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 2017-09-10.

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
35%
14445
9%
46627
7%
14417
37%
14417
12%
35012

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%
750
10%
2686
9%
746
29%
746
8%
2185
January16th to endNight
28%
773
8%
2715
7%
773
31%
773
9%
2144
February1st to 15thNight
20%
700
5%
2288
2%
700
24%
700
7%
1899
February16th to endNight
26%
632
13%
2026
8%
632
33%
632
11%
1545
March1st to 15thNight
21%
720
4%
2079
3%
720
22%
720
8%
1742
March16th to endNight
23%
768
5%
2059
2%
768
24%
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
42%
359
11%
1439
17%
359
45%
359
14%
949
May16th to endNight
44%
374
5%
1496
8%
374
47%
374
12%
1037
June1st to 15thNight
44%
360
2%
1264
1%
360
44%
360
14%
923
June16th to endNight
48%
360
5%
1260
2%
360
48%
360
15%
861
July1st to 15thNight
64%
340
10%
1190
9%
340
65%
340
29%
661
July16th to endNight
66%
376
15%
1358
21%
354
74%
354
35%
645
August1st to 15thNight
70%
411
16%
1483
21%
409
71%
409
35%
723
August16th to endNight
65%
629
18%
1775
14%
629
67%
629
34%
1033
September1st to 15thNight
65%
700
18%
1750
10%
700
66%
700
37%
1070
September16th to endNight
44%
656
17%
1804
12%
656
47%
656
20%
1299
October1st to 15thNight
39%
660
10%
1980
9%
660
42%
660
17%
1417
October16th to endNight
31%
704
5%
2194
4%
704
33%
704
9%
1747
November1st to 15thNight
21%
700
5%
2448
4%
700
23%
700
6%
2093
November16th to endNight
21%
720
6%
2520
4%
720
24%
720
7%
2052
December1st to 15thNight
21%
724
8%
2544
5%
724
26%
724
8%
2053
December16th to endNight
14%
800
5%
2880
3%
800
17%
800
5%
2425

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%
48017
Night
29%8%35%423335%29%
46784
Cloud CoverDay
26%9%36%5%24345%29%
48017
Night
29%8%35%423345%28%
46787
TransparencyDay
58%5%12%15%6%1
47677
Night
58%5%13%15%6%1
46628
SeeingDay
24%16%19%24%11%3
6014
Night
28%18%10%20%17%3
14451

