Kitchener-Waterloo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kitchener-Waterloo clear sky chart from 2005-11-06 to 2024-03-28.

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
31%
23195
13%
80512
9%
23092
38%
23092
15%
58094

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 10thNight
13%
752
7%
4351
4%
737
21%
737
4%
3533
January11th to 20thNight
13%
758
4%
4115
2%
740
17%
740
3%
3477
January21st to endNight
18%
833
6%
4528
4%
814
25%
814
6%
3701
February1st to 10thNight
15%
760
8%
2470
4%
760
20%
760
9%
1956
February11th to 20thNight
18%
741
10%
2405
3%
740
27%
740
11%
1804
February21st to endNight
17%
628
10%
1937
2%
628
24%
628
11%
1473
March1st to 10thNight
21%
760
16%
2114
7%
760
28%
760
18%
1536
March11th to 20thNight
22%
760
16%
2090
7%
760
31%
760
18%
1510
March21st to endNight
27%
821
17%
2256
8%
821
34%
821
20%
1608
April1st to 10thNight
25%
720
14%
1878
5%
720
31%
720
20%
1376
April11th to 20thNight
30%
603
19%
1667
8%
603
36%
603
22%
1154
April21st to endNight
32%
540
17%
1620
7%
540
39%
540
20%
1112
May1st to 10thNight
36%
540
16%
1620
9%
540
43%
540
23%
1093
May11th to 20thNight
39%
449
19%
1511
10%
449
50%
449
23%
942
May21st to endNight
51%
388
18%
1551
17%
388
60%
388
28%
829
June1st to 10thNight
45%
360
15%
1440
13%
360
56%
360
24%
842
June11th to 20thNight
45%
360
17%
1330
17%
360
53%
360
25%
773
June21st to endNight
47%
360
16%
1260
15%
360
55%
360
26%
752
July1st to 10thNight
64%
350
19%
1229
23%
350
69%
350
38%
628
July11th to 20thNight
55%
417
18%
1461
19%
417
60%
417
32%
797
July21st to endNight
59%
591
16%
1672
12%
558
63%
558
33%
1011
August1st to 10thNight
61%
537
18%
1600
13%
534
65%
534
33%
967
August11th to 20thNight
64%
534
23%
1598
16%
534
69%
534
36%
930
August21st to endNight
54%
632
21%
1820
12%
632
58%
632
32%
1136
September1st to 10thNight
54%
720
18%
1800
10%
720
57%
720
32%
1189
September11th to 20thNight
55%
720
26%
1970
17%
720
61%
720
37%
1178
September21st to endNight
44%
720
20%
1980
14%
720
49%
720
25%
1346
October1st to 10thNight
39%
720
18%
2155
14%
720
44%
720
23%
1448
October11th to 20thNight
31%
720
15%
2160
9%
720
40%
720
19%
1531
October21st to endNight
23%
792
15%
2376
9%
792
32%
792
13%
1796
November1st to 10thNight
33%
740
16%
2439
14%
740
39%
740
18%
1649
November11th to 20thNight
21%
760
12%
2660
7%
760
30%
760
12%
1938
November21st to endNight
20%
760
9%
2660
5%
760
24%
760
11%
2008
December1st to 10thNight
14%
760
5%
2660
2%
760
17%
760
6%
2168
December11th to 20thNight
13%
760
6%
3253
1%
758
20%
758
6%
2562
December21st to endNight
10%
829
3%
4876
1%
817
15%
817
3%
4341

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
15%10%48%7%45%5%6%7%30%
79217
Night
15%10%5%8%6%45%5%5%7%31%
80756
TransparencyDay
52%8%13%17%9%1
78930
Night
52%8%12%18%9%1
80578
SeeingDay
19%14%29%22%12%5%
13992
Night
19%12%30%27%10%1
23218

