Smithers
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Smithers clear sky chart from 2005-11-05 to 2018-02-14.

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
37%
15249
6%
48577
4%
15221
39%
15221
13%
37823

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
22%
825
5%
2911
3%
821
25%
821
6%
2519
January16th to endNight
23%
880
7%
3120
4%
880
28%
880
7%
2633
February1st to 15thNight
31%
792
8%
2631
6%
792
35%
792
10%
2121
February16th to endNight
43%
632
11%
2053
10%
632
45%
632
15%
1521
March1st to 15thNight
31%
720
9%
2103
5%
720
35%
720
13%
1649
March16th to endNight
39%
768
7%
2112
4%
768
41%
768
14%
1674
April1st to 15thNight
39%
545
7%
1650
5%
545
41%
545
14%
1276
April16th to endNight
38%
510
7%
1590
5%
510
41%
510
13%
1234
May1st to 15thNight
43%
359
3%
1283
2%
359
44%
359
14%
927
May16th to endNight
44%
374
0%
1309
0%
374
44%
374
14%
952
June1st to 15thNight
53%
360
0%
1103
0%
360
53%
360
21%
774
June16th to endNight
47%
360
0%
919
0%
360
47%
360
21%
690
July1st to 15thNight
51%
340
0%
1111
0%
340
51%
340
21%
739
July16th to endNight
56%
376
1%
1239
0%
354
57%
354
23%
778
August1st to 15thNight
64%
423
8%
1332
7%
421
66%
421
34%
759
August16th to endNight
47%
573
8%
1719
7%
573
49%
573
19%
1234
September1st to 15thNight
53%
627
10%
1749
7%
627
53%
627
24%
1211
September16th to endNight
39%
716
9%
1980
5%
716
41%
716
13%
1584
October1st to 15thNight
41%
720
7%
2162
6%
720
43%
720
14%
1663
October16th to endNight
30%
768
5%
2550
4%
768
32%
768
8%
2105
November1st to 15thNight
30%
769
6%
2699
4%
769
33%
769
9%
2148
November16th to endNight
25%
825
6%
2925
4%
825
29%
825
8%
2432
December1st to 15thNight
31%
980
6%
3080
4%
980
33%
980
10%
2533
December16th to endNight
28%
1007
9%
3247
6%
1007
31%
1007
9%
2667

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
11%11%5%10%8%46%5%5%6%22%
49540
Night
9%12%5%9%8%46%6%6%7%22%
48719
TransparencyDay
58%9%13%14%3
49186
Night
57%9%14%14%3
48577
SeeingDay
18%13%27%25%11%2
7313
Night
15%8%24%32%16%2
15255

