% 4 13% 5% 4 5% 3 3 4 18%	4048
January	1st to 10th	Night	12% 20% 7% 16% 7% 5% 4 3 4 4 18%	8234
	11th to 20th	Night	12% 19% 7% 17% 8% 5% 4 3 4 4 17%	8235
	21st to end	Night	7% 16% 8% 14% 8% 8% 6% 4 4 6% 19%	8877
February	1st to 10th	Night	11% 16% 6% 13% 8% 6% 5% 3 4 5% 23%	2730
	11th to 20th	Night	13% 15% 5% 13% 6% 6% 5% 4 4 4 25%	2663
	21st to end	Night	12% 16% 5% 11% 7% 5% 3 3 6% 5% 26%	2096
March	1st to 10th	Night	20% 17% 4 9% 5% 4 4 2 4 4 26%	5465
	11th to 20th	Night	12% 14% 5% 11% 6% 5% 5% 4 6% 7% 25%	5089
	21st to end	Night	15% 12% 4 10% 5% 4 4 3 5% 6% 32%	5289
April	1st to 10th	Night	22% 11% 3 8% 5% 4 3 3 5% 6% 30%	2100
	11th to 20th	Night	19% 11% 3 5% 5% 4 4 4 5% 6% 36%	2075
	21st to end	Night	22% 10% 2 7% 5% 4 3 3 4 5% 35%	1917
May	1st to 10th	Night	19% 11% 4 9% 5% 5% 5% 4 6% 7% 25%	4660
	11th to 20th	Night	15% 8% 3 8% 5% 5% 5% 4 6% 7% 34%	4639
	21st to end	Night	19% 8% 3 7% 5% 5% 5% 4 5% 6% 33%	5114
June	1st to 10th	Night	17% 8% 2 6% 5% 4 4 4 7% 8% 34%	1680
	11th to 20th	Night	15% 7% 2 7% 5% 4 5% 4 5% 7% 40%	1680
	21st to end	Night	17% 7% 2 8% 6% 5% 4 4 5% 8% 35%	1680
July	1st to 10th	Night	11% 6% 2 7% 5% 5% 6% 5% 8% 9% 36%	4680
	11th to 20th	Night	10% 6% 2 6% 4 4 5% 4 6% 8% 45%	4680
	21st to end	Night	12% 7% 3 8% 5% 4 4 4 6% 7% 41%	5084
August	1st to 10th	Night	14% 6% 2 7% 4 5% 5% 5% 6% 8% 37%	3710
	11th to 20th	Night	15% 7% 2 6% 4 5% 5% 4 6% 8% 38%	4095
	21st to end	Night	14% 7% 3 8% 5% 4 5% 4 7% 8% 37%	4999
September	1st to 10th	Night	13% 6% 3 7% 4 4 4 3 6% 6% 44%	2100
	11th to 20th	Night	15% 6% 2 5% 3 3 3 3 5% 8% 48%	2031
	21st to end	Night	18% 7% 2 7% 4 4 4 3 4 7% 40%	2270
October	1st to 10th	Night	19% 8% 2 6% 4 4 3 3 5% 6% 40%	2400
	11th to 20th	Night	21% 10% 3 8% 6% 5% 4 3 4 6% 30%	2400
	21st to end	Night	23% 10% 4 8% 5% 5% 4 3 5% 6% 27%	2808
November	1st to 10th	Night	18% 12% 4 10% 5% 5% 4 3 4 6% 29%	2701
	11th to 20th	Night	18% 13% 4 11% 6% 5% 5% 4 4 5% 26%	2940
	21st to end	Night	22% 17% 5% 10% 6% 4 4 4 5% 4 18%	2940
December	1st to 10th	Night	18% 19% 6% 14% 7% 5% 5% 4 5% 4 12%	4720
	11th to 20th	Night	21% 15% 5% 11% 5% 4 4 3 4 6% 23%	5348
	21st to end	Night	23% 20% 5% 12% 5% 4 3 2 4 4 19%	7150

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	72% 3 7% 14% 4	4662
	11th to 20th	Day	73% 3 5% 10% 9%	4680
	21st to end	Day	67% 3 8% 11% 10% 1	5286
February	1st to 10th	Day	65% 5% 8% 15% 6% 1	1890
	11th to 20th	Day	62% 3 11% 14% 9% 1	1852
	21st to end	Day	63% 4 8% 14% 10% 1	1709
March	1st to 10th	Day	64% 4 7% 11% 12% 2	4596
	11th to 20th	Day	58% 4 15% 14% 9% 1	5090
	21st to end	Day	52% 4 6% 20% 15% 2	5885
April	1st to 10th	Day	58% 3 8% 17% 11% 2	2520
	11th to 20th	Day	54% 4 7% 21% 12% 2	2494
	21st to end	Day	55% 5% 7% 17% 13% 3	2719
May	1st to 10th	Day	56% 4 8% 21% 9% 2	8249
	11th to 20th	Day	50% 5% 13% 23% 9% 1	8225
	21st to end	Day	51% 4 9% 21% 13% 1	9061
June	1st to 10th	Day	54% 6% 10% 18% 11% 1	2940
	11th to 20th	Day	44% 6% 11% 26% 11% 2	2940
