Lake St. Peter Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake St. Peter Provincial Park clear sky chart from 2005-11-06 to 2025-12-03.

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	16% 12% 4 9% 5% 5% 4 3 5% 6% 30%	127535
	Night	15% 13% 5% 10% 6% 5% 4 3 5% 6% 29%	123105
Transparency	Day	54% 4 10% 20% 10% 1	131076
	Night	55% 5% 10% 19% 10% 1	127650
Seeing	Day	24% 18% 31% 18% 7% 2	15767
	Night	22% 16% 31% 22% 8% 1	24931

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	11% 17% 6% 13% 7% 7% 6% 5% 5% 5% 18%	3597
	11th to 20th	Day	9% 19% 9% 19% 8% 6% 4 3 4 4 14%	3570
	21st to end	Day	13% 18% 10% 16% 7% 5% 3 2 3 4 19%	4438
February	1st to 10th	Day	11% 18% 6% 15% 9% 5% 5% 3 4 5% 19%	1800
	11th to 20th	Day	11% 15% 6% 14% 7% 5% 5% 3 4 5% 24%	1753
	21st to end	Day	16% 17% 5% 11% 7% 6% 5% 3 5% 5% 22%	1550
March	1st to 10th	Day	17% 17% 4 11% 6% 4 3 3 4 6% 25%	4788
	11th to 20th	Day	10% 14% 5% 11% 6% 5% 6% 4 6% 7% 26%	4980
	21st to end	Day	16% 15% 5% 9% 4 3 3 2 3 4 35%	5551
April	1st to 10th	Day	19% 14% 4 8% 6% 4 4 3 5% 6% 28%	2400
	11th to 20th	Day	21% 13% 4 6% 4 4 4 2 4 5% 34%	2399
	21st to end	Day	21% 12% 3 9% 4 4 3 2 4 5% 33%	2600
May	1st to 10th	Day	21% 9% 3 8% 5% 4 4 3 4 6% 32%	6202
	11th to 20th	Day	17% 10% 3 8% 5% 4 4 3 5% 6% 35%	6318
	21st to end	Day	20% 10% 3 7% 5% 5% 5% 3 4 6% 33%	6949
June	1st to 10th	Day	20% 10% 3 6% 5% 5% 4 3 5% 7% 30%	2800
	11th to 20th	Day	15% 7% 2 7% 5% 5% 5% 5% 6% 9% 35%	2800
	21st to end	Day	17% 8% 3 6% 5% 5% 5% 4 6% 8% 33%	2871
July	1st to 10th	Day	15% 6% 3 6% 5% 5% 5% 4 6% 9% 35%	6360
	11th to 20th	Day	12% 5% 2 6% 4 4 4 4 6% 7% 44%	6360
	21st to end	Day	8% 6% 2 6% 4 4 5% 4 6% 9% 45%	6926
August	1st to 10th	Day	15% 8% 3 8% 5% 6% 6% 4 6% 7% 31%	4239
	11th to 20th	Day	17% 7% 2 7% 5% 5% 6% 5% 7% 7% 33%	4174
	21st to end	Day	10% 6% 2 6% 5% 5% 6% 5% 6% 9% 39%	4425
September	1st to 10th	Day	16% 8% 2 6% 4 4 5% 4 6% 8% 38%	2400
	11th to 20th	Day	14% 7% 2 5% 4 4 4 4 5% 7% 44%	2390
	21st to end	Day	19% 8% 3 6% 5% 5% 4 4 6% 7% 34%	2093
October	1st to 10th	Day	19% 11% 3 8% 4 4 4 3 4 6% 34%	2000
	11th to 20th	Day	22% 15% 4 9% 5% 4 4 3 4 5% 24%	2000
	21st to end	Day	26% 15% 5% 9% 5% 4 3 3 4 5% 21%	2152
November	1st to 10th	Day	17% 14% 4 9% 4 5% 3 4 5% 6% 29%	1728
	11th to 20th	Day	15% 18% 6% 11% 6% 5% 3 4 5% 5% 22%	1680
	21st to end	Day	19% 24% 6% 10% 6% 4 3 3 3 6% 15%	1680
December	1st to 10th	Day	16% 25% 7% 14% 6% 5% 5% 3 5% 5% 11%	2616
	11th to 20th	Day	16% 23% 7% 14% 6% 4 3 3 3 4 20%	2986
	21st to end	Day	20% 22% 8% 13% 6% 3 2 2 3 4 18%	3960
January	1st to 10th	Night	13% 16% 7% 16% 8% 7% 5% 3 4 4 16%	6349
