Eagle Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eagle Lake clear sky chart from 2005-11-06 to 2024-04-03.

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	4 7% 3 5% 5% 3 4 4 5% 6% 54%	78879
	Night	4 7% 3 5% 5% 3 4 4 5% 7% 52%	81258
Transparency	Day	29% 5% 10% 20% 21% 15%	78586
	Night	30% 6% 13% 21% 19% 11%	81072
Seeing	Day	10% 14% 24% 28% 18% 5%	14107
	Night	8% 8% 18% 38% 25% 4	23495

By Month

Percentage Cloud Cover SW (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	3 13% 5% 10% 8% 4 7% 5% 5% 7% 31%	2539
	11th to 20th	Day	4 13% 6% 11% 8% 4 6% 5% 6% 8% 30%	2586
	21st to end	Day	6% 15% 5% 9% 8% 4 5% 5% 6% 6% 31%	3146
February	1st to 10th	Day	6% 9% 4 6% 5% 2 6% 5% 7% 8% 43%	1710
	11th to 20th	Day	3 9% 4 7% 6% 4 5% 5% 5% 8% 45%	1766
	21st to end	Day	4 9% 4 8% 6% 4 5% 5% 7% 7% 42%	1570
March	1st to 10th	Day	6% 12% 4 9% 7% 4 6% 5% 6% 7% 34%	1914
	11th to 20th	Day	6% 11% 5% 7% 5% 3 4 5% 5% 8% 41%	2090
	21st to end	Day	5% 13% 5% 6% 6% 3 5% 5% 5% 7% 40%	2411
April	1st to 10th	Day	6% 9% 4 9% 6% 3 4 5% 6% 7% 42%	2185
	11th to 20th	Day	6% 8% 3 6% 5% 3 5% 5% 5% 7% 47%	2129
	21st to end	Day	5% 8% 2 5% 4 3 5% 4 5% 5% 53%	2160
May	1st to 10th	Day	3 5% 3 5% 4 3 4 4 4 8% 57%	2338
	11th to 20th	Day	5% 6% 3 5% 5% 3 4 4 5% 7% 52%	2477
	21st to end	Day	7% 7% 3 7% 6% 3 5% 5% 5% 7% 45%	2723
June	1st to 10th	Day	5% 4 3 4 5% 3 6% 5% 6% 8% 51%	2520
	11th to 20th	Day	3 3 2 4 3 2 3 4 4 6% 67%	2520
	21st to end	Day	2 2 1 3 3 2 3 3 2 4 75%	2520
July	1st to 10th	Day	1 1 1 2 2 2 3 3 4 5% 75%	2520
	11th to 20th	Day	1 1 1 1 2 1 2 2 3 4 81%	2520
	21st to end	Day	2 1 1 2 2 2 3 4 5% 5% 74%	2683
August	1st to 10th	Day	2 2 1 2 3 2 3 3 5% 5% 72%	2328
	11th to 20th	Day	1 1 2 2 1 2 3 3 4 80%	2183
	21st to end	Day	1 1 1 1 1 1 1 2 3 3 85%	2376
September	1st to 10th	Day	3 1 1 2 1 2 2 2 3 82%	2160
	11th to 20th	Day	2 2 1 3 3 2 3 4 4 6% 70%	2160
	21st to end	Day	3 3 1 3 3 1 2 3 4 6% 72%	1949
October	1st to 10th	Day	5% 4 2 3 3 3 4 2 3 6% 65%	1800
	11th to 20th	Day	3 4 2 4 4 2 2 4 4 5% 66%	1800
	21st to end	Day	5% 4 1 4 4 2 4 4 5% 6% 61%	1949
November	1st to 10th	Day	8% 6% 3 5% 4 3 4 5% 5% 7% 48%	1674
	11th to 20th	Day	5% 7% 3 5% 4 4 6% 5% 6% 10% 46%	1710