	21st to end	Day	51% 8% 12% 20% 9%	2940
July	1st to 10th	Day	45% 3 15% 26% 11%	8210
	11th to 20th	Day	38% 3 15% 33% 10% 1	8205
	21st to end	Day	41% 3 16% 32% 8%	8795
August	1st to 10th	Day	52% 4 14% 21% 8%	6409
	11th to 20th	Day	48% 4 16% 27% 6%	5976
	21st to end	Day	45% 4 17% 24% 9% 1	6080
September	1st to 10th	Day	42% 6% 14% 27% 12%	2520
	11th to 20th	Day	39% 6% 13% 30% 11% 1	2436
	21st to end	Day	46% 7% 14% 23% 10%	2127
October	1st to 10th	Day	52% 4 10% 28% 7%	3260
	11th to 20th	Day	54% 6% 13% 21% 6% 1	3240
	21st to end	Day	57% 4 18% 15% 5%	3255
November	1st to 10th	Day	53% 6% 12% 22% 6% 1	1814
	11th to 20th	Day	64% 6% 11% 12% 6%	1680
	21st to end	Day	73% 5% 10% 8% 5%	1680
December	1st to 10th	Day	77% 3 8% 10% 2	2680
	11th to 20th	Day	67% 5% 7% 14% 7%	3066
	21st to end	Day	73% 3 5% 16% 3	4048
January	1st to 10th	Night	71% 4 10% 12% 3	8234
	11th to 20th	Night	72% 4 8% 11% 5%	8280
	21st to end	Night	68% 3 6% 11% 11%	8877
February	1st to 10th	Night	64% 5% 9% 16% 7% 1	2730
	11th to 20th	Night	62% 5% 9% 18% 6% 1	2665
	21st to end	Night	59% 5% 9% 18% 8% 1	2096
March	1st to 10th	Night	62% 3 8% 12% 11% 3	5475
	11th to 20th	Night	57% 5% 13% 15% 7% 2	5090
	21st to end	Night	52% 4 8% 22% 11% 2	5289
April	1st to 10th	Night	55% 5% 10% 16% 13% 2	2100
	11th to 20th	Night	49% 4 9% 23% 14% 2	2075
	21st to end	Night	52% 4 8% 18% 16% 2	1917
May	1st to 10th	Night	57% 5% 8% 21% 8% 2	4666
	11th to 20th	Night	48% 6% 12% 21% 11% 1	4640
	21st to end	Night	52% 4 9% 21% 13% 1	5115
June	1st to 10th	Night	46% 7% 13% 21% 11% 1	1680
	11th to 20th	Night	42% 6% 12% 26% 12% 2	1680
	21st to end	Night	47% 8% 11% 22% 12%	1680
July	1st to 10th	Night	44% 3 18% 24% 11% 1	4640
	11th to 20th	Night	38% 3 15% 33% 11%	4632
	21st to end	Night	43% 4 12% 32% 9%	4967
August	1st to 10th	Night	46% 5% 14% 24% 10% 1	3700
	11th to 20th	Night	45% 3 17% 27% 7%	4122
	21st to end	Night	46% 4 15% 24% 10% 1	4999
September	1st to 10th	Night	39% 6% 13% 29% 11%	2100
	11th to 20th	Night	36% 6% 15% 34% 9%	2031
	21st to end	Night	44% 6% 13% 27% 10%	2270
October	1st to 10th	Night	44% 4 13% 28% 11%	3920
	11th to 20th	Night	51% 4 14% 23% 7% 1	3899
	21st to end	Night	55% 4 16% 16% 9%	4533
November	1st to 10th	Night	56% 6% 12% 18% 7%	2701
	11th to 20th	Night	61% 6% 11% 15% 7% 1	2940
	21st to end	Night	68% 6% 11% 13% 2	2940
December	1st to 10th	Night	76% 3 10% 9% 2	4720
	11th to 20th	Night	64% 4 7% 13% 11%	5348
	21st to end	Night	71% 3 5% 13% 9%	7150

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	21% 19% 37% 19% 4	220
	11th to 20th	Day	30% 13% 37% 14% 5% 1	220
	21st to end	Day	20% 18% 35% 22% 6%	272
February	1st to 10th	Day	25% 25% 33% 12% 5%	330
	11th to 20th	Day	25% 28% 36% 10% 1	330
	21st to end	Day	29% 19% 36% 15% 2	425
March	1st to 10th	Day	24% 21% 34% 16% 4	540
	11th to 20th	Day	29% 19% 31% 17% 4 1	540
	21st to end	Day	30% 18% 31% 15% 5% 1	594
April	1st to 10th	Day	34% 19% 25% 15% 6% 1	540
