Goudie Road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goudie Road clear sky chart from 2005-11-05 to 2017-12-02.

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
41%
15121
9%
47491
8%
15091
43%
15091
15%
35159

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
27%
726
5%
2512
5%
722
27%
722
7%
2125
January16th to endNight
34%
768
6%
2688
6%
768
36%
768
9%
2137
February1st to 15thNight
34%
701
6%
2397
6%
699
36%
699
10%
1901
February16th to endNight
39%
632
10%
1954
10%
632
42%
632
14%
1492
March1st to 15thNight
27%
720
5%
2160
3%
720
29%
720
10%
1766
March16th to endNight
33%
768
8%
2007
4%
768
35%
768
14%
1605
April1st to 15thNight
41%
719
7%
1799
3%
719
43%
719
16%
1418
April16th to endNight
40%
503
10%
1583
9%
503
43%
503
15%
1182
May1st to 15thNight
48%
359
10%
1440
15%
359
51%
359
16%
954
May16th to endNight
53%
374
7%
1451
10%
374
54%
374
15%
1020
June1st to 15thNight
45%
360
3%
1213
0%
360
45%
360
17%
862
June16th to endNight
51%
360
5%
1080
0%
360
51%
360
22%
751
July1st to 15thNight
65%
340
7%
1189
3%
340
66%
340
33%
637
July16th to endNight
68%
376
14%
1416
20%
354
73%
354
38%
657
August1st to 15thNight
78%
360
21%
1432
31%
358
80%
358
36%
673
August16th to endNight
67%
623
23%
1769
19%
623
69%
623
41%
994
September1st to 15thNight
65%
720
21%
1800
12%
720
66%
720
41%
1096
September16th to endNight
56%
716
19%
1944
15%
716
58%
716
27%
1315
October1st to 15thNight
48%
720
12%
2154
11%
720
50%
720
21%
1498
October16th to endNight
39%
768
10%
2484
9%
768
43%
768
14%
1823
November1st to 15thNight
27%
760
8%
2581
7%
760
29%
760
9%
2110
November16th to endNight
27%
878
5%
2828
2%
878
29%
878
8%
2366
December1st to 15thNight
30%
910
5%
2730
4%
910
31%
910
9%
2277
December16th to endNight
22%
960
4%
2880
2%
960
24%
960
7%
2500

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
14%11%47%6%35%45%5%30%
48975
Night
12%12%47%6%3445%6%32%
47652
Cloud CoverDay
14%13%5%7%6%35%445%28%
48975
Night
12%14%5%7%5%3445%5%30%
47656
TransparencyDay
55%7%12%15%7%1
48640
Night
53%8%13%16%7%1
47491
SeeingDay
21%14%25%23%12%3
6320
Night
18%10%20%28%18%4
15126

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
18%14%6%10%7%35%5%45%18%
1432
16th to endDay
12%16%5%8%6%35%445%26%
1536
February1st to 15thDay
13%17%7%10%7%3445%420%
1465
16th to endDay
10%17%8%10%7%35%35%5%20%
1520
March1st to 15thDay
15%18%6%10%6%4446%5%17%
1800
16th to endDay
13%18%7%10%7%35%5%5%5%16%
2217
April1st to 15thDay
12%18%6%10%7%46%5%5%416%
2149
16th to endDay
14%16%5%9%7%45%345%22%
2373
May1st to 15thDay
14%13%47%6%345%46%28%
2511
16th to endDay
20%9%38%7%46%46%6%22%
2657
June1st to 15thDay
24%8%48%6%45%435%23%
2743
16th to endDay
19%7%46%7%45%45%5%28%
2880
July1st to 15thDay
8%425%5%35%45%6%47%
2694
16th to endDay
7%324424446%55%
2657
August1st to 15thDay
7%4145%245%6%8%50%
2520
16th to endDay
9%5%25%43446%6%47%
2431
September1st to 15thDay
10%5%24324345%52%
2160
16th to endDay
17%6%245%3445%6%38%
2016
October1st to 15thDay
13%12%37%5%35%346%34%
1804
16th to endDay
21%12%37%434446%26%
1740
November1st to 15thDay
20%19%5%8%7%3445%5%15%
1607
16th to endDay
13%17%6%9%6%35%5%5%5%20%
1449
December1st to 15thDay
9%16%6%10%7%37%5%5%6%20%
1267
16th to endDay
12%18%8%9%7%46%45%417%
1347
January1st to 15thNight
18%17%7%9%6%34345%18%
2512
16th to endNight
10%17%6%7%6%25%5%5%7%22%
2688
February1st to 15thNight
13%17%6%8%6%34346%24%
2385
16th to endNight
8%18%6%9%6%34345%28%
1954
March1st to 15thNight
11%18%5%9%8%44446%22%
2160
16th to endNight
11%14%5%7%7%36%5%5%5%25%
2003
April1st to 15thNight
10%12%47%8%36%5%5%6%28%
1799
16th to endNight
9%13%5%7%8%44446%31%
1583
May1st to 15thNight
9%10%37%6%35%45%5%38%
1439
16th to endNight
14%9%35%435%6%7%7%30%
1451
June1st to 15thNight
17%6%36%5%35%47%7%32%
1213
16th to endNight
13%5%35%5%45%36%6%38%
1080
July1st to 15thNight
5%42442346%7%55%
1263
16th to endNight
4212313448%62%
1512
August1st to 15thNight
6%22324345%62%
1440
16th to endNight
5%313325%35%8%55%
1769
September1st to 15thNight
6%5%1343443457%
1800
16th to endNight
12%6%25%43445%7%43%
1944
October1st to 15thNight
12%9%25%5%35%435%40%
2154
16th to endNight
17%11%37%5%2446%5%30%
2484
November1st to 15thNight
19%17%47%5%35%445%21%
2581
16th to endNight
14%18%6%9%6%24446%21%
2828
December1st to 15thNight
11%16%7%9%7%45%5%45%21%
2730
16th to endNight
12%19%8%11%7%345%5%417%
2880