	21st to end	Day	2 7% 3 5% 7% 3 5% 5% 6% 7% 50%	1521
December	1st to 10th	Day	6% 9% 4 8% 5% 3 4 4 5% 9% 42%	1520
	11th to 20th	Day	8% 15% 4 9% 7% 4 7% 6% 7% 7% 26%	1928
	21st to end	Day	4 8% 5% 9% 7% 4 5% 7% 8% 10% 33%	2794
January	1st to 10th	Night	3 9% 3 8% 7% 5% 6% 7% 7% 9% 35%	4406
	11th to 20th	Night	3 14% 5% 8% 9% 5% 6% 5% 6% 8% 30%	4358
	21st to end	Night	9% 18% 5% 7% 7% 4 5% 4 5% 7% 30%	4521
February	1st to 10th	Night	4 9% 3 7% 5% 3 4 5% 6% 8% 45%	2470
	11th to 20th	Night	3 8% 3 6% 6% 3 5% 5% 6% 8% 47%	2300
	21st to end	Night	3 8% 4 7% 5% 5% 5% 5% 5% 8% 45%	1884
March	1st to 10th	Night	5% 13% 4 7% 6% 3 5% 5% 5% 8% 38%	2261
	11th to 20th	Night	5% 11% 3 6% 5% 3 4 4 6% 10% 44%	2090
	21st to end	Night	5% 11% 4 7% 5% 3 5% 5% 6% 7% 43%	2185
April	1st to 10th	Night	3 7% 3 6% 6% 3 5% 6% 6% 9% 45%	1820
	11th to 20th	Night	6% 7% 3 5% 4 4 4 4 5% 7% 51%	1779
	21st to end	Night	4 6% 2 3 4 3 4 4 5% 8% 57%	1800
May	1st to 10th	Night	6% 5% 2 4 4 2 3 4 4 6% 62%	1617
	11th to 20th	Night	5% 5% 2 5% 5% 3 4 6% 6% 6% 53%	1416
	21st to end	Night	6% 6% 3 6% 5% 3 4 3 5% 7% 52%	1552
June	1st to 10th	Night	4 5% 2 5% 5% 3 4 4 5% 7% 56%	1440
	11th to 20th	Night	3 2 1 3 3 2 3 4 4 5% 71%	1440
	21st to end	Night	1 2 2 3 3 2 2 3 3 4 75%	1440
July	1st to 10th	Night	1 1 1 2 2 1 2 3 3 5% 81%	1440
	11th to 20th	Night	2 1 1 1 1 2 2 2 3 85%	1440
	21st to end	Night	2 1 1 2 3 2 3 2 3 4 79%	1630
August	1st to 10th	Night	2 2 2 2 1 3 3 5% 4 75%	1611
	11th to 20th	Night	2 2 1 2 2 1 2 2 3 4 78%	1717
	21st to end	Night	1 1 1 1 1 1 2 2 2 3 85%	1980
September	1st to 10th	Night	2 1 1 1 1 1 2 2 2 3 84%	1800
	11th to 20th	Night	3 2 1 2 2 1 2 3 4 5% 75%	1800
	21st to end	Night	3 2 1 2 2 1 2 3 4 6% 74%	2006
October	1st to 10th	Night	5% 4 2 3 3 2 3 3 3 5% 69%	2160
	11th to 20th	Night	3 2 1 3 3 1 3 3 4 7% 68%	2160
	21st to end	Night	5% 4 1 4 3 2 3 4 5% 6% 64%	2407
November	1st to 10th	Night	6% 6% 3 5% 5% 2 4 6% 6% 8% 48%	2405
	11th to 20th	Night	4 6% 2 5% 4 3 5% 5% 8% 8% 50%	2470
	21st to end	Night	2 4 3 5% 6% 3 5% 5% 6% 9% 52%	2655
December	1st to 10th	Night	5% 8% 4 7% 5% 3 4 5% 5% 9% 45%	2660
	11th to 20th	Night	8% 15% 5% 8% 6% 4 6% 5% 6% 9% 28%	3276
	21st to end	Night	6% 13% 4 9% 7% 4 5% 6% 7% 9% 31%	4862

