Sault Ste. Marie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sault Ste. Marie clear sky chart from 2005-11-06 to 2024-11-06.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	14% 10% 4 8% 5% 5% 4 4 5% 7% 34%	101503
	Night	15% 12% 4 9% 5% 5% 4 4 5% 6% 31%	97670
Transparency	Day	28% 46% 7% 13% 6% 1	104980
	Night	30% 47% 7% 12% 5% 1	102281
Seeing	Day	19% 13% 29% 24% 12% 3	15583
	Night	21% 10% 27% 31% 11% 1	24965

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	12% 20% 7% 17% 7% 6% 4 3 5% 5% 15%	2400
	11th to 20th	Day	11% 14% 6% 13% 9% 7% 5% 5% 6% 6% 18%	2530
	21st to end	Day	10% 21% 11% 16% 8% 5% 5% 4 4 4 11%	2783
February	1st to 10th	Day	9% 14% 5% 14% 9% 6% 6% 5% 6% 6% 20%	1631
	11th to 20th	Day	11% 14% 5% 10% 8% 7% 6% 4 5% 6% 24%	1752
	21st to end	Day	10% 13% 6% 13% 7% 5% 4 4 5% 7% 26%	1570
March	1st to 10th	Day	11% 14% 5% 8% 4 4 4 3 5% 7% 35%	3118
	11th to 20th	Day	11% 15% 4 9% 5% 5% 5% 4 5% 7% 32%	3448
	21st to end	Day	16% 13% 8% 10% 6% 5% 5% 3 4 5% 25%	3868
April	1st to 10th	Day	17% 12% 4 8% 5% 5% 4 3 5% 6% 31%	2280
	11th to 20th	Day	20% 10% 3 7% 4 5% 4 3 5% 5% 35%	2423
	21st to end	Day	18% 10% 2 7% 4 4 4 4 6% 6% 34%	2470
May	1st to 10th	Day	17% 8% 3 7% 5% 5% 4 3 5% 7% 38%	4108
	11th to 20th	Day	12% 7% 3 6% 5% 4 4 3 5% 7% 43%	4239
	21st to end	Day	17% 6% 2 5% 3 4 4 3 6% 7% 43%	5147
June	1st to 10th	Day	15% 7% 2 5% 4 4 5% 4 8% 7% 40%	2850
	11th to 20th	Day	12% 6% 3 7% 5% 5% 4 5% 7% 8% 38%	2850
	21st to end	Day	15% 7% 3 6% 4 4 5% 3 5% 8% 41%	2850
July	1st to 10th	Day	16% 8% 2 6% 4 3 4 4 6% 8% 40%	4760
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 4 7% 9% 44%	4451
	21st to end	Day	11% 5% 1 5% 3 3 4 3 6% 9% 50%	4814
August	1st to 10th	Day	8% 5% 3 6% 5% 5% 5% 4 7% 8% 44%	4242
	11th to 20th	Day	14% 5% 2 6% 4 4 4 3 6% 7% 46%	4044
	21st to end	Day	15% 7% 3 6% 4 4 4 3 5% 6% 44%	4514
September	1st to 10th	Day	15% 6% 2 7% 4 5% 4 3 5% 7% 41%	2223
	11th to 20th	Day	15% 6% 3 6% 4 4 4 4 5% 9% 41%	2090
	21st to end	Day	17% 9% 3 7% 5% 5% 3 3 5% 8% 34%	2090
October	1st to 10th	Day	18% 8% 3 7% 4 5% 4 4 5% 7% 34%	2043
	11th to 20th	Day	22% 12% 4 10% 8% 6% 5% 4 4 6% 20%	1818
	21st to end	Day	25% 10% 3 10% 6% 6% 6% 4 5% 5% 20%	1881
November	1st to 10th	Day	22% 13% 3 10% 6% 5% 5% 3 4 6% 22%	1717
	11th to 20th	Day	15% 17% 4 10% 7% 6% 5% 3 7% 7% 19%	1608
	21st to end	Day	18% 19% 7% 12% 7% 5% 4 3 4 6% 15%	1459
December	1st to 10th	Day	14% 18% 5% 11% 7% 6% 7% 3 6% 5% 18%	1330
	11th to 20th	Day	17% 17% 6% 14% 6% 5% 5% 3 4 5% 18%	1671
	21st to end	Day	26% 23% 5% 10% 5% 3 4 2 3 4 15%	2431
January	1st to 10th	Night	15% 17% 7% 13% 5% 4 4 3 4 6% 21%	4552
	11th to 20th	Night	10% 16% 5% 13% 9% 8% 6% 4 5% 5% 20%	4440
	21st to end	Night	13% 17% 10% 16% 8% 6% 5% 3 4 5% 12%	4884
February	1st to 10th	Night	9% 16% 6% 13% 9% 7% 5% 5% 6% 6% 18%	2547