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
16%16%6%11%8%345%45%16%
1432
16th to endDay
13%18%7%7%5%2446%5%24%
1536
February1st to 15thDay
13%20%7%9%6%2445%418%
1465
16th to endDay
9%21%10%10%6%35%5%4319%
1520
March1st to 15thDay
16%22%8%9%6%35%45%416%
1800
16th to endDay
14%22%8%10%6%35%445%15%
2217
April1st to 15thDay
12%21%8%10%7%46%44414%
2149
16th to endDay
13%20%6%8%7%4444421%
2373
May1st to 15thDay
14%16%46%6%3445%6%27%
2511
16th to endDay
21%11%37%7%45%5%5%5%20%
2657
June1st to 15thDay
26%10%48%7%35%33422%
2743
16th to endDay
21%10%45%7%36%5%45%27%
2880
July1st to 15thDay
10%5%25%5%35%45%6%45%
2694
16th to endDay
7%424434446%53%
2657
August1st to 15thDay
8%424425%5%6%8%48%
2520
16th to endDay
10%6%25%4345%5%6%45%
2431
September1st to 15thDay
11%6%25%324435%51%
2160
16th to endDay
18%8%2443445%6%36%
2016
October1st to 15thDay
14%13%47%5%35%445%32%
1804
16th to endDay
21%16%36%433345%25%
1740
November1st to 15thDay
19%21%6%8%7%3444414%
1607
16th to endDay
12%21%7%8%5%35%5%4419%
1449
December1st to 15thDay
10%17%7%10%6%47%45%5%19%
1267
16th to endDay
13%19%9%12%6%45%44316%
1347
January1st to 15thNight
17%20%6%10%6%3434417%
2512
16th to endNight
11%18%7%8%6%35%5%5%7%20%
2688
February1st to 15thNight
13%20%6%7%5%3444423%
2385
16th to endNight
9%18%7%9%7%25%45%5%25%
1954
March1st to 15thNight
11%20%7%10%6%45%446%19%
2160
16th to endNight
13%15%6%7%6%36%5%5%5%24%
2007
April1st to 15thNight
10%13%5%9%7%4445%6%26%
1799
16th to endNight
9%15%5%8%6%34445%30%
1583
May1st to 15thNight
9%12%47%6%35%44437%
1439
16th to endNight
15%10%46%435%5%6%8%28%
1451
June1st to 15thNight
18%8%45%5%35%46%6%31%
1213
16th to endNight
14%8%25%5%26%45%6%38%
1080
July1st to 15thNight
6%5%1442437%8%53%
1263
16th to endNight
43331345%6%62%
1512
August1st to 15thNight
5%2343335%5%61%
1440
16th to endNight
6%41443335%8%55%
1769
September1st to 15thNight
7%5%24424445%56%
1800
16th to endNight
13%8%25%42435%7%41%
1944
October1st to 15thNight
13%9%35%6%35%445%38%
2154
16th to endNight
17%12%47%4245%5%5%29%
2484
November1st to 15thNight
19%18%48%6%2444419%
2581
16th to endNight
14%20%8%8%6%33445%19%
2828
December1st to 15thNight
11%19%7%10%7%45%44420%
2730
16th to endNight
11%21%8%12%7%3444416%
2880