	11th to 20th	Day	36% 18% 20% 14% 9% 3	532
	21st to end	Day	31% 20% 29% 13% 6% 1	540
May	1st to 10th	Day	27% 15% 33% 16% 6% 2	543
	11th to 20th	Day	24% 16% 32% 18% 8% 2	567
	21st to end	Day	25% 18% 29% 20% 7% 2	617
June	1st to 10th	Day	25% 12% 34% 20% 8% 2	570
	11th to 20th	Day	19% 17% 31% 21% 10% 2	570
	21st to end	Day	19% 14% 34% 22% 10% 2	570
July	1st to 10th	Day	14% 8% 33% 32% 10% 2	565
	11th to 20th	Day	14% 11% 35% 26% 12% 2	564
	21st to end	Day	14% 9% 32% 29% 15% 2	620
August	1st to 10th	Day	16% 6% 27% 33% 15% 3	566
	11th to 20th	Day	18% 6% 27% 26% 15% 7%	559
	21st to end	Day	15% 13% 31% 21% 13% 7%	627
September	1st to 10th	Day	18% 13% 28% 22% 13% 6%	570
	11th to 20th	Day	14% 12% 23% 22% 19% 11%	542
	21st to end	Day	21% 12% 26% 19% 15% 7%	530
October	1st to 10th	Day	25% 14% 25% 21% 12% 4	530
	11th to 20th	Day	29% 21% 27% 15% 6% 1	530
	21st to end	Day	31% 14% 29% 20% 6%	489
November	1st to 10th	Day	28% 18% 29% 20% 5% 1	388
	11th to 20th	Day	28% 19% 32% 12% 7% 1	220
	21st to end	Day	34% 22% 30% 12% 2 1	220
December	1st to 10th	Day	28% 15% 36% 17% 3	220
	11th to 20th	Day	29% 24% 32% 11% 3	220
	21st to end	Day	30% 18% 32% 15% 5%	242
January	1st to 10th	Night	28% 13% 33% 21% 5%	840
	11th to 20th	Night	31% 15% 25% 23% 6%	840
	21st to end	Night	18% 12% 34% 28% 8% 1	924
February	1st to 10th	Night	20% 15% 35% 24% 5%	840
	11th to 20th	Night	22% 16% 37% 20% 5%	823
	21st to end	Night	23% 17% 29% 26% 5%	692
March	1st to 10th	Night	25% 19% 29% 24% 4	840
	11th to 20th	Night	25% 16% 30% 23% 6%	840
	21st to end	Night	23% 15% 30% 24% 8%	924
April	1st to 10th	Night	27% 16% 26% 26% 5%	840
	11th to 20th	Night	26% 15% 26% 23% 9%	831
	21st to end	Night	28% 13% 26% 24% 9%	657
May	1st to 10th	Night	25% 10% 30% 23% 10%	420
	11th to 20th	Night	21% 10% 29% 30% 8%	414
	21st to end	Night	18% 9% 35% 29% 9%	455
June	1st to 10th	Night	17% 8% 33% 35% 6%	420
	11th to 20th	Night	18% 10% 25% 34% 12% 1	420
	21st to end	Night	19% 5% 25% 37% 14%	420
July	1st to 10th	Night	11% 5% 25% 43% 14%	410
	11th to 20th	Night	13% 5% 22% 42% 17%	408
	21st to end	Night	12% 5% 25% 41% 16% 2	460
August	1st to 10th	Night	10% 6% 23% 40% 21% 1	436
	11th to 20th	Night	14% 3 17% 39% 25% 2	624
	21st to end	Night	16% 7% 25% 31% 19% 2	903
September	1st to 10th	Night	18% 5% 27% 31% 18% 1	840
	11th to 20th	Night	18% 6% 22% 30% 21% 3	813
	21st to end	Night	21% 8% 23% 28% 19% 1	800
October	1st to 10th	Night	24% 9% 28% 24% 14% 2	800
	11th to 20th	Night	28% 12% 29% 22% 8% 1	800
	21st to end	Night	30% 12% 28% 24% 6%	880
November	1st to 10th	Night	29% 16% 25% 24% 6% 1	820
	11th to 20th	Night	27% 15% 28% 20% 9% 1	840
	21st to end	Night	34% 13% 26% 21% 5%	840
December	1st to 10th	Night	30% 15% 29% 20% 5%	840
	11th to 20th	Night	27% 16% 31% 20% 5% 1	840
	21st to end	Night	34% 15% 26% 21% 4 1	924

Page generated at 2026-09-11 04:11:58. Version ac07

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