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 2005-11-05 to 2017-09-19.

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 TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(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

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
48%
14789
14%
46903
14%
14758
49%
14758
19%
33177

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
34%
718
10%
2506
10%
716
36%
716
11%
1951
January16th to endNight
39%
768
13%
2544
13%
768
42%
768
15%
1855
February1st to 15thNight
35%
698
8%
2288
9%
697
35%
697
10%
1857
February16th to endNight
32%
632
10%
1990
7%
632
35%
632
12%
1571
March1st to 15thNight
34%
720
6%
2031
6%
720
35%
720
11%
1665
March16th to endNight
30%
768
6%
2086
4%
768
30%
768
10%
1775
April1st to 15thNight
31%
719
6%
1799
4%
719
31%
719
11%
1531
April16th to endNight
44%
630
8%
1710
6%
630
44%
630
15%
1359
May1st to 15thNight
48%
419
11%
1500
12%
419
49%
419
17%
1021
May16th to endNight
44%
375
8%
1496
11%
374
45%
374
11%
1101
June1st to 15thNight
51%
360
8%
1440
14%
360
51%
360
14%
1010
June16th to endNight
63%
360
14%
1440
23%
360
63%
360
25%
806
July1st to 15thNight
82%
340
21%
1360
36%
340
83%
340
47%
560
July16th to endNight
84%
406
31%
1444
41%
382
87%
382
58%
556
August1st to 15thNight
85%
538
29%
1611
27%
535
86%
535
55%
746
August16th to endNight
80%
675
35%
1821
25%
675
80%
675
58%
908
September1st to 15thNight
78%
720
32%
1800
21%
720
79%
720
59%
947
September16th to endNight
64%
671
26%
1849
23%
671
65%
671
33%
1147
October1st to 15thNight
58%
660
16%
1980
17%
660
60%
660
27%
1281
October16th to endNight
46%
704
13%
2115
15%
704
47%
704
18%
1551
November1st to 15thNight
32%
700
8%
2365
9%
700
33%
700
9%
1920
November16th to endNight
39%
720
8%
2520
9%
720
40%
720
12%
1944
December1st to 15thNight
37%
720
10%
2520
10%
720
40%
720
13%
1901
December16th to endNight
28%
768
8%
2688
9%
768
30%
768
9%
2214

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 ForecastData
Points
Cloud CoverDay
22%8%24423335%37%
47931
Night
23%9%24423335%36%
47073
Cloud CoverDay
22%8%25%423335%38%
47931
Night
23%9%25%423335%36%
47077
TransparencyDay
49%410%17%13%3
47605
Night
51%5%10%16%11%4
46903
SeeingDay
26%11%26%24%8%2
5713
Night
27%5%12%26%24%3
14798

By Month

Percentage Cloud Cover NW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
31%13%35%43333324%
1432
16th to endDay
29%10%34422335%31%
1677
February1st to 15thDay
29%12%35%5%35%5%45%18%
1576
16th to endDay
26%16%5%7%6%3333418%
1484
March1st to 15thDay
31%13%47%5%34335%15%
1929
16th to endDay
35%14%35%5%2434416%
2136
April1st to 15thDay
30%16%47%5%23335%16%
2149
16th to endDay
29%10%26%424336%25%
2248
May1st to 15thDay
25%7%25%423336%34%
2451
16th to endDay
33%8%34423346%25%
2615
June1st to 15thDay
27%7%36%423345%30%
2520
16th to endDay
17%5%24324347%44%
2520
July1st to 15thDay
6%31221223469%
2520
16th to endDay
6%31221222470%
2624
August1st to 15thDay
422223346%67%
2340
16th to endDay
6%212213245%69%
2381
September1st to 15thDay
7%32211135%69%
2160
16th to endDay
16%5%24323346%45%
1853
October1st to 15thDay
21%7%35%5%2333439%
1650
16th to endDay
28%6%15%423445%32%
1757
November1st to 15thDay
37%8%36%424345%20%
1493
16th to endDay
30%8%36%6%34335%23%
1440
December1st to 15thDay
28%11%36%5%3344424%
1440
16th to endDay
36%14%2432333419%
1536
January1st to 15thNight
31%12%36%5%2233424%
2506
16th to endNight
27%10%345%2333431%
2544
February1st to 15thNight
27%14%27%6%34435%20%
2276
16th to endNight
25%17%35%424335%23%
1990
March1st to 15thNight
29%14%36%5%33345%20%
2031
16th to endNight
32%14%35%5%34345%17%
2082
April1st to 15thNight
32%13%35%5%3433420%
1799
16th to endNight
26%10%34414447%27%
1710
May1st to 15thNight
20%11%24424345%35%
1499
16th to endNight
26%9%37%424346%27%
1496
June1st to 15thNight
23%7%25%5%23346%33%
1440
16th to endNight
16%5%12323336%51%
1440
July1st to 15thNight
6%11211223371%
1440
16th to endNight
5%1111212476%
1542
August1st to 15thNight
411321225%5%69%
1620
16th to endNight
4212212235%72%
1821
September1st to 15thNight
6%2221222373%
1800
16th to endNight
14%424422446%49%
1849
October1st to 15thNight
16%6%24423345%46%
1980
16th to endNight
25%8%35%5%2433433%
2115
November1st to 15thNight
34%8%36%5%34445%20%
2365
16th to endNight
31%8%25%5%3344426%
2520
December1st to 15thNight
29%11%45%42333427%
2520
16th to endNight
35%13%35%42433319%
2688

