Abbotsford
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Abbotsford clear sky chart from 2005-11-05 to 2018-03-11.

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
34%
15208
9%
49035
7%
15180
37%
15180
12%
36915

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
26%
825
9%
2911
8%
821
29%
821
8%
2362
January16th to endNight
26%
839
8%
2941
6%
839
29%
839
8%
2362
February1st to 15thNight
20%
760
6%
2483
3%
760
24%
760
7%
2061
February16th to endNight
26%
684
13%
2193
8%
684
34%
684
11%
1679
March1st to 15thNight
23%
764
4%
2208
3%
764
24%
764
9%
1830
March16th to endNight
22%
768
5%
2059
2%
768
23%
768
8%
1754
April1st to 15thNight
29%
719
5%
1799
3%
719
30%
719
11%
1493
April16th to endNight
31%
510
7%
1590
5%
510
33%
510
10%
1262
May1st to 15thNight
43%
359
11%
1439
17%
359
46%
359
14%
949
May16th to endNight
44%
374
5%
1496
8%
374
47%
374
12%
1037
June1st to 15thNight
43%
360
2%
1264
1%
360
44%
360
14%
923
June16th to endNight
47%
360
5%
1260
2%
360
48%
360
15%
861
July1st to 15thNight
63%
340
10%
1190
9%
340
64%
340
29%
661
July16th to endNight
67%
376
15%
1358
21%
354
75%
354
35%
645
August1st to 15thNight
71%
411
16%
1483
21%
409
72%
409
35%
723
August16th to endNight
65%
629
18%
1775
14%
629
67%
629
34%
1033
September1st to 15thNight
65%
720
19%
1800
10%
720
67%
720
38%
1090
September16th to endNight
46%
716
17%
1968
13%
716
48%
716
20%
1421
October1st to 15thNight
40%
720
10%
2160
9%
720
42%
720
18%
1537
October16th to endNight
32%
768
7%
2394
7%
768
35%
768
10%
1876
November1st to 15thNight
20%
760
4%
2658
4%
760
22%
760
6%
2283
November16th to endNight
20%
780
5%
2730
4%
780
23%
780
6%
2261
December1st to 15thNight
24%
786
9%
2756
6%
786
29%
786
9%
2182
December16th to endNight
14%
880
6%
3120
3%
880
17%
880
5%
2630

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
27%8%36%5%24345%29%
49610
Night
30%8%35%423335%28%
49192
Cloud CoverDay
27%9%36%5%24345%29%
49610
Night
29%8%35%423345%28%
49195
TransparencyDay
58%5%12%15%6%1
49270
Night
58%5%12%14%6%1
49036
SeeingDay
25%15%19%23%11%3
6523
Night
29%17%10%20%17%3
15214

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
41%9%35%42422418%
1358
16th to endDay
39%10%35%322335%19%
1634
February1st to 15thDay
37%9%37%5%2423417%
1708
16th to endDay
29%12%46%5%2333423%
1567
March1st to 15thDay
40%11%47%5%2333314%
1985
16th to endDay
33%12%47%7%4443315%
2164
April1st to 15thDay
31%10%48%6%45%34415%
2149
16th to endDay
27%10%5%7%6%35%35%5%17%
2367
May1st to 15thDay
24%7%35%5%24435%30%
2511
16th to endDay
25%9%37%6%34346%24%
2615
June1st to 15thDay
29%8%46%5%34445%24%
2694
16th to endDay
23%8%46%5%45%335%28%
2700
July1st to 15thDay
12%5%25%41334452%
2700
16th to endDay
12%423413335%54%
2714
August1st to 15thDay
12%5%13323346%52%
2466
16th to endDay
13%5%14423447%46%
2426
September1st to 15thDay
14%6%1442224451%
2160
16th to endDay
24%8%37%5%2334432%
1988
October1st to 15thDay
25%8%35%5%2335%5%30%
1800
16th to endDay
37%7%26%5%2225%5%21%
1829
November1st to 15thDay
46%9%46%42324313%
1528
16th to endDay
40%10%35%42323418%
1560
December1st to 15thDay
32%13%37%42232324%
1531
16th to endDay
43%11%46%5%2312215%
1456
January1st to 15thNight
43%8%2442222421%
2911
16th to endNight
38%12%35%312235%20%
2941
February1st to 15thNight
38%10%36%5%2333418%
2471
16th to endNight
29%11%45%42333427%
2193
March1st to 15thNight
36%9%37%42443419%
2208
16th to endNight
35%11%36%5%3434417%
2055
April1st to 15thNight
28%10%37%6%44445%20%
1799
16th to endNight
30%9%47%5%24435%21%
1590
May1st to 15thNight
20%6%37%42345%6%35%
1439
16th to endNight
19%6%35%6%35%45%7%31%
1496
June1st to 15thNight
20%8%46%5%44345%31%
1264
16th to endNight
17%7%36%5%25%5%5%6%33%
1260
July1st to 15thNight
8%5%2342233458%
1260
16th to endNight
9%212222346%62%
1453
August1st to 15thNight
9%31221335%6%60%
1491
16th to endNight
7%42442436%8%50%
1775
September1st to 15thNight
9%323324346%57%
1800
16th to endNight
21%7%25%5%33345%36%
1968
October1st to 15thNight
24%6%2442444436%
2160
16th to endNight
34%8%25%5%23335%23%
2394
November1st to 15thNight
46%8%35%42333414%
2658
16th to endNight
42%8%36%42323319%
2730
December1st to 15thNight
35%10%3431334423%
2756
16th to endNight
43%13%35%31222217%
3120

