Port Coquitlam
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Port Coquitlam clear sky chart from 2005-11-05 to

2017-09-12
.

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
32%
14453
8%
46667
6%
14425
35%
14425
12%
35597

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
25%
750
10%
2686
8%
746
29%
746
8%
2202
January16th to endNight
24%
778
8%
2741
7%
778
27%
778
8%
2191
February1st to 15thNight
22%
700
5%
2288
4%
700
24%
700
7%
1897
February16th to endNight
25%
632
12%
2038
7%
632
32%
632
11%
1568
March1st to 15thNight
18%
720
3%
2067
2%
720
19%
720
7%
1787
March16th to endNight
19%
768
5%
2070
2%
768
22%
768
7%
1792
April1st to 15thNight
27%
719
6%
1799
3%
719
28%
719
12%
1486
April16th to endNight
28%
503
6%
1583
4%
503
31%
503
9%
1260
May1st to 15thNight
41%
359
11%
1439
15%
359
45%
359
13%
972
May16th to endNight
44%
374
5%
1469
7%
374
45%
374
11%
1040
June1st to 15thNight
42%
360
2%
1260
1%
360
43%
360
13%
919
June16th to endNight
41%
360
4%
1260
1%
360
42%
360
13%
908
July1st to 15thNight
65%
340
9%
1190
8%
340
66%
340
29%
664
July16th to endNight
65%
376
14%
1335
18%
354
73%
354
32%
674
August1st to 15thNight
69%
423
15%
1495
21%
421
70%
421
34%
743
August16th to endNight
62%
615
17%
1761
14%
615
64%
615
31%
1060
September1st to 15thNight
62%
706
19%
1765
11%
706
64%
706
38%
1075
September16th to endNight
39%
656
15%
1810
11%
656
42%
656
18%
1323
October1st to 15thNight
35%
660
10%
1980
9%
660
37%
660
16%
1434
October16th to endNight
27%
704
5%
2201
4%
704
29%
704
8%
1808
November1st to 15thNight
14%
700
5%
2450
3%
700
17%
700
5%
2132
November16th to endNight
18%
720
5%
2520
3%
720
21%
720
6%
2068
December1st to 15thNight
19%
730
8%
2580
4%
730
24%
730
7%
2126
December16th to endNight
13%
800
6%
2880
2%
800
17%
800
5%
2468

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
30%9%35%42333427%
48025
Night
31%8%35%423345%28%
46821
Cloud CoverDay
32%9%35%42333427%
48025
Night
33%8%2442333428%
46824
TransparencyDay
60%6%11%14%5%1
47682
Night
59%6%12%14%6%1
46668
SeeingDay
30%13%18%23%11%2
6090
Night
32%16%12%21%15%1
14459

