Eagle's Rest
Clear Sky Chart
History

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

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	17% 9% 2 6% 4 3 3 3 4 5% 43%	101513
	Night	21% 12% 3 6% 4 3 3 3 4 5% 38%	97655
Transparency	Day	44% 6% 11% 18% 15% 7%	101259
	Night	49% 6% 11% 16% 13% 5%	97498
Seeing	Day	22% 12% 26% 25% 11% 3	14779
	Night	25% 7% 14% 29% 22% 3	23753

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	29% 22% 4 9% 4 4 3 2 4 3 14%	2539
	11th to 20th	Day	36% 17% 3 6% 4 3 3 2 2 3 20%	2569
	21st to end	Day	32% 14% 3 8% 5% 4 3 3 5% 5% 20%	3146
February	1st to 10th	Day	26% 14% 3 9% 5% 4 4 5% 4 5% 21%	1710
	11th to 20th	Day	25% 16% 4 8% 4 4 4 3 4 5% 22%	1665
	21st to end	Day	26% 21% 3 7% 5% 5% 3 3 3 5% 19%	1513
March	1st to 10th	Day	17% 19% 5% 9% 5% 5% 4 3 4 6% 23%	3319
	11th to 20th	Day	18% 12% 3 6% 4 4 4 3 3 4 40%	3490
	21st to end	Day	25% 15% 4 10% 5% 6% 5% 4 4 5% 16%	3899
April	1st to 10th	Day	27% 18% 3 9% 6% 4 4 2 4 4 18%	2280
	11th to 20th	Day	24% 17% 4 7% 4 4 4 2 4 5% 25%	2249
	21st to end	Day	26% 11% 3 7% 4 4 4 3 5% 6% 27%	2419
May	1st to 10th	Day	22% 12% 3 7% 4 4 3 3 4 4 35%	4265
	11th to 20th	Day	14% 6% 2 5% 3 3 3 3 5% 7% 51%	4377
	21st to end	Day	20% 10% 3 7% 5% 4 4 3 5% 8% 32%	4813
June	1st to 10th	Day	24% 9% 3 6% 4 4 4 3 5% 5% 32%	2660
	11th to 20th	Day	19% 8% 3 5% 4 4 5% 4 5% 7% 36%	2660
	21st to end	Day	9% 5% 1 5% 3 3 3 2 4 6% 59%	2660
July	1st to 10th	Day	3 2 1 2 1 1 1 1 2 3 82%	4420
	11th to 20th	Day	3 2 1 3 2 2 2 2 3 3 77%	4420
	21st to end	Day	3 2 1 2 2 1 2 1 3 4 79%	4706
August	1st to 10th	Day	3 3 1 4 2 2 3 2 3 5% 72%	4091
	11th to 20th	Day	4 3 1 3 2 3 3 4 5% 7% 66%	4026
	21st to end	Day	6% 4 1 3 2 2 2 2 4 6% 67%	4252
September	1st to 10th	Day	6% 3 1 3 2 2 3 3 3 5% 69%	2280
	11th to 20th	Day	11% 6% 2 4 5% 3 4 3 4 6% 52%	2280
	21st to end	Day	13% 6% 1 6% 3 3 4 3 5% 6% 51%	1996
October	1st to 10th	Day	18% 8% 2 4 3 3 4 4 3 4 47%	1900
	11th to 20th	Day	20% 6% 2 6% 4 4 4 3 4 6% 40%	1900
	21st to end	Day	23% 8% 3 7% 4 4 4 3 5% 5% 35%	2085
November	1st to 10th	Day	31% 9% 3 8% 6% 4 4 3 4 5% 23%	1642
	11th to 20th	Day	29% 10% 2 9% 5% 4 4 3 5% 5% 24%	1520
	21st to end	Day	27% 10% 3 7% 5% 4 4 3 4 5% 27%	1520
December	1st to 10th	Day	23% 11% 3 7% 4 4 4 3 4 5% 32%	1520
	11th to 20th	Day	26% 14% 4 8% 5% 4 4 4 5% 6% 21%	1928
	21st to end	Day	29% 18% 4 8% 4 4 3 3 4 4 20%	2794
January	1st to 10th	Night	33% 21% 4 7% 4 4 3 3 4 4 13%	4406
	11th to 20th	Night	36% 16% 3 6% 3 3 3 2 3 4 21%	4389
	21st to end	Night	35% 15% 3 8% 3 4 3 2 3 4 20%	4521
February	1st to 10th	Night	24% 19% 3 8% 5% 4 4 3 4 5% 20%	2470
	11th to 20th	Night	24% 18% 4 7% 4 4 4 3 4 4 25%	2402
	21st to end	Night	24% 21% 4 6% 4 4 4 3 4 5% 22%	1941
March	1st to 10th	Night	18% 21% 5% 9% 5% 4 4 3 5% 5% 21%	3553