By Month

Percentage Cloud Cover NE (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 10thDay
16%18%7%11%8%34345%21%
2579
11th to 20thDay
11%18%8%16%11%45%5%5%5%11%
2840
21st to endDay
21%18%8%12%8%45%43412%
3124
February1st to 10thDay
15%16%6%10%10%5%7%5%5%5%16%
1710
11th to 20thDay
13%12%8%13%9%4446%7%20%
1663
21st to endDay
16%14%6%9%9%45%45%5%22%
1513
March1st to 10thDay
14%13%5%9%7%45%46%6%28%
2062
11th to 20thDay
13%11%5%9%6%45%5%5%6%30%
2090
21st to endDay
18%11%48%7%35%446%30%
2255
April1st to 10thDay
17%11%5%8%6%445%6%6%27%
2081
11th to 20thDay
18%10%35%5%3445%6%35%
2258
21st to endDay
20%10%37%5%44446%32%
2340
May1st to 10thDay
17%9%37%7%345%5%8%33%
2340
11th to 20thDay
16%7%46%6%35%5%5%7%37%
2379
21st to endDay
12%5%35%5%45%5%6%10%41%
2725
June1st to 10thDay
13%6%25%5%36%6%6%9%37%
2520
11th to 20thDay
11%5%36%5%35%6%7%8%41%
2623
21st to endDay
13%5%26%5%35%6%6%9%40%
2700
July1st to 10thDay
8%425%5%35%6%7%9%45%
2692
11th to 20thDay
12%5%25%5%46%6%8%10%36%
2448
21st to endDay
9%6%37%7%46%5%7%10%38%
2547
August1st to 10thDay
9%5%25%6%47%6%7%11%38%
2327
11th to 20thDay
9%6%37%6%46%7%7%9%37%
2303
21st to endDay
12%6%36%6%35%6%6%8%39%
2516
September1st to 10thDay
12%6%26%6%45%6%6%9%38%
2160
11th to 20thDay
12%5%35%6%3447%10%42%
1986
21st to endDay
15%6%36%7%36%5%7%7%36%
1980
October1st to 10thDay
19%9%37%6%345%6%7%32%
1805
11th to 20thDay
22%9%37%7%35%5%5%6%28%
1800
21st to endDay
24%11%48%6%45%6%5%7%20%
1977
November1st to 10thDay
13%10%48%6%36%5%5%7%30%
1636
11th to 20thDay
15%13%5%9%7%35%5%7%7%23%
1520
21st to endDay
17%15%8%10%7%345%6%6%19%
1520
December1st to 10thDay
14%17%7%12%8%46%6%5%6%14%
1520
11th to 20thDay
18%16%7%11%8%46%6%5%5%15%
1906
21st to endDay
29%18%6%12%8%443438%
2772
January1st to 10thNight
17%16%7%13%7%46%445%16%
4365
11th to 20thNight
14%14%7%13%11%6%6%6%6%5%12%
4120
21st to endNight
21%14%9%11%8%44445%16%
4532
February1st to 10thNight
15%14%6%10%8%46%5%5%7%20%
2470
11th to 20thNight
14%12%6%10%8%46%5%5%7%24%
2403
21st to endNight
15%11%6%10%8%45%5%5%6%24%
1937
March1st to 10thNight
14%9%38%7%46%5%5%7%32%
2104
11th to 20thNight
14%10%48%7%35%5%5%7%33%
2089
21st to endNight
16%11%47%6%34445%36%
2256
April1st to 10thNight
19%8%37%6%35%45%6%33%
1878
11th to 20thNight
16%9%36%5%3445%6%38%
1667
21st to endNight
15%9%37%6%35%45%7%35%
1620
May1st to 10thNight
16%7%37%5%3446%7%38%
1620
11th to 20thNight
15%6%25%6%246%5%7%42%
1510
21st to endNight
9%424435%45%9%51%
1550
June1st to 10thNight
10%5%35%5%35%5%6%7%46%
1440
11th to 20thNight
11%425%6%35%5%6%8%44%
1330
21st to endNight
10%5%346%35%5%5%8%46%
1260
July1st to 10thNight
5%324435%45%9%58%
1264
11th to 20thNight
9%425%4235%5%10%50%
1509
21st to endNight
8%425%5%35%5%6%9%49%
1771
August1st to 10thNight
8%6%25%445%46%9%49%
1611
11th to 20thNight
6%4244345%7%10%50%
1598
21st to endNight
9%6%245%345%5%8%48%
1820
September1st to 10thNight
10%5%25%6%36%5%5%7%45%
1800
11th to 20thNight
11%5%2442446%7%53%
1970
21st to endNight
15%6%26%6%35%45%8%41%
1980
October1st to 10thNight
16%7%46%5%3445%7%39%
2155
11th to 20thNight
17%9%37%6%3446%6%34%
2160
21st to endNight
22%9%47%6%35%5%5%6%27%
2376
November1st to 10thNight
14%9%37%6%346%6%6%36%
2439
11th to 20thNight
15%12%48%7%45%5%6%8%26%
2660
21st to endNight
18%12%5%8%7%45%5%5%8%23%
2660
December1st to 10thNight
19%15%7%10%7%45%5%6%7%17%
2660
11th to 20thNight
15%17%7%10%7%45%45%6%20%
3288
21st to endNight
28%20%8%10%7%35%4449%
4884