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
47%8%4441232316%
1253
16th to endDay
40%9%35%42333419%
1481
February1st to 15thDay
39%11%37%423335%15%
1576
16th to endDay
29%13%36%6%3323422%
1436
March1st to 15thDay
45%13%35%33422312%
1891
16th to endDay
38%12%48%6%2332314%
2154
April1st to 15thDay
32%12%5%7%6%4443414%
2149
16th to endDay
31%11%47%6%35%35%5%16%
2376
May1st to 15thDay
25%9%35%5%34346%28%
2511
16th to endDay
27%9%37%6%34446%23%
2640
June1st to 15thDay
31%8%36%6%34335%23%
2700
16th to endDay
27%10%36%5%34345%24%
2700
July1st to 15thDay
14%5%25%423345%49%
2700
16th to endDay
15%5%23323335%50%
2742
August1st to 15thDay
14%5%24313345%49%
2457
16th to endDay
15%6%24433346%44%
2440
September1st to 15thDay
17%5%24322236%47%
2114
16th to endDay
32%7%25%5%2323330%
1818
October1st to 15thDay
33%8%24323345%27%
1650
16th to endDay
42%10%35%32223418%
1668
November1st to 15thDay
53%9%35%32222211%
1408
16th to endDay
43%10%3432232418%
1440
December1st to 15thDay
37%13%45%31323322%
1377
16th to endDay
47%12%35%41222213%
1344
January1st to 15thNight
43%9%2431223420%
2686
16th to endNight
37%10%35%322335%21%
2741
February1st to 15thNight
39%9%34423435%18%
2276
16th to endNight
31%11%35%422345%26%
2038
March1st to 15thNight
43%10%26%32423315%
2067
16th to endNight
38%10%36%5%3443315%
2066
April1st to 15thNight
29%10%46%5%43446%20%
1799
16th to endNight
29%10%45%6%34336%22%
1583
May1st to 15thNight
20%6%26%6%2446%5%36%
1439
16th to endNight
19%7%36%5%345%5%6%32%
1469
June1st to 15thNight
24%7%35%5%33345%32%
1260
16th to endNight
18%10%36%5%25%46%5%31%
1260
July1st to 15thNight
8%324423246%56%
1260
16th to endNight
8%213214345%60%
1427
August1st to 15thNight
8%412312345%60%
1503
16th to endNight
10%42442336%8%49%
1761
September1st to 15thNight
9%324323235%58%
1765
16th to endNight
29%6%24413346%33%
1810
October1st to 15thNight
27%6%25%43334434%
1980
16th to endNight
40%7%35%433335%20%
2201
November1st to 15thNight
50%7%35%42222314%
2450
16th to endNight
40%9%35%5%1324320%
2520
December1st to 15thNight
39%10%3432332420%
2580
16th to endNight
46%13%35%31222316%
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
47%9%3432223317%
1253
16th to endDay
40%10%2442332320%
1481
February1st to 15thDay
40%12%36%43333415%
1576
16th to endDay
30%15%46%5%2322422%
1436
March1st to 15thDay
47%13%35%43322311%
1891
16th to endDay
40%13%37%6%2332313%
2154
April1st to 15thDay
35%13%5%7%5%3433313%
2149
16th to endDay
34%12%46%6%3444416%
2376
May1st to 15thDay
28%8%25%5%24345%27%
2511
16th to endDay
31%8%36%5%34445%22%
2640
June1st to 15thDay
35%8%36%423335%23%
2700
16th to endDay
31%8%36%5%34345%24%
2700
July1st to 15thDay
17%5%24323345%48%
2700
16th to endDay
17%423323335%49%
2742
August1st to 15thDay
16%5%23313346%49%
2457
16th to endDay
17%5%24422346%43%
2440
September1st to 15thDay
18%6%23422235%47%
2114
16th to endDay
34%7%245%2223430%
1818
October1st to 15thDay
35%7%2432334427%
1650
16th to endDay
44%9%23422235%18%
1668
November1st to 15thDay
55%9%3432212211%
1408
16th to endDay
45%9%2431223418%
1440
December1st to 15thDay
38%14%4422223321%
1377
16th to endDay
47%16%25%32221213%
1344
January1st to 15thNight
44%10%2421223420%
2685
16th to endNight
39%11%3431233421%
2741
February1st to 15thNight
39%11%34323335%18%
2276
16th to endNight
32%11%25%42233326%
2038
March1st to 15thNight
44%11%3442323315%
2067
16th to endNight
40%12%35%42343316%
2070
April1st to 15thNight
30%9%46%5%34445%20%
1799
16th to endNight
32%9%36%5%24335%22%
1583
May1st to 15thNight
21%5%27%5%2435%6%35%
1439
16th to endNight
22%6%36%5%3445%7%31%
1469
June1st to 15thNight
25%7%35%5%33245%31%
1260
16th to endNight
22%8%35%4345%45%31%
1260
July1st to 15thNight
9%3245%23246%55%
1260
16th to endNight
9%313313436%59%
1427
August1st to 15thNight
9%31221235%5%60%
1503
16th to endNight
10%42432346%7%49%
1761
September1st to 15thNight
11%313323335%58%
1765
16th to endNight
30%6%15%323245%33%
1810
October1st to 15thNight
29%6%145%2333433%
1980
16th to endNight
42%7%25%433235%19%
2201