	11th to 20th	Night	16% 14% 3 7% 3 3 3 2 3 4 41%	3490
	21st to end	Night	24% 22% 4 9% 5% 5% 4 3 3 4 16%	3753
April	1st to 10th	Night	28% 18% 4 6% 5% 4 3 3 3 5% 22%	1900
	11th to 20th	Night	26% 14% 3 6% 3 4 4 4 4 4 27%	1879
	21st to end	Night	28% 13% 3 6% 3 4 5% 3 4 5% 27%	1758
May	1st to 10th	Night	25% 18% 4 6% 3 3 2 3 3 4 31%	2700
	11th to 20th	Night	14% 8% 2 6% 3 3 3 2 4 4 50%	2516
	21st to end	Night	24% 11% 2 5% 4 2 3 2 4 6% 36%	2762
June	1st to 10th	Night	24% 8% 2 7% 4 3 3 3 5% 6% 35%	1520
	11th to 20th	Night	20% 9% 3 6% 3 3 3 3 4 6% 40%	1520
	21st to end	Night	12% 4 1 3 3 2 3 2 3 4 62%	1520
July	1st to 10th	Night	4 2 1 1 1 2 1 1 3 3 81%	2540
	11th to 20th	Night	3 2 1 2 2 1 2 2 2 2 80%	2540
	21st to end	Night	5% 1 1 1 1 1 1 2 2 3 81%	2844
August	1st to 10th	Night	3 2 1 3 2 3 3 2 4 5% 73%	2848
	11th to 20th	Night	3 4 1 4 3 3 3 3 5% 6% 64%	2812
	21st to end	Night	7% 4 1 4 2 2 2 2 3 3 68%	3424
September	1st to 10th	Night	7% 3 1 4 2 1 2 2 3 4 72%	1900
	11th to 20th	Night	11% 5% 2 5% 4 4 4 2 4 6% 54%	1900
	21st to end	Night	13% 6% 2 4 3 3 3 3 3 6% 52%	2179
October	1st to 10th	Night	14% 8% 2 5% 3 2 3 3 3 5% 53%	2280
	11th to 20th	Night	18% 7% 2 6% 3 3 4 3 5% 6% 44%	2280
	21st to end	Night	22% 10% 3 8% 4 3 3 3 3 5% 36%	2512
November	1st to 10th	Night	29% 9% 3 7% 5% 4 4 3 5% 5% 25%	2478
	11th to 20th	Night	31% 9% 3 7% 5% 4 4 4 5% 5% 24%	2660
	21st to end	Night	25% 11% 2 7% 4 4 3 3 4 5% 31%	2660
December	1st to 10th	Night	25% 12% 3 7% 4 4 3 3 5% 6% 29%	2660
	11th to 20th	Night	28% 14% 4 8% 4 4 4 3 5% 6% 21%	3276
	21st to end	Night	26% 15% 4 8% 4 4 5% 3 4 4 22%	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	76% 4 8% 8% 3 1	2539
	11th to 20th	Day	71% 4 4 11% 5% 4	2569
	21st to end	Day	65% 7% 9% 10% 6% 2	3146
February	1st to 10th	Day	64% 7% 10% 11% 7% 1	1710
	11th to 20th	Day	64% 7% 11% 9% 7% 2	1674
	21st to end	Day	70% 4 8% 10% 6% 2	1513
March	1st to 10th	Day	61% 6% 8% 19% 6%	3319
	11th to 20th	Day	48% 7% 8% 22% 13% 2	3490
	21st to end	Day	67% 10% 11% 8% 4	3899
April	1st to 10th	Day	70% 6% 10% 10% 5%	2280
	11th to 20th	Day	63% 6% 12% 10% 7% 3	2252
	21st to end	Day	58% 6% 13% 15% 6% 1	2419
May	1st to 10th	Day	52% 7% 12% 19% 10%	4265
	11th to 20th	Day	33% 6% 15% 32% 14% 1	4380
	21st to end	Day	49% 9% 24% 16% 2	4814
June	1st to 10th	Day	51% 7% 15% 20% 6%	2660
	11th to 20th	Day	47% 7% 18% 21% 7% 1	2660
	21st to end	Day	28% 4 15% 34% 15% 4	2660
July	1st to 10th	Day	11% 3 8% 15% 26% 37%	4351
	11th to 20th	Day	14% 2 5% 16% 27% 36%	4345
	21st to end	Day	11% 2 7% 25% 43% 13%	4557
August	1st to 10th	Day	16% 3 8% 23% 36% 14%	4076
	11th to 20th	Day	18% 5% 12% 35% 25% 5%	4065
	21st to end	Day	20% 4 15% 25% 25% 12%	4251
September	1st to 10th	Day	20% 3 7% 28% 28% 15%	2280
	11th to 20th	Day	33% 5% 12% 23% 18% 9%	2280