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
8%18%8%13%11%47%6%5%411%
1358
16th to endDay
9%16%7%12%8%5%7%6%8%6%11%
1456
February1st to 15thDay
10%14%7%11%8%46%6%5%6%18%
1533
16th to endDay
412%7%9%9%48%5%6%6%25%
1421
March1st to 15thDay
7%15%7%12%11%46%5%5%6%17%
1857
16th to endDay
6%13%6%11%9%5%7%6%7%6%17%
2112
April1st to 15thDay
9%17%7%11%9%45%5%45%18%
2297
16th to endDay
12%16%6%9%10%5%7%5%5%5%15%
2370
May1st to 15thDay
13%13%5%10%8%45%45%5%21%
2667
16th to endDay
16%11%5%9%9%45%5%46%21%
2804
June1st to 15thDay
12%9%410%7%46%5%5%6%27%
2853
16th to endDay
16%9%5%8%7%45%5%5%6%24%
3038
July1st to 15thDay
10%7%49%8%46%5%5%6%31%
2778
16th to endDay
9%6%37%8%36%5%6%8%32%
2846
August1st to 15thDay
8%426%6%45%6%6%8%41%
2618
16th to endDay
14%10%49%9%45%5%5%6%25%
2483
September1st to 15thDay
11%8%48%8%45%5%7%8%27%
2209
16th to endDay
16%11%49%7%47%6%5%6%19%
1980
October1st to 15thDay
15%13%37%8%46%45%7%21%
1797
16th to endDay
17%13%5%8%6%48%5%5%6%17%
1674
November1st to 15thDay
11%14%5%10%9%5%7%5%6%6%17%
1489
16th to endDay
8%14%6%12%10%5%8%7%5%6%14%
1365
December1st to 15thDay
6%11%6%15%12%46%7%5%5%16%
1196
16th to endDay
6%15%9%11%9%6%6%6%5%7%14%
1339
January1st to 15thNight
8%19%9%14%10%46%445%12%
2911
16th to endNight
10%16%6%12%10%5%7%6%6%7%12%
3120
February1st to 15thNight
10%17%6%11%8%4446%6%19%
2619
16th to endNight
5%12%6%9%8%47%6%6%7%25%
2053
March1st to 15thNight
6%12%8%9%7%6%7%6%6%7%21%
2103
16th to endNight
6%13%6%9%8%5%7%8%6%8%20%
2108
April1st to 15thNight
9%13%410%8%46%6%6%7%23%
1650
16th to endNight
7%14%6%9%7%47%5%5%8%22%
1590
May1st to 15thNight
11%9%5%9%6%45%5%5%7%28%
1282
16th to endNight
15%10%36%5%36%5%7%8%27%
1309
June1st to 15thNight
6%7%46%7%46%7%7%9%32%
1103
16th to endNight
12%7%46%5%36%7%6%8%31%
919
July1st to 15thNight
9%5%25%7%36%6%6%9%38%
1179
16th to endNight
5%4246%46%6%7%9%41%
1323
August1st to 15thNight
6%2135%245%5%8%52%
1339
16th to endNight
10%6%38%8%35%46%8%33%
1719
September1st to 15thNight
9%6%37%7%45%5%5%8%38%
1749
16th to endNight
12%9%49%7%46%8%6%5%24%
1980
October1st to 15thNight
16%10%47%6%35%5%5%6%28%
2162
16th to endNight
16%15%5%8%7%46%5%6%6%16%
2550
November1st to 15thNight
12%14%48%8%5%6%6%6%7%17%
2699
16th to endNight
7%16%7%12%10%6%6%5%5%7%14%
2925
December1st to 15thNight
8%13%7%11%11%5%6%5%6%6%17%
3080
16th to endNight
6%14%9%13%10%5%6%6%6%6%14%
3247

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
72%10%9%7%
1358
16th to endDay
67%8%9%9%3
1456
February1st to 15thDay
61%10%9%10%7%
1533
16th to endDay
55%9%13%14%6%
1421
March1st to 15thDay
64%8%10%12%2
1857
16th to endDay
61%9%14%11%2
2112
April1st to 15thDay
66%8%9%13%1
2297
16th to endDay
68%7%10%9%3
2370
May1st to 15thDay
63%6%10%14%4
2667
16th to endDay
62%7%14%13%1
2808
June1st to 15thDay
56%7%15%14%5%
2853
16th to endDay
57%9%14%15%2
3038
July1st to 15thDay
50%9%15%20%4
2617
16th to endDay
45%10%22%20%1
2667
August1st to 15thDay
38%10%19%26%5%
2600
16th to endDay
56%11%16%13%2
2483
September1st to 15thDay
50%10%18%17%2
2209
16th to endDay
62%9%12%12%2
1980
October1st to 15thDay
59%10%15%11%3
1797
16th to endDay
63%10%12%11%1
1674
November1st to 15thDay
64%7%11%12%2
1489
16th to endDay
64%11%11%9%3
1365
December1st to 15thDay
64%10%8%12%3
1196
16th to endDay
63%10%8%13%4
1339
January1st to 15thNight
72%8%9%8%1
2911
16th to endNight
68%9%9%8%4
3120
February1st to 15thNight
64%7%8%11%8%
2631
16th to endNight
54%8%14%16%6%
2053
March1st to 15thNight
58%9%13%15%21
2103
16th to endNight
58%9%14%15%2
2112
April1st to 15thNight
56%9%14%16%3
1650
16th to endNight
58%8%14%15%3
1590
May1st to 15thNight
53%8%17%15%4
1283
16th to endNight
53%8%19%16%2
1309
June1st to 15thNight
44%10%19%20%4
1103
16th to endNight
48%10%17%20%3
919
July1st to 15thNight
40%11%19%23%4
1111
16th to endNight
34%12%28%21%2
1239
August1st to 15thNight
27%9%27%29%6%
1332
16th to endNight
46%11%21%19%1
1719
September1st to 15thNight
41%10%22%20%4
1749
16th to endNight
56%11%12%15%2
1980
October1st to 15thNight
54%10%15%14%4
2162
16th to endNight
62%12%13%10%1
2550
November1st to 15thNight
59%11%13%12%2
2699
16th to endNight
66%9%9%11%3
2925
December1st to 15thNight
63%9%12%11%3
3080
16th to endNight
65%8%9%11%4
3247