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
31%12%35%42433324%
1432
16th to endDay
28%11%25%312235%32%
1677
February1st to 15thDay
29%11%37%5%25%5%45%19%
1576
16th to endDay
27%16%37%6%3333419%
1484
March1st to 15thDay
31%14%36%5%24435%16%
1929
16th to endDay
34%13%46%434335%16%
2136
April1st to 15thDay
30%15%36%5%24235%17%
2149
16th to endDay
28%11%36%42435%5%25%
2248
May1st to 15thDay
24%7%35%423335%34%
2451
16th to endDay
32%8%25%5%23346%25%
2615
June1st to 15thDay
27%7%36%5%24335%30%
2520
16th to endDay
16%5%24423347%45%
2520
July1st to 15thDay
5%21221323469%
2520
16th to endDay
5%21311212472%
2624
August1st to 15thDay
3212212336%68%
2340
16th to endDay
5%212212335%69%
2381
September1st to 15thDay
6%311212225%69%
2160
16th to endDay
15%6%15%41345%5%46%
1853
October1st to 15thDay
21%7%245%3343439%
1650
16th to endDay
27%6%24433345%33%
1757
November1st to 15thDay
37%7%26%5%23335%20%
1493
16th to endDay
30%8%36%6%3434423%
1440
December1st to 15thDay
28%10%27%43443425%
1440
16th to endDay
35%15%2442343419%
1536
January1st to 15thNight
30%12%36%42333424%
2506
16th to endNight
27%9%25%42323431%
2544
February1st to 15thNight
27%14%37%5%34335%21%
2276
16th to endNight
24%17%46%33434424%
1990
March1st to 15thNight
29%14%35%5%33445%20%
2031
16th to endNight
32%15%36%433445%16%
2086
April1st to 15thNight
32%14%36%5%2433419%
1799
16th to endNight
27%9%35%315%435%28%
1710
May1st to 15thNight
21%9%34433345%35%
1499
16th to endNight
27%8%46%6%22337%27%
1496
June1st to 15thNight
24%6%25%423347%32%
1440
16th to endNight
17%5%23322335%51%
1440
July1st to 15thNight
5%11211224471%
1440
16th to endNight
421111132476%
1542
August1st to 15thNight
422212246%70%
1620
16th to endNight
43212123473%
1821
September1st to 15thNight
6%11221222373%
1800
16th to endNight
13%424433336%50%
1849
October1st to 15thNight
16%5%25%413435%46%
1980
16th to endNight
23%9%36%423445%33%
2115
November1st to 15thNight
35%8%26%6%24445%19%
2365
16th to endNight
31%8%25%43343426%
2520
December1st to 15thNight
28%11%36%42334427%
2520
16th to endNight
35%13%35%42432319%
2688