	21st to end	Day	33% 6% 12% 23% 17% 9%	1996
October	1st to 10th	Day	40% 6% 9% 17% 17% 11%	1900
	11th to 20th	Day	45% 6% 12% 15% 17% 5%	1900
	21st to end	Day	51% 7% 9% 14% 15% 4	2085
November	1st to 10th	Day	65% 5% 8% 13% 8% 1	1642
	11th to 20th	Day	62% 5% 9% 10% 8% 5%	1520
	21st to end	Day	58% 6% 7% 11% 12% 6%	1520
December	1st to 10th	Day	53% 7% 9% 16% 12% 3	1520
	11th to 20th	Day	62% 7% 12% 10% 8% 1	1928
	21st to end	Day	69% 5% 8% 13% 3 2	2794
January	1st to 10th	Night	76% 6% 7% 7% 3 2	4406
	11th to 20th	Night	68% 4 8% 10% 6% 4	4389
	21st to end	Night	70% 4 7% 9% 7% 2	4521
February	1st to 10th	Night	66% 6% 9% 11% 6% 2	2470
	11th to 20th	Night	63% 6% 10% 12% 6% 3	2404
	21st to end	Night	65% 4 10% 11% 7% 2	1941
March	1st to 10th	Night	63% 7% 12% 15% 3 1	3553
	11th to 20th	Night	48% 7% 10% 22% 12% 1	3490
	21st to end	Night	70% 9% 11% 9% 2	3753
April	1st to 10th	Night	66% 6% 12% 10% 5%	1900
	11th to 20th	Night	60% 8% 12% 11% 5% 3	1879
	21st to end	Night	60% 8% 13% 12% 5% 2	1758
May	1st to 10th	Night	57% 6% 11% 14% 11% 1	2700
	11th to 20th	Night	37% 6% 13% 34% 10% 1	2516
	21st to end	Night	49% 9% 25% 15% 2	2762
June	1st to 10th	Night	50% 8% 13% 24% 4	1520
	11th to 20th	Night	46% 6% 17% 23% 7% 1	1520
	21st to end	Night	27% 5% 17% 33% 13% 5%	1520
July	1st to 10th	Night	11% 3 8% 17% 26% 35%	2500
	11th to 20th	Night	12% 2 5% 17% 35% 28%	2492
	21st to end	Night	11% 2 8% 25% 44% 10%	2755
August	1st to 10th	Night	15% 3 8% 27% 35% 12%	2839
	11th to 20th	Night	19% 5% 15% 35% 22% 4	2839
	21st to end	Night	22% 3 12% 25% 28% 9%	3424
September	1st to 10th	Night	18% 3 9% 28% 27% 15%	1900
	11th to 20th	Night	31% 6% 11% 25% 16% 10%	1900
	21st to end	Night	34% 5% 12% 23% 15% 12%	2179
October	1st to 10th	Night	36% 5% 11% 19% 18% 10%	2280
	11th to 20th	Night	42% 6% 14% 16% 17% 5%	2280
	21st to end	Night	52% 5% 9% 12% 14% 7%	2512
November	1st to 10th	Night	60% 7% 9% 12% 10% 2	2478
	11th to 20th	Night	61% 8% 8% 10% 8% 4	2660
	21st to end	Night	54% 7% 9% 11% 13% 7%	2660
December	1st to 10th	Night	56% 6% 9% 14% 13% 3	2660
	11th to 20th	Night	63% 7% 11% 9% 9% 1	3276
	21st to end	Night	62% 8% 11% 14% 4 2	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	43% 14% 20% 15% 7% 1	180
	11th to 20th	Day	40% 11% 16% 19% 11% 3	196
	21st to end	Day	33% 13% 22% 16% 13% 2	407
February	1st to 10th	Day	31% 15% 26% 18% 9% 2	370
	11th to 20th	Day	35% 17% 24% 17% 5% 1	365
	21st to end	Day	36% 20% 19% 21% 4 1	355
March	1st to 10th	Day	33% 20% 23% 17% 7%	460
	11th to 20th	Day	31% 13% 27% 18% 9% 2	460
	21st to end	Day	36% 17% 25% 17% 5% 1	506
April	1st to 10th	Day	35% 19% 18% 20% 7% 1	460
	11th to 20th	Day	35% 17% 22% 18% 5% 2	452
	21st to end	Day	33% 17% 22% 21% 6% 2	460
May	1st to 10th	Day	24% 15% 28% 22% 6% 3	463
	11th to 20th	Day	31% 11% 25% 21% 9% 3	488