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	46% 10% 15% 23% 5% 1	2539
	11th to 20th	Day	50% 9% 16% 14% 9% 2	2586
	21st to end	Day	52% 8% 12% 18% 8% 1	3146
February	1st to 10th	Day	37% 7% 14% 26% 12% 4	1710
	11th to 20th	Day	36% 6% 16% 24% 16% 2	1775
	21st to end	Day	39% 7% 14% 24% 13% 3	1570
March	1st to 10th	Day	47% 8% 10% 21% 11% 2	1914
	11th to 20th	Day	38% 5% 14% 21% 19% 2	2090
	21st to end	Day	43% 5% 18% 21% 10% 3	2411
April	1st to 10th	Day	40% 5% 14% 22% 16% 3	2185
	11th to 20th	Day	33% 6% 13% 25% 19% 4	2132
	21st to end	Day	32% 5% 14% 27% 19% 3	2160
May	1st to 10th	Day	25% 5% 10% 29% 27% 4	2338
	11th to 20th	Day	31% 4 10% 26% 23% 6%	2480
	21st to end	Day	37% 6% 11% 25% 17% 3	2724
June	1st to 10th	Day	28% 5% 10% 23% 27% 6%	2520
	11th to 20th	Day	18% 3 9% 21% 34% 14%	2520
	21st to end	Day	14% 2 3 16% 35% 29%	2520
July	1st to 10th	Day	11% 3 4 11% 26% 45%	2451
	11th to 20th	Day	9% 2 3 12% 24% 51%	2445
	21st to end	Day	13% 3 2 11% 19% 51%	2534
August	1st to 10th	Day	14% 3 4 14% 25% 40%	2312
	11th to 20th	Day	8% 2 3 13% 31% 43%	2183
	21st to end	Day	7% 2 2 12% 34% 43%	2376
September	1st to 10th	Day	9% 2 2 11% 29% 48%	2160
	11th to 20th	Day	15% 3 7% 18% 32% 25%	2160
	21st to end	Day	15% 2 6% 23% 32% 22%	1949
October	1st to 10th	Day	23% 3 7% 21% 31% 16%	1800
	11th to 20th	Day	20% 4 8% 23% 32% 14%	1800
	21st to end	Day	22% 4 12% 26% 23% 13%	1949
November	1st to 10th	Day	34% 5% 12% 21% 22% 6%	1674
	11th to 20th	Day	31% 7% 16% 25% 19% 1	1710
	21st to end	Day	33% 6% 14% 23% 21% 3	1521
December	1st to 10th	Day	40% 7% 13% 22% 17% 2	1520
	11th to 20th	Day	53% 8% 11% 19% 8% 1	1928
	21st to end	Day	41% 11% 20% 18% 8% 1	2794
January	1st to 10th	Night	39% 9% 22% 23% 7%	4406
	11th to 20th	Night	47% 10% 16% 14% 9% 4	4358
	21st to end	Night	53% 5% 13% 18% 10% 1	4521
February	1st to 10th	Night	34% 5% 15% 25% 16% 4	2470
	11th to 20th	Night	33% 6% 15% 27% 17% 1	2302
	21st to end	Night	35% 8% 16% 24% 14% 4	1884
March	1st to 10th	Night	41% 8% 17% 20% 11% 2	2261
	11th to 20th	Night	34% 7% 14% 24% 19% 2	2090
	21st to end	Night	38% 8% 20% 22% 11% 2	2185
April	1st to 10th	Night	33% 8% 16% 25% 13% 4	1820
	11th to 20th	Night	30% 7% 17% 24% 18% 4	1779
	21st to end	Night	24% 7% 18% 30% 19% 3	1800
May	1st to 10th	Night	24% 6% 11% 29% 27% 4	1617
	11th to 20th	Night	30% 6% 12% 30% 16% 6%	1416
	21st to end	Night	30% 7% 17% 26% 18% 3	1552
June	1st to 10th	Night	27% 7% 14% 26% 23% 5%	1440
	11th to 20th	Night	17% 4 9% 23% 37% 10%	1440
	21st to end	Night	14% 3 5% 18% 33% 27%	1440
July	1st to 10th	Night	9% 2 4 14% 31% 40%	1400
	11th to 20th	Night	8% 2 2 14% 25% 49%	1392
	21st to end	Night	11% 3 2 9% 26% 49%	1539
August	1st to 10th	Night	11% 4 4 17% 29% 35%	1602
	11th to 20th	Night	11% 3 2 13% 33% 38%	1717
	21st to end	Night	8% 2 2 13% 33% 41%	1980
September	1st to 10th	Night	9% 2 2 10% 28% 49%	1800
	11th to 20th	Night	13% 3 7% 21% 30% 27%	1800
	21st to end	Night	13% 2 6% 23% 33% 23%	2006
October	1st to 10th	Night	20% 3 8% 20% 29% 20%	2160
	11th to 20th	Night	16% 3 9% 25% 30% 17%	2160
	21st to end	Night	20% 4 13% 25% 25% 12%	2407
November	1st to 10th	Night	31% 7% 15% 22% 19% 7%	2405
	11th to 20th	Night	27% 8% 17% 24% 21% 2	2470
	21st to end	Night	27% 6% 17% 26% 20% 5%	2655
December	1st to 10th	Night	35% 8% 13% 22% 20% 3	2660
	11th to 20th	Night	50% 7% 10% 19% 13% 1	3276
	21st to end	Night	46% 8% 16% 19% 11% 1	4862