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
68%10%10%7%3
1432
16th to endDay
59%8%14%13%21
1536
February1st to 15thDay
66%10%10%9%2
1465
16th to endDay
66%7%10%10%4
1520
March1st to 15thDay
69%8%11%8%1
1800
16th to endDay
71%6%11%8%2
2217
April1st to 15thDay
70%8%9%9%1
2149
16th to endDay
63%7%12%13%2
2373
May1st to 15thDay
55%7%12%15%7%
2511
16th to endDay
62%8%13%13%1
2661
June1st to 15thDay
64%6%10%12%41
2743
16th to endDay
55%7%10%16%8%
2880
July1st to 15thDay
37%7%12%20%17%5%
2539
16th to endDay
30%7%13%25%21%3
2490
August1st to 15thDay
31%8%17%26%13%3
2503
16th to endDay
35%7%14%27%13%1
2431
September1st to 15thDay
34%5%13%26%18%1
2160
16th to endDay
45%8%15%20%8%2
2016
October1st to 15thDay
52%7%16%19%5%
1804
16th to endDay
59%7%14%15%3
1740
November1st to 15thDay
70%7%10%8%1
1607
16th to endDay
65%10%11%7%4
1449
December1st to 15thDay
63%11%9%12%2
1267
16th to endDay
71%8%11%6%1
1347
January1st to 15thNight
69%8%10%7%3
2512
16th to endNight
60%10%13%9%41
2688
February1st to 15thNight
62%8%12%12%41
2397
16th to endNight
58%6%14%14%6%
1954
March1st to 15thNight
64%8%14%10%2
2160
16th to endNight
58%8%15%13%3
2007
April1st to 15thNight
55%9%16%13%4
1799
16th to endNight
53%8%15%17%4
1583
May1st to 15thNight
45%9%15%16%12%
1440
16th to endNight
49%9%16%20%3
1451
June1st to 15thNight
49%8%13%19%8%
1213
16th to endNight
43%9%16%21%7%
1080
July1st to 15thNight
28%6%14%25%19%5%
1189
16th to endNight
20%7%16%28%23%3
1416
August1st to 15thNight
23%6%13%33%18%4
1432
16th to endNight
26%5%16%31%17%2
1769
September1st to 15thNight
29%5%12%28%20%3
1800
16th to endNight
40%8%13%24%11%2
1944
October1st to 15thNight
46%7%15%21%8%
2154
16th to endNight
53%8%14%19%4
2484
November1st to 15thNight
65%8%9%11%4
2581
16th to endNight
67%8%10%7%4
2828
December1st to 15thNight
66%9%11%11%1
2730
16th to endNight
70%9%10%7%1
2880

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
11%123%23%28%11%
60
16th to endDay
23%10%26%28%46%
64
February1st to 15thDay
28%18%20%20%8%4
125
16th to endDay
20%17%29%19%10%2
228
March1st to 15thDay
34%27%23%12%2
270
16th to endDay
30%22%27%15%3
288
April1st to 15thDay
26%19%28%17%7%1
269
16th to endDay
24%20%28%15%7%3
270
May1st to 15thDay
23%20%23%22%7%1
288
16th to endDay
24%8%19%22%17%6%
372
June1st to 15thDay
24%9%21%22%18%3
538
16th to endDay
22%9%24%24%15%3
675
July1st to 15thDay
10%10%25%33%16%2
473
16th to endDay
9%11%31%31%13%2
327
August1st to 15thDay
11%7%23%29%20%6%
315
16th to endDay
11%12%29%29%11%5%
332
September1st to 15thDay
19%11%26%21%15%4
315
16th to endDay
21%11%27%22%13%3
315
October1st to 15thDay
24%18%26%18%10%1
315
16th to endDay
30%10%20%25%12%1
156
November1st to 15thDay
29%21%24%13%9%1
109
16th to endDay
28%16%28%11%6%7%
90
December1st to 15thDay
20%17%17%24%14%4
62
16th to endDay
7%25%28%28%7%3
64
January1st to 15thNight
24%14%22%24%12%1
726
16th to endNight
16%11%25%29%14%2
768
February1st to 15thNight
22%11%19%28%14%3
704
16th to endNight
15%12%21%26%19%3
632
March1st to 15thNight
22%15%25%24%10%1
720
16th to endNight
18%15%25%25%12%3
768
April1st to 15thNight
16%10%18%32%17%4
719
16th to endNight
14%8%25%34%14%2
503
May1st to 15thNight
14%7%20%35%18%3
360
16th to endNight
20%414%26%27%6%
375
June1st to 15thNight
17%7%20%27%23%3
360
16th to endNight
16%416%40%18%3
360
July1st to 15thNight
6%317%27%39%4
340
16th to endNight
6%316%32%37%4
376
August1st to 15thNight
7%17%28%42%12%
360
16th to endNight
9%314%34%33%4
623
September1st to 15thNight
10%413%26%30%13%
720
16th to endNight
18%5%13%29%25%7%
716
October1st to 15thNight
18%6%19%28%23%4
720
16th to endNight
24%9%19%27%15%4
768
November1st to 15thNight
27%15%22%24%8%1
760
16th to endNight
25%14%23%21%10%4
878
December1st to 15thNight
19%12%24%30%11%1
910
16th to endNight
21%14%31%24%7%
960
Page generated at 2017-12-03 08:16:47. Version ac04

Copyright 2017 A. Danko


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