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
42%9%3442432418%
1253
16th to endDay
37%10%35%322335%20%
1508
February1st to 15thDay
36%10%37%5%24235%17%
1573
16th to endDay
29%11%46%6%2433423%
1448
March1st to 15thDay
41%11%47%5%1333314%
1878
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%1442324451%
2097
16th to endDay
25%8%36%5%2334432%
1822
October1st to 15thDay
26%8%35%5%2345%5%28%
1650
16th to endDay
37%7%26%5%2225%6%20%
1677
November1st to 15thDay
47%9%46%41324313%
1408
16th to endDay
38%11%36%32323420%
1440
December1st to 15thDay
33%14%47%31232322%
1413
16th to endDay
42%11%45%5%2323214%
1344
January1st to 15thNight
43%8%2442222421%
2686
16th to endNight
36%12%35%312235%22%
2715
February1st to 15thNight
37%10%37%5%2333418%
2276
16th to endNight
28%10%45%42333427%
2026
March1st to 15thNight
37%10%37%424445%17%
2079
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
10%323324346%56%
1750
16th to endNight
22%7%25%5%23346%36%
1804
October1st to 15thNight
24%7%2442444435%
1980
16th to endNight
35%8%35%5%23336%21%
2194
November1st to 15thNight
46%8%35%42333414%
2448
16th to endNight
40%8%36%42323321%
2520
December1st to 15thNight
36%10%35%41334422%
2544
16th to endNight
42%13%35%31222317%
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
40%10%35%32333419%
1253
16th to endDay
37%10%35%322335%20%
1508
February1st to 15thDay
34%11%47%434345%17%
1573
16th to endDay
28%12%35%5%3433423%
1448
March1st to 15thDay
38%12%47%5%2433213%
1878
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%7%25%41233451%
2097
16th to endDay
25%7%36%5%2443432%
1822
October1st to 15thDay
26%8%25%5%3445%5%29%
1650
16th to endDay
37%6%35%5%23346%20%
1677
November1st to 15thDay
46%10%36%42313412%
1408
16th to endDay
37%12%35%33323420%
1440
December1st to 15thDay
32%14%47%42323222%
1413
16th to endDay
40%13%47%5%2312214%
1344
January1st to 15thNight
42%9%3431222421%
2685
16th to endNight
35%12%34313335%22%
2715
February1st to 15thNight
36%10%37%5%3423418%
2276
16th to endNight
28%11%36%5%2323427%
2026
March1st to 15thNight
36%11%36%5%23435%17%
2079
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
10%412324346%56%
1750
16th to endNight
22%6%35%5%23346%36%
1804
October1st to 15thNight
24%7%2443444435%
1980
16th to endNight
34%8%36%423336%21%
2194
November1st to 15thNight
45%8%35%42334414%
2448
16th to endNight
40%8%35%41333420%
2520
December1st to 15thNight
35%11%35%42333422%
2544
16th to endNight
42%13%45%42222216%
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
70%5%6%9%6%
1253
16th to endDay
65%6%9%12%31
1508
February1st to 15thDay
71%5%8%6%6%1
1573
16th to endDay
65%39%14%5%1
1448
March1st to 15thDay
76%48%8%1
1878
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
37%414%21%18%2
2097
16th to endDay
56%5%10%15%9%1
1822
October1st to 15thDay
56%414%14%8%1
1650
16th to endDay
65%5%13%12%3
1677
November1st to 15thDay
77%38%7%11
1408
16th to endDay
70%37%9%7%1
1440
December1st to 15thDay
69%47%9%8%
1413
16th to endDay
77%35%8%31
1344
January1st to 15thNight
68%5%6%13%5%
2686
16th to endNight
65%49%13%42
2715
February1st to 15thNight
71%410%8%32
2288
16th to endNight
62%310%16%6%1
2026
March1st to 15thNight
69%5%12%9%3
2079
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
29%6%17%22%20%3
1750
16th to endNight
50%5%12%20%7%3
1804
October1st to 15thNight
51%6%15%17%8%1
1980
16th to endNight
64%5%14%11%4
2194
November1st to 15thNight
73%5%8%7%22
2448
16th to endNight
69%49%8%7%
2520
December1st to 15thNight
66%6%9%11%5%
2544
16th to endNight
74%38%7%41
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%10%23%18%28%8%
60
16th to endDay
54%310%17%10%3
64
February1st to 15thDay
39%19%18%11%9%2
233
16th to endDay
32%18%20%15%10%1
216
March1st to 15thDay
46%23%15%12%1
270
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
17%14%21%22%18%5%
294
16th to endDay
21%11%19%28%14%4
255
October1st to 15thDay
33%12%19%20%12%
255
16th to endDay
38%12%17%20%7%2
189
November1st to 15thDay
58%11%18%10%1
60
16th to endDay
41%6%18%10%13%10%
60
December1st to 15thDay
50%11%20%11%33
60
16th to endDay
43%121%23%6%3
64
January1st to 15thNight
37%21%9%15%14%1
750
16th to endNight
33%20%10%20%13%1
773
February1st to 15thNight
37%22%12%16%9%1
704
16th to endNight
28%22%15%18%12%2
632
March1st to 15thNight
36%22%14%15%10%
720
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
11%10%6%29%31%11%
700
16th to endNight
25%12%8%23%24%5%
656
October1st to 15thNight
26%11%15%23%18%4
660
16th to endNight
35%13%11%23%12%3
704
November1st to 15thNight
42%18%11%20%5%1
700
16th to endNight
38%21%11%16%10%1
720
December1st to 15thNight
35%23%13%19%5%
724
16th to endNight
42%21%16%14%4
800
Page generated at 2017-09-11 16:35:14. Version ac04

Copyright 2017 A. Danko


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