	11th to 20th	Night	12% 13% 5% 12% 8% 6% 6% 4 6% 5% 24%	2313
	21st to end	Night	10% 16% 5% 13% 7% 5% 4 4 6% 6% 23%	1884
March	1st to 10th	Night	15% 12% 3 7% 4 4 4 3 5% 7% 37%	3722
	11th to 20th	Night	9% 12% 5% 9% 4 4 4 4 6% 7% 36%	3511
	21st to end	Night	14% 9% 6% 9% 5% 5% 5% 4 5% 7% 31%	3791
April	1st to 10th	Night	18% 11% 3 9% 5% 4 4 4 6% 6% 30%	1900
	11th to 20th	Night	20% 8% 3 7% 4 3 4 3 5% 8% 36%	1706
	21st to end	Night	17% 9% 3 7% 5% 4 5% 4 5% 6% 36%	1710
May	1st to 10th	Night	18% 7% 3 7% 5% 5% 4 4 5% 6% 38%	2833
	11th to 20th	Night	13% 7% 3 9% 5% 5% 5% 3 6% 5% 37%	2646
	21st to end	Night	16% 9% 3 6% 3 3 4 3 5% 7% 40%	2437
June	1st to 10th	Night	12% 6% 2 6% 5% 4 5% 4 7% 9% 40%	1330
	11th to 20th	Night	14% 7% 2 5% 4 5% 4 4 5% 8% 41%	1330
	21st to end	Night	14% 7% 2 7% 4 4 5% 4 5% 8% 41%	1330
July	1st to 10th	Night	15% 5% 2 5% 4 4 4 5% 6% 8% 40%	2210
	11th to 20th	Night	8% 6% 2 6% 4 4 3 4 6% 7% 50%	2515
	21st to end	Night	12% 5% 2 4 4 3 4 3 6% 8% 48%	2750
August	1st to 10th	Night	10% 8% 3 7% 4 4 5% 4 7% 8% 40%	2689
	11th to 20th	Night	12% 5% 2 6% 3 4 4 3 6% 8% 46%	2785
	21st to end	Night	12% 5% 2 6% 4 3 4 3 4 6% 51%	3139
September	1st to 10th	Night	12% 6% 3 6% 4 5% 4 4 5% 6% 46%	1938
	11th to 20th	Night	15% 6% 2 6% 4 3 5% 3 6% 8% 44%	2090
	21st to end	Night	18% 8% 2 7% 5% 5% 4 4 5% 7% 36%	2090
October	1st to 10th	Night	19% 9% 2 6% 3 4 4 4 7% 6% 35%	2137
	11th to 20th	Night	22% 12% 3 8% 4 4 5% 4 5% 6% 27%	2361
	21st to end	Night	25% 12% 3 9% 5% 4 5% 4 5% 6% 23%	2717
November	1st to 10th	Night	20% 14% 4 7% 6% 4 5% 4 5% 6% 26%	2483
	11th to 20th	Night	18% 16% 5% 11% 7% 5% 5% 4 5% 6% 19%	2569
	21st to end	Night	18% 16% 5% 11% 5% 5% 5% 4 5% 6% 19%	2719
December	1st to 10th	Night	14% 18% 6% 12% 6% 5% 4 4 5% 6% 20%	2850
	11th to 20th	Night	18% 17% 5% 9% 5% 4 4 3 4 5% 26%	3526
	21st to end	Night	23% 24% 6% 11% 5% 4 3 2 3 4 15%	5236

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	48% 36% 8% 5% 2	2401
	11th to 20th	Day	42% 36% 9% 11% 1 1	2530
	21st to end	Day	50% 39% 6% 2 2	2783
February	1st to 10th	Day	21% 66% 5% 5% 2	1631
	11th to 20th	Day	22% 64% 4 5% 5%	1761
	21st to end	Day	21% 65% 4 6% 4	1570
March	1st to 10th	Day	31% 40% 11% 10% 7% 1	3120
	11th to 20th	Day	36% 39% 6% 12% 5% 1	3448
	21st to end	Day	42% 39% 4 7% 7% 1	3868
April	1st to 10th	Day	21% 65% 4 6% 4	2280
	11th to 20th	Day	20% 65% 2 8% 5% 1	2423
	21st to end	Day	17% 65% 4 8% 5% 1	2470
May	1st to 10th	Day	31% 39% 3 16% 10% 1	4120
	11th to 20th	Day	25% 38% 7% 20% 10%	4243
	21st to end	Day	27% 39% 6% 13% 12% 3	5147
June	1st to 10th	Day	15% 65% 3 10% 6% 1	2850
	11th to 20th	Day	17% 65% 4 8% 5% 1	2850
	21st to end	Day	15% 64% 5% 10% 6%	2850
July	1st to 10th	Day	31% 37% 9% 14% 8% 1	4686
	11th to 20th	Day	21% 39% 11% 23% 5%	4375
	21st to end	Day	18% 37% 7% 23% 14%	4662
August	1st to 10th	Day	21% 39% 8% 23% 8%	4227