	11th to 20th	Night	8% 17% 6% 19% 11% 7% 6% 3 5% 5% 12%	6315
	21st to end	Night	12% 16% 8% 17% 7% 6% 5% 4 4 5% 16%	6518
February	1st to 10th	Night	11% 17% 6% 13% 8% 6% 6% 4 4 6% 20%	2600
	11th to 20th	Night	12% 15% 5% 12% 6% 6% 6% 3 4 5% 26%	2533
	21st to end	Night	11% 18% 5% 10% 7% 6% 4 4 5% 6% 24%	2079
March	1st to 10th	Night	16% 16% 5% 12% 5% 4 4 2 3 5% 28%	5050
	11th to 20th	Night	8% 14% 5% 10% 6% 6% 5% 5% 6% 8% 26%	4979
	21st to end	Night	16% 12% 5% 10% 5% 4 4 3 5% 6% 30%	5380
April	1st to 10th	Night	19% 13% 4 9% 5% 4 4 3 5% 5% 30%	2000
	11th to 20th	Night	18% 11% 4 6% 5% 3 3 3 5% 5% 37%	1967
	21st to end	Night	18% 11% 4 8% 5% 5% 5% 3 5% 5% 31%	1800
May	1st to 10th	Night	21% 8% 2 7% 4 4 5% 4 5% 6% 33%	3737
	11th to 20th	Night	16% 8% 3 6% 4 3 4 2 5% 8% 42%	3575
	21st to end	Night	18% 8% 2 7% 5% 4 5% 3 4 7% 37%	3926
June	1st to 10th	Night	16% 9% 2 7% 5% 4 5% 4 5% 9% 35%	1600
	11th to 20th	Night	12% 6% 3 6% 4 4 4 5% 6% 7% 43%	1600
	21st to end	Night	16% 7% 3 7% 5% 4 5% 4 5% 7% 36%	1469
July	1st to 10th	Night	13% 8% 2 7% 5% 4 6% 4 6% 7% 37%	3600
	11th to 20th	Night	13% 7% 2 5% 4 4 4 4 5% 7% 46%	3600
	21st to end	Night	8% 6% 2 5% 4 4 4 3 5% 7% 51%	3926
August	1st to 10th	Night	11% 5% 2 6% 4 3 5% 4 7% 8% 46%	2907
	11th to 20th	Night	14% 8% 2 6% 4 4 4 3 5% 7% 42%	2875
	21st to end	Night	13% 5% 2 5% 4 4 4 4 6% 9% 45%	3439
September	1st to 10th	Night	11% 5% 2 6% 4 3 5% 4 6% 8% 46%	2000
	11th to 20th	Night	12% 6% 2 6% 3 3 4 3 5% 7% 49%	2009
	21st to end	Night	17% 8% 3 6% 4 3 4 4 4 5% 41%	2306
October	1st to 10th	Night	18% 9% 3 5% 4 4 3 3 4 6% 39%	2400
	11th to 20th	Night	18% 14% 3 9% 5% 4 4 3 5% 6% 29%	2400
	21st to end	Night	22% 15% 4 8% 5% 5% 4 3 5% 5% 25%	2686
November	1st to 10th	Night	16% 14% 5% 8% 5% 5% 4 3 5% 6% 29%	2787
	11th to 20th	Night	16% 14% 5% 9% 6% 5% 5% 5% 5% 5% 25%	2940
	21st to end	Night	18% 18% 6% 12% 6% 5% 5% 3 4 5% 17%	2940
December	1st to 10th	Night	17% 21% 8% 13% 6% 6% 4 3 5% 5% 13%	4609
	11th to 20th	Night	16% 20% 8% 14% 5% 4 3 3 3 4 19%	5208
	21st to end	Night	22% 21% 7% 13% 7% 4 3 2 3 4 15%	6996

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	67% 4 8% 14% 7% 1	3598
	11th to 20th	Day	75% 2 6% 9% 7% 1	3600
	21st to end	Day	71% 2 5% 11% 9% 2	4438
February	1st to 10th	Day	67% 5% 6% 14% 6% 1	1800
	11th to 20th	Day	63% 4 9% 13% 9% 1	1762
	21st to end	Day	65% 3 8% 13% 11% 1	1550
March	1st to 10th	Day	61% 3 10% 9% 15% 2	4791
	11th to 20th	Day	57% 4 13% 16% 7% 2	4980
	21st to end	Day	54% 4 5% 18% 15% 3	5551
April	1st to 10th	Day	58% 4 6% 18% 11% 2	2400
	11th to 20th	Day	54% 4 6% 21% 14% 1	2399