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
12%223%31%26%4
90
16th to endDay
19%10%15%29%17%7%
96
February1st to 15thDay
22%8%25%29%11%1
270
16th to endDay
13%11%30%30%10%3
211
March1st to 15thDay
20%23%34%15%6%
252
16th to endDay
17%16%29%26%9%1
288
April1st to 15thDay
21%14%33%17%9%2
269
16th to endDay
25%24%22%18%7%1
270
May1st to 15thDay
24%17%24%24%8%1
444
16th to endDay
19%16%24%28%8%2
518
June1st to 15thDay
15%12%32%25%13%
612
16th to endDay
18%10%26%27%14%3
653
July1st to 15thDay
15%16%30%25%10%1
475
16th to endDay
12%12%33%27%12%2
515
August1st to 15thDay
9%10%24%33%17%5%
478
16th to endDay
22%14%32%22%6%
332
September1st to 15thDay
17%15%26%21%13%3
315
16th to endDay
25%11%29%20%10%2
315
October1st to 15thDay
24%14%28%16%12%3
310
16th to endDay
27%13%22%22%11%2
234
November1st to 15thDay
22%11%13%31%12%10%
90
16th to endDay
10%7%23%30%20%8%
90
December1st to 15thDay
8%217%35%26%8%
90
16th to endDay
6%5%19%37%23%7%
96
January1st to 15thNight
17%9%26%31%13%1
825
16th to endNight
20%8%27%30%11%1
880
February1st to 15thNight
17%8%27%30%14%1
796
16th to endNight
11%7%21%38%17%3
632
March1st to 15thNight
13%14%30%27%12%1
720
16th to endNight
12%10%23%29%20%4
768
April1st to 15thNight
15%8%21%27%22%3
545
16th to endNight
14%9%27%26%20%1
510
May1st to 15thNight
15%7%21%34%19%1
360
16th to endNight
19%7%20%30%20%1
375
June1st to 15thNight
8%5%21%43%20%1
360
16th to endNight
15%6%22%37%17%1
360
July1st to 15thNight
12%5%22%40%17%1
340
16th to endNight
7%423%43%18%2
376
August1st to 15thNight
8%315%32%36%2
423
16th to endNight
13%423%39%18%
573
September1st to 15thNight
12%8%18%33%21%4
627
16th to endNight
18%7%23%31%16%2
716
October1st to 15thNight
22%9%18%31%15%3
720
16th to endNight
25%8%21%29%13%1
768
November1st to 15thNight
20%10%28%26%12%1
769
16th to endNight
17%9%30%29%12%1
825
December1st to 15thNight
14%8%27%32%14%2
980
16th to endNight
13%8%27%33%15%2
1007
Page generated at 2018-02-15 07:58:51. Version ac04

Copyright 2018 A. Danko


Smithers Clear Sky Chart |Charts Home