	11th to 20th	Day	26% 38% 9% 20% 6%	4083
	21st to end	Day	27% 39% 10% 16% 7%	4513
September	1st to 10th	Day	18% 60% 6% 10% 5%	2223
	11th to 20th	Day	15% 60% 6% 15% 4	2090
	21st to end	Day	17% 61% 8% 10% 4	2090
October	1st to 10th	Day	20% 39% 10% 20% 11%	3394
	11th to 20th	Day	28% 38% 9% 23% 2	2995
	21st to end	Day	42% 39% 7% 9% 3	3081
November	1st to 10th	Day	29% 58% 4 7% 1	1717
	11th to 20th	Day	27% 61% 5% 5% 2	1608
	21st to end	Day	31% 60% 3 2 3	1459
December	1st to 10th	Day	31% 61% 3 4 2	1330
	11th to 20th	Day	39% 48% 5% 4 3 1	1671
	21st to end	Day	50% 36% 5% 5% 4	2431
January	1st to 10th	Night	44% 37% 6% 8% 6%	4552
	11th to 20th	Night	43% 36% 8% 9% 3	4440
	21st to end	Night	51% 39% 5% 3 2	4884
February	1st to 10th	Night	22% 66% 5% 5% 1	2547
	11th to 20th	Night	20% 64% 4 8% 3	2315
	21st to end	Night	22% 64% 4 4 5%	1884
March	1st to 10th	Night	30% 40% 11% 14% 5%	3733
	11th to 20th	Night	30% 39% 9% 16% 6% 1	3512
	21st to end	Night	36% 39% 6% 10% 8% 1	3791
April	1st to 10th	Night	22% 65% 2 7% 4	1900
	11th to 20th	Night	18% 65% 3 8% 5% 1	1706
	21st to end	Night	18% 65% 3 7% 5% 1	1710
May	1st to 10th	Night	32% 39% 4 16% 8% 1	2840
	11th to 20th	Night	30% 39% 4 20% 7%	2647
	21st to end	Night	31% 39% 7% 11% 8% 4	2438
June	1st to 10th	Night	15% 65% 4 8% 7% 1	1330
	11th to 20th	Night	18% 65% 3 7% 5% 1	1330
	21st to end	Night	15% 64% 3 11% 6% 1	1330
July	1st to 10th	Night	30% 38% 9% 15% 8%	2175
	11th to 20th	Night	20% 37% 11% 23% 8%	2468
	21st to end	Night	20% 37% 7% 19% 16% 1	2662
August	1st to 10th	Night	27% 39% 6% 19% 8%	2680
	11th to 20th	Night	25% 40% 8% 19% 7%	2812
	21st to end	Night	22% 38% 7% 24% 8%	3139
September	1st to 10th	Night	16% 61% 7% 10% 6%	1938
	11th to 20th	Night	14% 60% 7% 14% 4 1	2090
	21st to end	Night	19% 60% 7% 10% 4	2090
October	1st to 10th	Night	23% 40% 8% 22% 6%	3566
	11th to 20th	Night	23% 39% 11% 22% 5%	3923
	21st to end	Night	36% 42% 12% 7% 2	4467
November	1st to 10th	Night	29% 57% 5% 6% 2	2483
	11th to 20th	Night	26% 61% 5% 6% 2	2569
	21st to end	Night	29% 61% 5% 3 2	2719
December	1st to 10th	Night	28% 60% 6% 5% 1	2850
	11th to 20th	Night	30% 49% 8% 6% 5% 2	3525
	21st to end	Night	51% 36% 4 7% 2	5236

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	19% 15% 29% 24% 12% 1	234
	11th to 20th	Day	19% 11% 29% 30% 10% 1	270
	21st to end	Day	20% 11% 28% 31% 9% 1	297
February	1st to 10th	Day	19% 17% 34% 23% 6% 1	270
	11th to 20th	Day	17% 20% 37% 19% 5% 1	270
	21st to end	Day	17% 27% 35% 17% 4	225
March	1st to 10th	Day	19% 18% 34% 20% 9%	270
	11th to 20th	Day	19% 15% 30% 26% 8% 2	441
	21st to end	Day	24% 13% 28% 22% 12% 1	506
April	1st to 10th	Day	20% 17% 28% 27% 7% 1	460
	11th to 20th	Day	25% 18% 25% 19% 10% 3	452
	21st to end	Day	24% 15% 28% 20% 10% 4	460
May	1st to 10th	Day	21% 17% 27% 19% 12% 4	463