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 10thDay
64%9%11%9%7%
2580
11th to 20thDay
73%6%10%7%3
2840
21st to endDay
75%7%7%7%3
3124
February1st to 10thDay
67%8%11%11%31
1710
11th to 20thDay
62%6%11%14%6%1
1672
21st to endDay
62%6%12%12%6%1
1513
March1st to 10thDay
56%6%14%16%7%1
2065
11th to 20thDay
54%7%11%16%10%2
2090
21st to endDay
55%6%10%16%11%2
2255
April1st to 10thDay
55%7%12%16%11%
2081
11th to 20thDay
49%6%11%20%12%1
2258
21st to endDay
53%6%11%17%11%2
2340
May1st to 10thDay
48%7%12%20%12%1
2340
11th to 20thDay
46%7%12%22%11%2
2383
21st to endDay
39%8%16%22%14%2
2725
June1st to 10thDay
41%8%13%21%14%2
2520
11th to 20thDay
38%8%15%23%15%1
2623
21st to endDay
39%8%15%23%15%
2700
July1st to 10thDay
33%8%16%24%17%3
2618
11th to 20thDay
38%10%16%25%11%1
2373
21st to endDay
39%10%15%21%13%2
2405
August1st to 10thDay
37%9%19%23%10%2
2314
11th to 20thDay
40%10%18%21%11%
2303
21st to endDay
40%8%14%25%11%1
2516
September1st to 10thDay
41%9%16%22%11%1
2160
11th to 20thDay
36%7%16%27%13%
1986
21st to endDay
44%9%14%24%8%1
1980
October1st to 10thDay
50%8%13%16%12%1
1805
11th to 20thDay
55%8%13%16%7%1
1800
21st to endDay
61%9%12%13%6%
1977
November1st to 10thDay
51%8%13%19%7%1
1636
11th to 20thDay
57%9%15%12%7%1
1520
21st to endDay
63%8%13%11%4
1520
December1st to 10thDay
69%9%10%8%4
1520
11th to 20thDay
68%10%10%9%3
1906
21st to endDay
79%7%7%6%1
2772
January1st to 10thNight
65%11%10%10%41
4365
11th to 20thNight
68%12%10%7%3
4120
21st to endNight
68%8%10%9%41
4532
February1st to 10thNight
62%8%11%14%4
2470
11th to 20thNight
57%7%12%15%8%1
2405
21st to endNight
58%7%13%15%7%
1937
March1st to 10thNight
50%7%14%19%9%2
2114
11th to 20thNight
50%7%12%19%11%2
2090
21st to endNight
50%5%8%20%14%3
2256
April1st to 10thNight
51%5%10%19%13%1
1878
11th to 20thNight
46%6%10%19%16%2
1667
21st to endNight
47%7%10%19%15%3
1620
May1st to 10thNight
44%7%10%21%15%3
1620
11th to 20thNight
41%6%13%24%13%4
1511
21st to endNight
31%7%15%26%17%4
1551
June1st to 10thNight
36%8%12%26%17%2
1440
11th to 20thNight
35%7%13%25%17%2
1330
21st to endNight
35%8%15%24%17%1
1260
July1st to 10thNight
24%7%13%27%25%4
1229
11th to 20thNight
30%6%16%29%17%2
1461
21st to endNight
31%9%15%26%16%3
1672
August1st to 10thNight
31%9%17%31%11%2
1600
11th to 20thNight
28%9%17%30%15%1
1598
21st to endNight
33%9%14%28%14%2
1820
September1st to 10thNight
36%8%14%26%15%2
1800
11th to 20thNight
30%7%13%31%18%1
1970
21st to endNight
41%9%11%26%13%
1980
October1st to 10thNight
44%7%11%23%15%1
2155
11th to 20thNight
48%8%14%22%8%1
2160
21st to endNight
56%7%11%17%9%1
2376
November1st to 10thNight
45%8%13%20%12%1
2439
11th to 20thNight
54%8%15%16%6%1
2660
21st to endNight
58%8%16%13%5%
2660
December1st to 10thNight
66%9%12%11%3
2660
11th to 20thNight
63%8%13%12%3
3288
21st to endNight
78%8%8%5%1
4884