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
66%47%9%9%3
1432
16th to endDay
57%29%14%9%6%
1677
February1st to 15thDay
66%7%10%8%6%
1576
16th to endDay
69%5%8%8%6%1
1484
March1st to 15thDay
71%5%7%9%4
1929
16th to endDay
72%5%9%8%3
2136
April1st to 15thDay
71%5%11%8%3
2149
16th to endDay
61%5%13%11%5%1
2248
May1st to 15thDay
52%415%18%8%
2451
16th to endDay
61%5%13%16%2
2619
June1st to 15thDay
56%5%13%18%4
2520
16th to endDay
39%417%25%9%2
2520
July1st to 15thDay
19%313%25%29%7%
2371
16th to endDay
17%25%24%37%11%
2459
August1st to 15thDay
18%413%32%24%7%
2324
16th to endDay
18%310%31%30%5%
2381
September1st to 15thDay
20%28%26%28%14%
2160
16th to endDay
38%5%11%22%16%5%
1853
October1st to 15thDay
48%5%9%14%15%5%
1650
16th to endDay
52%6%11%15%12%2
1757
November1st to 15thDay
66%49%11%6%
1493
16th to endDay
63%5%6%10%7%5%
1440
December1st to 15thDay
61%5%7%14%9%
1440
16th to endDay
69%48%10%5%2
1536
January1st to 15thNight
64%47%11%9%2
2506
16th to endNight
57%39%10%10%8%
2544
February1st to 15thNight
67%5%9%11%5%1
2288
16th to endNight
64%410%11%6%2
1990
March1st to 15thNight
65%6%8%13%4
2031
16th to endNight
70%6%11%8%3
2086
April1st to 15thNight
69%5%10%8%5%
1799
16th to endNight
59%7%14%12%41
1710
May1st to 15thNight
51%415%16%10%1
1500
16th to endNight
59%5%14%16%3
1496
June1st to 15thNight
52%7%12%20%6%
1440
16th to endNight
36%5%17%28%8%3
1440
July1st to 15thNight
17%312%27%28%9%
1360
16th to endNight
13%26%24%38%14%
1444
August1st to 15thNight
17%310%34%26%7%
1611
16th to endNight
16%310%29%30%8%
1821
September1st to 15thNight
18%38%26%28%15%
1800
16th to endNight
35%5%10%23%15%9%
1849
October1st to 15thNight
40%6%13%16%17%6%
1980
16th to endNight
54%5%11%12%12%4
2115
November1st to 15thNight
66%6%8%10%7%1
2365
16th to endNight
60%6%8%9%8%6%
2520
December1st to 15thNight
60%5%8%14%10%
2520
16th to endNight
70%48%10%5%1
2688

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
41%8%20%18%11%
60
16th to endDay
37%7%20%17%16%1
205
February1st to 15thDay
37%10%22%22%6%
236
16th to endDay
38%17%22%18%2
222
March1st to 15thDay
48%17%19%11%2
270
16th to endDay
46%15%22%12%3
288
April1st to 15thDay
39%17%17%17%5%2
269
16th to endDay
41%16%21%15%22
270
May1st to 15thDay
35%13%27%17%42
288
16th to endDay
32%10%20%23%8%4
330
June1st to 15thDay
29%11%27%23%6%2
315
16th to endDay
12%12%34%29%7%3
315
July1st to 15thDay
8%8%36%32%10%4
305
16th to endDay
48%39%30%11%5%
327
August1st to 15thDay
36%32%40%9%6%
315
16th to endDay
6%10%27%34%13%7%
332
September1st to 15thDay
9%8%29%34%13%3
315
16th to endDay
21%9%30%26%11%
268
October1st to 15thDay
28%11%27%23%9%
255
16th to endDay
34%9%20%26%8%
269
November1st to 15thDay
37%5%14%34%5%2
75
16th to endDay
30%21%25%15%8%
60
December1st to 15thDay
56%16%16%10%
60
16th to endDay
45%6%14%20%12%1
64
January1st to 15thNight
36%7%15%22%15%2
720
16th to endNight
31%5%15%23%19%3
768
February1st to 15thNight
35%5%13%29%14%
704
16th to endNight
34%9%16%25%12%
632
March1st to 15thNight
38%8%13%24%13%1
720
16th to endNight
39%7%14%21%15%
768
April1st to 15thNight
37%8%14%22%16%1
719
16th to endNight
32%5%13%22%22%4
630
May1st to 15thNight
26%413%26%26%2
420
16th to endNight
30%39%25%28%2
375
June1st to 15thNight
25%311%30%28%1
360
16th to endNight
19%19%32%37%
360
July1st to 15thNight
6%16%33%50%1
340
16th to endNight
5%16%36%46%3
406
August1st to 15thNight
5%327%50%11%
538
16th to endNight
5%19%32%42%8%
675
September1st to 15thNight
6%19%27%45%8%
720
16th to endNight
15%39%32%33%5%
671
October1st to 15thNight
18%312%34%26%4
660
16th to endNight
28%5%11%26%21%5%
704
November1st to 15thNight
36%6%18%26%11%1
700
16th to endNight
36%8%12%26%15%1
720
December1st to 15thNight
36%415%26%15%1
720
16th to endNight
44%7%13%22%10%1
768
Page generated at 2017-09-20 01:49:57. Version ac04

Copyright 2017 A. Danko


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