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
40%9%35%42333419%
1358
16th to endDay
39%10%35%322335%19%
1634
February1st to 15thDay
36%10%36%43333417%
1708
16th to endDay
28%13%45%5%3333423%
1567
March1st to 15thDay
37%12%47%5%2433214%
1985
16th to endDay
32%13%47%7%35%33314%
2164
April1st to 15thDay
30%12%48%7%35%44415%
2149
16th to endDay
27%11%48%6%36%35%5%17%
2367
May1st to 15thDay
24%7%36%5%33435%30%
2511
16th to endDay
27%10%37%5%3435%6%23%
2615
June1st to 15thDay
29%8%37%5%34345%24%
2694
16th to endDay
23%9%46%5%25%435%28%
2700
July1st to 15thDay
12%6%24323345%51%
2700
16th to endDay
12%423422345%53%
2714
August1st to 15thDay
12%41342335%6%51%
2466
16th to endDay
13%5%24433347%46%
2426
September1st to 15thDay
13%6%25%41233452%
2160
16th to endDay
25%7%36%5%3443432%
1988
October1st to 15thDay
25%8%25%5%3345%5%30%
1800
16th to endDay
37%6%35%5%23346%22%
1829
November1st to 15thDay
45%10%36%42323412%
1528
16th to endDay
39%11%35%43323418%
1560
December1st to 15thDay
31%13%46%42333224%
1531
16th to endDay
41%12%47%42312215%
1456
January1st to 15thNight
42%8%3431222422%
2910
16th to endNight
36%13%35%312235%21%
2941
February1st to 15thNight
37%10%36%5%3323418%
2471
16th to endNight
28%12%36%5%2323427%
2193
March1st to 15thNight
35%11%36%5%23435%19%
2208
16th to endNight
34%11%46%5%2433417%
2059
April1st to 15thNight
27%11%36%6%35%445%20%
1799
16th to endNight
30%9%47%6%3444421%
1590
May1st to 15thNight
19%6%38%5%2445%6%34%
1439
16th to endNight
19%6%36%6%45%46%6%30%
1496
June1st to 15thNight
21%8%37%6%44445%31%
1264
16th to endNight
18%7%35%6%35%5%5%6%32%
1260
July1st to 15thNight
8%5%2442334457%
1260
16th to endNight
8%32312346%62%
1453
August1st to 15thNight
9%32221235%6%60%
1491
16th to endNight
7%3245%2445%8%50%
1775
September1st to 15thNight
9%412323346%57%
1800
16th to endNight
21%7%35%5%23345%36%
1968
October1st to 15thNight
23%7%2442444435%
2160
16th to endNight
34%7%36%423336%23%
2394
November1st to 15thNight
44%9%36%42334414%
2658
16th to endNight
41%8%35%5%2333419%
2730
December1st to 15thNight
33%11%35%423335%24%
2756
16th to endNight
42%14%45%32222217%
3120