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	17% 21% 33% 21% 7% 1	180
	11th to 20th	Day	17% 15% 26% 26% 13% 2	213
	21st to end	Day	13% 14% 29% 28% 14% 3	407
February	1st to 10th	Day	13% 18% 25% 27% 14% 1	370
	11th to 20th	Day	13% 22% 27% 26% 12%	414
	21st to end	Day	12% 19% 25% 33% 10% 1	382
March	1st to 10th	Day	18% 23% 30% 20% 8% 1	460
	11th to 20th	Day	14% 20% 26% 24% 14% 2	460
	21st to end	Day	16% 23% 28% 23% 9% 1	506
April	1st to 10th	Day	15% 20% 27% 24% 11% 2	429
	11th to 20th	Day	18% 22% 25% 21% 12% 3	412
	21st to end	Day	13% 22% 25% 22% 15% 4	420
May	1st to 10th	Day	12% 16% 32% 25% 12% 4	423
	11th to 20th	Day	17% 19% 23% 21% 14% 6%	448
	21st to end	Day	12% 16% 18% 27% 21% 6%	485
June	1st to 10th	Day	9% 16% 22% 25% 19% 9%	450
	11th to 20th	Day	11% 13% 29% 26% 17% 4	450
	21st to end	Day	3 9% 20% 31% 26% 10%	450
July	1st to 10th	Day	3 5% 22% 39% 22% 9%	446
	11th to 20th	Day	1 4 22% 37% 23% 13%	444
	21st to end	Day	2 4 20% 37% 26% 12%	487
August	1st to 10th	Day	3 5% 21% 31% 27% 12%	447
	11th to 20th	Day	2 4 19% 32% 25% 17%	437
	21st to end	Day	2 5% 25% 33% 27% 9%	495
September	1st to 10th	Day	4 3 26% 32% 28% 8%	450
	11th to 20th	Day	5% 9% 22% 30% 25% 8%	450
	21st to end	Day	5% 11% 23% 33% 24% 3	450
October	1st to 10th	Day	8% 11% 25% 28% 21% 6%	450
	11th to 20th	Day	9% 14% 18% 32% 23% 3	450
	21st to end	Day	10% 15% 23% 30% 18% 3	464
November	1st to 10th	Day	16% 11% 19% 26% 24% 3	270
	11th to 20th	Day	7% 11% 26% 29% 21% 6%	270
	21st to end	Day	10% 13% 26% 28% 18% 4	180
December	1st to 10th	Day	13% 17% 27% 21% 17% 5%	180
	11th to 20th	Day	12% 14% 28% 27% 14% 5%	180
	21st to end	Day	10% 20% 26% 25% 18% 1	198
January	1st to 10th	Night	12% 10% 22% 34% 16% 5%	760
	11th to 20th	Night	8% 10% 22% 38% 18% 4	760
	21st to end	Night	11% 6% 23% 37% 20% 4	836
February	1st to 10th	Night	11% 9% 21% 39% 18% 2	760
	11th to 20th	Night	9% 11% 21% 38% 18% 3	744
	21st to end	Night	8% 14% 20% 39% 16% 2	628
March	1st to 10th	Night	14% 13% 24% 32% 16% 3	760
	11th to 20th	Night	12% 11% 20% 32% 23% 3	760
	21st to end	Night	11% 15% 25% 33% 15% 1	836
April	1st to 10th	Night	9% 12% 24% 38% 16% 2	728
	11th to 20th	Night	13% 13% 21% 32% 19% 3	711
	21st to end	Night	8% 11% 22% 34% 23% 3	720
May	1st to 10th	Night	7% 8% 27% 35% 20% 3	537
	11th to 20th	Night	6% 7% 20% 38% 25% 4	354
	21st to end	Night	10% 7% 19% 32% 29% 3	389
June	1st to 10th	Night	6% 6% 17% 40% 28% 3	360
	11th to 20th	Night	5% 5% 21% 41% 26% 2	360
	21st to end	Night	2 2 13% 48% 34% 2	360
July	1st to 10th	Night	1 1 7% 51% 38% 1	350
	11th to 20th	Night	2 1 9% 57% 30% 2	348
	21st to end	Night	2 1 4 48% 41% 4	448
August	1st to 10th	Night	3 4 45% 43% 5%	537
	11th to 20th	Night	2 1 9% 44% 38% 5%	649
	21st to end	Night	2 1 10% 45% 38% 4	792
September	1st to 10th	Night	3 1 13% 42% 37% 5%	720
	11th to 20th	Night	4 3 13% 35% 38% 7%	720
	21st to end	Night	4 4 15% 34% 35% 8%	720
October	1st to 10th	Night	7% 4 17% 39% 27% 7%	720
	11th to 20th	Night	5% 7% 13% 36% 34% 4	720
	21st to end	Night	7% 7% 17% 35% 25% 9%	792
November	1st to 10th	Night	9% 10% 16% 35% 25% 5%	740
	11th to 20th	Night	8% 8% 22% 39% 21% 3	760
	21st to end	Night	5% 9% 22% 36% 24% 4	760
December	1st to 10th	Night	11% 9% 21% 37% 19% 3	760
	11th to 20th	Night	15% 9% 20% 34% 19% 3	760
	21st to end	Night	13% 14% 23% 36% 13% 1	836

Page generated at 2024-03-31 03:08:53. Version ac07

Copyright © 2024 Attilla Danko.