	21st to end	Day	55% 4 7% 18% 13% 3	2600
May	1st to 10th	Day	53% 5% 7% 20% 10% 5%	6212
	11th to 20th	Day	49% 6% 8% 20% 16% 1	6322
	21st to end	Day	52% 5% 10% 19% 12% 2	6949
June	1st to 10th	Day	53% 5% 8% 21% 11% 1	2800
	11th to 20th	Day	44% 7% 10% 24% 13% 2	2800
	21st to end	Day	48% 7% 11% 20% 12% 1	2871
July	1st to 10th	Day	45% 3 14% 27% 10% 1	6290
	11th to 20th	Day	38% 4 12% 32% 14%	6285
	21st to end	Day	35% 4 14% 35% 11%	6728
August	1st to 10th	Day	51% 4 13% 23% 9%	4225
	11th to 20th	Day	48% 5% 13% 27% 7% 1	4213
	21st to end	Day	40% 6% 11% 32% 9%	4425
September	1st to 10th	Day	42% 7% 12% 27% 11% 1	2400
	11th to 20th	Day	39% 5% 11% 30% 14% 1	2390
	21st to end	Day	50% 6% 11% 23% 11%	2093
October	1st to 10th	Day	50% 4 10% 27% 9% 1	3260
	11th to 20th	Day	55% 3 10% 20% 11% 1	3240
	21st to end	Day	63% 3 10% 18% 5% 1	3454
November	1st to 10th	Day	55% 5% 13% 19% 7% 1	1728
	11th to 20th	Day	63% 5% 10% 13% 8% 1	1680
	21st to end	Day	71% 5% 7% 10% 6% 1	1680
December	1st to 10th	Day	77% 3 9% 8% 3	2616
	11th to 20th	Day	70% 5% 4 12% 8% 1	2986
	21st to end	Day	73% 2 5% 12% 8%	3960
January	1st to 10th	Night	71% 4 7% 12% 6%	6349
	11th to 20th	Night	73% 5% 6% 8% 6% 1	6360
	21st to end	Night	70% 4 5% 8% 11% 1	6518
February	1st to 10th	Night	65% 5% 8% 13% 8% 1	2600
	11th to 20th	Night	60% 5% 8% 18% 9% 1	2535
	21st to end	Night	60% 5% 7% 19% 9% 1	2079
March	1st to 10th	Night	60% 3 7% 12% 13% 5%	5060
	11th to 20th	Night	54% 5% 15% 17% 8% 1	4980
	21st to end	Night	54% 5% 7% 19% 13% 2	5380
April	1st to 10th	Night	57% 3 8% 18% 12% 2	2000
	11th to 20th	Night	50% 4 7% 23% 15% 1	1967
	21st to end	Night	55% 5% 7% 17% 14% 2	1800
May	1st to 10th	Night	51% 5% 9% 20% 11% 4	3743
	11th to 20th	Night	40% 8% 13% 22% 15% 2	3576
	21st to end	Night	47% 5% 12% 22% 13% 1	3927
June	1st to 10th	Night	46% 6% 11% 22% 14% 1	1600
	11th to 20th	Night	37% 7% 11% 28% 15% 1	1600
	21st to end	Night	46% 6% 14% 20% 13% 1	1469
July	1st to 10th	Night	45% 4 16% 21% 14% 1	3560
	11th to 20th	Night	38% 4 12% 34% 13%	3552
	21st to end	Night	33% 4 11% 37% 14%	3809
August	1st to 10th	Night	36% 4 16% 28% 14% 2	2897
	11th to 20th	Night	40% 5% 17% 28% 10% 1	2902
	21st to end	Night	37% 5% 13% 33% 11% 2	3439
September	1st to 10th	Night	34% 8% 15% 30% 12% 1	2000
	11th to 20th	Night	35% 5% 13% 34% 12% 1	2009
	21st to end	Night	45% 5% 10% 26% 12%	2306
October	1st to 10th	Night	40% 3 10% 30% 17%	3920
	11th to 20th	Night	51% 3 13% 21% 12% 1	3899
	21st to end	Night	55% 4 16% 18% 7%	4334
November	1st to 10th	Night	54% 6% 11% 20% 8%	2787
	11th to 20th	Night	59% 6% 10% 16% 7% 1	2940
	21st to end	Night	69% 6% 8% 12% 4	2940