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
70%5%6%10%6%
1358
16th to endDay
67%6%8%12%31
1634
February1st to 15thDay
71%5%8%6%6%1
1708
16th to endDay
65%38%14%5%1
1567
March1st to 15thDay
75%49%9%1
1985
16th to endDay
75%48%10%1
2164
April1st to 15thDay
71%5%11%10%1
2149
16th to endDay
67%5%11%10%4
2367
May1st to 15thDay
55%414%16%7%
2511
16th to endDay
61%6%17%12%2
2619
June1st to 15thDay
62%415%12%41
2694
16th to endDay
57%5%14%16%4
2700
July1st to 15thDay
35%5%15%27%12%3
2541
16th to endDay
32%418%31%11%2
2546
August1st to 15thDay
33%5%19%30%9%1
2449
16th to endDay
36%5%20%27%7%1
2426
September1st to 15thDay
36%414%21%18%3
2160
16th to endDay
56%5%11%15%9%1
1988
October1st to 15thDay
55%414%14%9%1
1800
16th to endDay
64%5%12%12%5%
1829
November1st to 15thDay
77%38%7%21
1528
16th to endDay
71%47%8%7%
1560
December1st to 15thDay
67%47%10%9%1
1531
16th to endDay
77%348%41
1456
January1st to 15thNight
68%46%14%5%
2911
16th to endNight
67%49%12%42
2941
February1st to 15thNight
71%49%8%33
2483
16th to endNight
62%310%16%6%1
2193
March1st to 15thNight
68%5%12%10%3
2208
16th to endNight
71%5%11%10%1
2059
April1st to 15thNight
66%5%13%11%2
1799
16th to endNight
65%412%13%4
1590
May1st to 15thNight
48%5%17%17%8%1
1440
16th to endNight
51%7%22%14%3
1496
June1st to 15thNight
55%5%19%13%41
1264
16th to endNight
49%6%19%19%41
1260
July1st to 15thNight
31%6%13%29%16%3
1190
16th to endNight
23%5%18%32%16%3
1358
August1st to 15thNight
24%5%21%33%11%3
1483
16th to endNight
31%422%27%11%2
1775
September1st to 15thNight
28%6%17%22%20%4
1800
16th to endNight
50%5%12%20%8%2
1968
October1st to 15thNight
50%6%15%17%9%1
2160
16th to endNight
63%5%13%12%5%
2394
November1st to 15thNight
74%5%8%6%22
2658
16th to endNight
71%48%7%6%
2730
December1st to 15thNight
63%6%9%11%6%1
2756
16th to endNight
74%38%7%41
3120

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
22%8%17%15%23%12%
90
16th to endDay
58%8%11%12%7%2
96
February1st to 15thDay
42%16%18%12%8%2
278
16th to endDay
35%17%24%14%8%1
257
March1st to 15thDay
44%20%15%15%31
312
16th to endDay
35%22%20%15%5%
288
April1st to 15thDay
33%19%20%15%10%1
269
16th to endDay
22%22%24%20%6%2
270
May1st to 15thDay
24%17%23%22%8%2
288
16th to endDay
26%18%13%22%14%5%
330
June1st to 15thDay
19%20%19%26%10%3
489
16th to endDay
18%19%21%28%9%2
495
July1st to 15thDay
13%12%19%37%14%3
475
16th to endDay
8%15%19%32%18%4
383
August1st to 15thDay
13%8%19%30%18%9%
315
16th to endDay
9%13%18%35%15%7%
332
September1st to 15thDay
16%13%21%23%19%5%
315
16th to endDay
20%10%19%28%15%5%
315
October1st to 15thDay
31%11%20%22%13%1
315
16th to endDay
40%11%16%19%10%2
245
November1st to 15thDay
54%12%18%11%21
90
16th to endDay
48%7%17%10%8%6%
90
December1st to 15thDay
40%7%15%8%13%14%
90
16th to endDay
46%321%19%6%2
96
January1st to 15thNight
38%19%9%15%15%1
825
16th to endNight
35%19%10%19%12%1
839
February1st to 15thNight
39%21%12%16%9%1
764
16th to endNight
29%21%16%18%12%1
684
March1st to 15thNight
36%20%14%15%11%1
764
16th to endNight
33%22%12%20%8%3
768
April1st to 15thNight
27%21%11%21%14%2
719
16th to endNight
31%20%9%22%13%1
510
May1st to 15thNight
19%20%8%23%24%3
360
16th to endNight
18%18%7%21%28%5%
375
June1st to 15thNight
17%19%9%21%24%7%
360
16th to endNight
18%18%7%24%27%3
360
July1st to 15thNight
10%15%424%39%5%
340
16th to endNight
6%17%5%19%40%10%
376
August1st to 15thNight
9%10%315%43%17%
411
16th to endNight
10%10%5%23%41%9%
629
September1st to 15thNight
10%10%6%30%31%11%
720
16th to endNight
23%12%8%24%25%5%
716
October1st to 15thNight
26%10%14%24%18%4
720
16th to endNight
34%12%11%23%14%3
768
November1st to 15thNight
44%17%12%19%5%1
760
16th to endNight
39%21%11%16%9%1
780
December1st to 15thNight
34%22%13%19%8%1
786
16th to endNight
43%20%16%14%4
880
Page generated at 2018-03-12 10:28:10. Version ac04

Copyright 2018 A. Danko


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