	21st to end	Day	23% 14% 25% 26% 8% 4	529
June	1st to 10th	Day	23% 13% 25% 26% 9% 4	490
	11th to 20th	Day	21% 18% 30% 22% 8% 1	490
	21st to end	Day	6% 10% 35% 32% 11% 5%	490
July	1st to 10th	Day	7% 7% 36% 34% 11% 5%	486
	11th to 20th	Day	4 8% 38% 31% 13% 6%	484
	21st to end	Day	2 5% 36% 32% 16% 8%	531
August	1st to 10th	Day	3 6% 31% 39% 14% 7%	487
	11th to 20th	Day	4 7% 27% 36% 17% 9%	477
	21st to end	Day	8% 9% 33% 31% 14% 5%	539
September	1st to 10th	Day	7% 8% 31% 32% 16% 6%	490
	11th to 20th	Day	16% 7% 28% 33% 15% 2	490
	21st to end	Day	15% 12% 29% 27% 15% 2	490
October	1st to 10th	Day	19% 10% 27% 24% 16% 3	490
	11th to 20th	Day	21% 9% 21% 27% 18% 3	490
	21st to end	Day	27% 13% 22% 22% 12% 4	534
November	1st to 10th	Day	31% 16% 20% 19% 13% 2	252
	11th to 20th	Day	26% 14% 22% 21% 13% 5%	180
	21st to end	Day	30% 13% 17% 23% 16% 1	180
December	1st to 10th	Day	32% 12% 21% 20% 9% 6%	180
	11th to 20th	Day	38% 14% 18% 22% 6% 2	180
	21st to end	Day	38% 13% 18% 21% 8% 2	198
January	1st to 10th	Night	40% 9% 19% 18% 11% 2	760
	11th to 20th	Night	33% 10% 18% 21% 15% 3	760
	21st to end	Night	31% 7% 17% 28% 14% 2	836
February	1st to 10th	Night	34% 8% 16% 31% 10% 1	760
	11th to 20th	Night	31% 10% 17% 30% 12% 1	744
	21st to end	Night	36% 11% 17% 27% 10%	628
March	1st to 10th	Night	34% 11% 16% 27% 11% 1	760
	11th to 20th	Night	27% 10% 18% 30% 15% 1	760
	21st to end	Night	36% 11% 17% 22% 13% 1	836
April	1st to 10th	Night	36% 9% 16% 24% 15% 1	760
	11th to 20th	Night	31% 10% 16% 25% 16% 3	751
	21st to end	Night	32% 9% 14% 26% 17% 2	618
May	1st to 10th	Night	25% 7% 15% 29% 21% 3	475
	11th to 20th	Night	21% 5% 12% 31% 29% 2	374
	21st to end	Night	27% 4 15% 27% 26% 2	411
June	1st to 10th	Night	23% 6% 10% 31% 28% 2	380
	11th to 20th	Night	20% 8% 16% 32% 24% 1	380
	21st to end	Night	14% 2 9% 36% 40%	380
July	1st to 10th	Night	6% 3 6% 36% 47% 1	370
	11th to 20th	Night	5% 2 11% 44% 36% 1	368
	21st to end	Night	4 1 7% 38% 46% 4	463
August	1st to 10th	Night	5% 1 5% 33% 48% 9%	567
	11th to 20th	Night	4 1 6% 32% 48% 8%	564
	21st to end	Night	5% 3 12% 38% 37% 5%	788
September	1st to 10th	Night	7% 2 12% 33% 41% 4	760
	11th to 20th	Night	11% 4 11% 33% 34% 7%	760
	21st to end	Night	15% 4 12% 33% 30% 5%	760
October	1st to 10th	Night	17% 4 13% 36% 27% 4	760
	11th to 20th	Night	21% 5% 10% 34% 25% 4	760
	21st to end	Night	25% 9% 16% 29% 17% 5%	836
November	1st to 10th	Night	32% 7% 19% 27% 13% 2	748
	11th to 20th	Night	35% 8% 18% 26% 11% 2	760
	21st to end	Night	29% 8% 16% 31% 14% 1	760
December	1st to 10th	Night	30% 8% 18% 25% 16% 2	760
	11th to 20th	Night	39% 7% 16% 24% 11% 1	760
	21st to end	Night	43% 11% 16% 21% 8% 1	836

Page generated at 2024-10-31 00:39:21. Version ac07

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