November1st to 15thNight
51%8%2442223314%
2450
16th to endNight
41%8%35%42322420%
2520
December1st to 15thNight
39%11%25%32332420%
2580
16th to endNight
47%13%3432122316%
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
73%5%6%8%5%
1253
16th to endDay
68%6%8%11%31
1481
February1st to 15thDay
73%5%8%6%42
1576
16th to endDay
67%5%9%12%5%
1436
March1st to 15thDay
79%5%6%6%1
1891
16th to endDay
76%47%9%1
2154
April1st to 15thDay
73%6%9%8%1
2149
16th to endDay
69%6%11%8%3
2376
May1st to 15thDay
57%6%13%15%5%
2511
16th to endDay
63%6%14%12%2
2644
June1st to 15thDay
63%5%16%10%41
2700
16th to endDay
60%7%13%13%5%
2700
July1st to 15thDay
38%6%15%24%12%2
2541
16th to endDay
35%7%17%26%11%1
2571
August1st to 15thDay
36%7%16%27%10%1
2440
16th to endDay
39%7%19%25%6%1
2440
September1st to 15thDay
39%6%13%22%15%2
2114
16th to endDay
59%5%10%16%7%1
1818
October1st to 15thDay
58%6%12%13%8%
1650
16th to endDay
69%5%11%9%3
1668
November1st to 15thDay
80%45%6%11
1408
16th to endDay
71%45%9%7%
1440
December1st to 15thDay
69%5%6%9%7%1
1377
16th to endDay
77%45%8%21
1344
January1st to 15thNight
68%5%414%5%
2686
16th to endNight
66%5%8%13%42
2741
February1st to 15thNight
68%6%10%8%32
2288
16th to endNight
61%410%15%6%
2038
March1st to 15thNight
74%5%9%8%2
2067
16th to endNight
73%5%10%8%2
2070
April1st to 15thNight
64%6%12%12%3
1799
16th to endNight
63%6%12%12%4
1583
May1st to 15thNight
48%8%16%17%8%1
1440
16th to endNight
51%8%20%14%4
1469
June1st to 15thNight
53%8%19%12%41
1260
16th to endNight
51%9%16%16%5%1
1260
July1st to 15thNight
31%5%16%28%15%2
1190
16th to endNight
23%8%17%32%13%3
1335
August1st to 15thNight
25%5%24%28%12%3
1495
16th to endNight
32%7%22%24%9%3
1761
September1st to 15thNight
29%6%16%23%20%3
1765
16th to endNight
53%412%19%7%2
1810
October1st to 15thNight
54%414%16%9%
1980
16th to endNight
67%6%12%9%3
2201
November1st to 15thNight
76%47%6%22
2450
16th to endNight
69%6%8%7%7%
2520
December1st to 15thNight
70%5%7%10%5%1
2580
16th to endNight
75%46%7%5%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
25%16%23%25%10%
60
16th to endDay
64%4417%10%
70
February1st to 15thDay
46%15%13%14%9%1
236
16th to endDay
37%14%17%18%9%2
214
March1st to 15thDay
55%15%16%10%1
270
16th to endDay
45%16%18%13%5%
288
April1st to 15thDay
38%17%17%15%9%1
269
16th to endDay
31%18%21%20%7%1
270
May1st to 15thDay
29%19%18%23%8%1
288
16th to endDay
24%15%21%21%10%5%
355
June1st to 15thDay
26%17%22%22%9%2
495
16th to endDay
25%17%22%21%10%1
495
July1st to 15thDay
16%13%18%35%13%1
475
16th to endDay
12%14%19%34%15%3
411
August1st to 15thDay
17%7%20%32%15%6%
315
16th to endDay
16%9%22%29%17%4
332
September1st to 15thDay
21%11%18%29%17%2
300
16th to endDay
29%11%17%24%13%4
255
October1st to 15thDay
39%8%20%19%10%1
255
16th to endDay
44%8%12%21%9%2
193
November1st to 15thDay
66%5%15%11%1
60
16th to endDay
51%10%11%10%16%
60
December1st to 15thDay
68%110%10%10%
60
16th to endDay
53%14%21%7%3
64
January1st to 15thNight
39%18%13%19%8%
750
16th to endNight
38%18%12%21%9%
778
February1st to 15thNight
38%18%15%19%7%
704
16th to endNight
32%18%18%19%10%
632
March1st to 15thNight
44%20%13%13%8%
720
16th to endNight
39%19%14%17%7%1
768
April1st to 15thNight
29%18%15%22%11%1
719
16th to endNight
30%18%15%25%7%1
503
May1st to 15thNight
21%17%11%26%21%2
360
16th to endNight
19%18%8%26%26%1
375
June1st to 15thNight
21%17%10%24%22%4
360
16th to endNight
21%17%11%25%22%1
360
July1st to 15thNight
9%13%6%29%37%4
340
16th to endNight
7%17%422%40%7%
376
August1st to 15thNight
12%9%320%43%10%
423
16th to endNight
14%9%8%25%37%5%
615
September1st to 15thNight
11%9%9%30%33%6%
706
16th to endNight
33%10%10%23%19%2
656
October1st to 15thNight
33%11%15%24%14%1
660
16th to endNight
43%10%12%23%9%
704
November1st to 15thNight
46%17%17%15%3
700
16th to endNight
40%20%14%15%8%
720
December1st to 15thNight
41%18%14%20%4
730
16th to endNight
47%19%16%13%3
800
Page generated at 2017-09-13 04:39:11. Version ac04

Copyright 2017 A. Danko


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