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 10thDay
23%22%32%16%7%1
198
11th to 20thDay
23%22%39%12%41
270
21st to endDay
26%18%35%16%4
297
February1st to 10thDay
26%24%34%11%4
270
11th to 20thDay
23%26%37%13%1
270
21st to endDay
34%25%30%10%
225
March1st to 10thDay
24%17%35%18%6%
435
11th to 20thDay
23%17%34%21%41
460
21st to endDay
28%16%31%19%6%1
490
April1st to 10thDay
20%21%31%20%7%1
420
11th to 20thDay
26%17%26%18%10%2
412
21st to endDay
25%13%34%19%9%2
420
May1st to 10thDay
21%16%27%22%9%5%
423
11th to 20thDay
17%11%31%24%13%4
447
21st to endDay
13%7%28%28%15%8%
485
June1st to 10thDay
14%14%29%28%12%3
450
11th to 20thDay
13%10%28%30%16%4
553
21st to endDay
15%8%31%31%13%3
630
July1st to 10thDay
8%7%25%30%22%8%
613
11th to 20thDay
14%8%22%26%20%9%
444
21st to endDay
9%428%35%16%7%
488
August1st to 10thDay
9%6%21%29%22%13%
446
11th to 20thDay
10%6%20%27%23%13%
439
21st to endDay
14%7%24%24%21%10%
495
September1st to 10thDay
11%10%22%27%18%12%
450
11th to 20thDay
10%6%21%26%25%13%
450
21st to endDay
17%12%25%23%16%8%
450
October1st to 10thDay
22%13%25%23%11%7%
450
11th to 20thDay
22%19%33%18%8%1
450
21st to endDay
28%16%32%18%5%
492
November1st to 10thDay
24%21%32%14%8%2
252
11th to 20thDay
27%17%33%16%5%2
180
21st to endDay
27%19%34%17%3
180
December1st to 10thDay
28%25%32%9%6%
180
11th to 20thDay
28%28%29%12%31
180
21st to endDay
27%24%38%11%1
198
January1st to 10thNight
23%19%36%16%5%1
760
11th to 20thNight
27%18%33%20%2
760
21st to endNight
20%14%38%24%5%
836
February1st to 10thNight
23%18%36%21%2
760
11th to 20thNight
22%17%36%22%4
743
21st to endNight
23%19%35%20%3
628
March1st to 10thNight
18%15%38%24%6%
760
11th to 20thNight
20%17%35%21%6%
760
21st to endNight
21%14%32%25%8%1
821
April1st to 10thNight
23%15%32%25%4
720
11th to 20thNight
20%15%32%23%9%1
603
21st to endNight
16%11%34%30%8%
540
May1st to 10thNight
16%8%33%29%13%1
540
11th to 20thNight
16%5%32%35%11%1
449
21st to endNight
11%5%28%37%19%
389
June1st to 10thNight
12%5%32%39%12%1
360
11th to 20thNight
11%6%32%39%11%1
360
21st to endNight
11%5%28%41%15%
360
July1st to 10thNight
4324%47%21%1
350
11th to 20thNight
10%325%38%21%2
417
21st to endNight
10%320%46%19%1
591
August1st to 10thNight
7%321%42%25%2
537
11th to 20thNight
7%318%39%30%3
534
21st to endNight
11%324%34%25%2
632
September1st to 10thNight
12%7%21%35%22%4
720
11th to 20thNight
13%6%20%32%26%4
720
21st to endNight
17%9%22%29%19%5%
720
October1st to 10thNight
19%8%28%27%16%3
720
11th to 20thNight
21%12%31%28%8%1
720
21st to endNight
27%14%30%24%5%
792
November1st to 10thNight
20%14%29%27%10%2
740
11th to 20thNight
21%18%33%21%6%1
760
21st to endNight
25%15%35%20%5%
760
December1st to 10thNight
26%21%31%18%5%
760
11th to 20thNight
23%20%36%17%3
760
21st to endNight
30%17%34%17%2
836
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