	11th to 20th	Day	19% 12% 31% 23% 11% 4	580
	21st to end	Day	17% 12% 30% 26% 11% 4	734
June	1st to 10th	Day	17% 13% 34% 23% 11% 2	680
	11th to 20th	Day	15% 15% 31% 27% 10% 2	680
	21st to end	Day	19% 12% 29% 26% 11% 3	680
July	1st to 10th	Day	10% 10% 35% 28% 13% 4	671
	11th to 20th	Day	13% 9% 29% 28% 15% 6%	668
	21st to end	Day	12% 9% 29% 29% 16% 5%	739
August	1st to 10th	Day	12% 8% 23% 31% 20% 5%	573
	11th to 20th	Day	15% 6% 16% 31% 22% 11%	479
	21st to end	Day	18% 9% 23% 25% 19% 6%	539
September	1st to 10th	Day	19% 9% 24% 24% 19% 6%	490
	11th to 20th	Day	15% 9% 24% 31% 18% 4	490
	21st to end	Day	21% 11% 22% 28% 14% 3	490
October	1st to 10th	Day	21% 18% 23% 22% 13% 2	490
	11th to 20th	Day	24% 16% 31% 24% 5%	408
	21st to end	Day	34% 18% 30% 15% 3 1	330
November	1st to 10th	Day	26% 21% 33% 15% 6% 1	285
	11th to 20th	Day	22% 20% 33% 18% 5% 1	221
	21st to end	Day	28% 17% 35% 15% 6%	180
December	1st to 10th	Day	26% 9% 33% 19% 11% 2	180
	11th to 20th	Day	24% 17% 37% 15% 6% 1	180
	21st to end	Day	33% 13% 31% 16% 8% 1	198
January	1st to 10th	Night	22% 13% 30% 29% 7%	950
	11th to 20th	Night	21% 11% 29% 27% 10% 1	950
	21st to end	Night	21% 10% 28% 31% 9% 1	1045
February	1st to 10th	Night	17% 12% 33% 31% 6% 1	837
	11th to 20th	Night	18% 12% 31% 30% 8% 1	743
	21st to end	Night	17% 14% 34% 30% 6%	628
March	1st to 10th	Night	17% 10% 34% 29% 10% 1	760
	11th to 20th	Night	17% 13% 32% 28% 9% 1	760
	21st to end	Night	18% 10% 31% 33% 7% 1	822
April	1st to 10th	Night	21% 10% 27% 35% 7% 1	570
	11th to 20th	Night	23% 9% 25% 33% 10% 1	563
	21st to end	Night	21% 9% 25% 32% 12% 1	570
May	1st to 10th	Night	18% 8% 24% 38% 11% 1	570
	11th to 20th	Night	20% 5% 26% 35% 14% 1	561
	21st to end	Night	14% 7% 27% 41% 10%	434
June	1st to 10th	Night	14% 5% 28% 42% 10%	380
	11th to 20th	Night	17% 5% 29% 36% 12%	380
	21st to end	Night	19% 4 24% 37% 15% 1	380
July	1st to 10th	Night	12% 4 22% 48% 13% 1	370
	11th to 20th	Night	13% 5% 17% 40% 23% 2	538
	21st to end	Night	15% 3 17% 41% 21% 2	624
August	1st to 10th	Night	15% 4 18% 38% 24% 1	567
	11th to 20th	Night	10% 4 17% 36% 31% 3	564
	21st to end	Night	16% 5% 17% 37% 23% 1	627
September	1st to 10th	Night	16% 5% 23% 32% 21% 3	608
	11th to 20th	Night	17% 6% 23% 33% 18% 3	760
	21st to end	Night	22% 8% 20% 33% 15% 3	760
October	1st to 10th	Night	24% 11% 24% 27% 14% 1	760
	11th to 20th	Night	28% 12% 24% 28% 7% 1	760
	21st to end	Night	31% 11% 25% 27% 5% 1	836
November	1st to 10th	Night	29% 12% 27% 24% 8% 1	764
	11th to 20th	Night	25% 14% 30% 23% 7%	760
	21st to end	Night	26% 14% 31% 25% 5%	819
December	1st to 10th	Night	24% 13% 32% 23% 7% 1	950
	11th to 20th	Night	26% 14% 32% 20% 6% 1	950
	21st to end	Night	31% 12% 28% 23% 7%	1045

Page generated at 2024-11-03 13:19:06. Version ac07

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