December	1st to 10th	Night	74% 4 11% 9% 2	4609
	11th to 20th	Night	70% 3 5% 11% 9% 1	5208
	21st to end	Night	75% 3 3 10% 8%	6996

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	25% 25% 36% 13% 2 1	200
	11th to 20th	Day	30% 19% 36% 12% 4 1	200
	21st to end	Day	26% 22% 33% 15% 4	323
February	1st to 10th	Day	30% 29% 32% 6% 2	300
	11th to 20th	Day	27% 33% 32% 7%	300
	21st to end	Day	32% 24% 36% 8% 1	314
March	1st to 10th	Day	28% 22% 36% 13% 2	500
	11th to 20th	Day	29% 20% 34% 13% 3 1	500
	21st to end	Day	33% 21% 27% 13% 5% 1	550
April	1st to 10th	Day	29% 24% 30% 11% 5% 1	500
	11th to 20th	Day	38% 21% 21% 12% 7% 2	492
	21st to end	Day	31% 18% 32% 12% 5% 1	500
May	1st to 10th	Day	26% 18% 31% 16% 6% 2	503
	11th to 20th	Day	21% 19% 32% 19% 7% 2	527
	21st to end	Day	21% 19% 30% 20% 7% 2	573
June	1st to 10th	Day	25% 16% 35% 19% 5%	530
	11th to 20th	Day	17% 16% 35% 20% 9% 2	530
	21st to end	Day	21% 15% 34% 20% 8% 1	601
July	1st to 10th	Day	14% 10% 35% 30% 9% 2	525
	11th to 20th	Day	16% 12% 35% 23% 11% 3	524
	21st to end	Day	13% 13% 36% 25% 10% 2	576
August	1st to 10th	Day	15% 9% 34% 26% 12% 4	526
	11th to 20th	Day	17% 8% 28% 29% 14% 4	519
	21st to end	Day	17% 11% 32% 24% 12% 4	583
September	1st to 10th	Day	19% 13% 31% 21% 11% 5%	530
	11th to 20th	Day	15% 11% 24% 22% 18% 10%	530
	21st to end	Day	22% 14% 26% 21% 12% 5%	530
October	1st to 10th	Day	24% 19% 24% 19% 11% 3	530
	11th to 20th	Day	28% 25% 28% 14% 4 1	530
	21st to end	Day	35% 18% 29% 14% 3	555
November	1st to 10th	Day	31% 20% 29% 14% 5% 1	302
	11th to 20th	Day	30% 22% 32% 11% 4	220
	21st to end	Day	32% 24% 33% 9% 2	220
December	1st to 10th	Day	32% 19% 33% 13% 2	204
	11th to 20th	Day	35% 26% 26% 11% 2 1	200
	21st to end	Day	33% 25% 25% 12% 4 2	220
January	1st to 10th	Night	26% 21% 35% 15% 3 1	800
	11th to 20th	Night	27% 20% 32% 16% 5% 1	800
	21st to end	Night	19% 19% 34% 22% 6% 1	880
February	1st to 10th	Night	22% 23% 37% 17% 2	800
	11th to 20th	Night	20% 21% 41% 14% 3	783
	21st to end	Night	23% 24% 31% 18% 3	660
March	1st to 10th	Night	23% 24% 33% 17% 3	800
	11th to 20th	Night	21% 21% 36% 18% 4 1	800
	21st to end	Night	20% 19% 33% 21% 6%	880
April	1st to 10th	Night	28% 18% 32% 18% 5%	800
	11th to 20th	Night	25% 21% 26% 19% 8%	783
	21st to end	Night	25% 15% 29% 22% 10% 1	600
May	1st to 10th	Night	23% 11% 27% 28% 10% 1	465
	11th to 20th	Night	20% 11% 34% 29% 6%	394
	21st to end	Night	17% 11% 32% 29% 10%	433
June	1st to 10th	Night	19% 9% 35% 30% 7% 1	400
	11th to 20th	Night	18% 11% 27% 34% 11%	400
	21st to end	Night	20% 11% 27% 31% 12%	400
July	1st to 10th	Night	10% 8% 33% 34% 15% 1	390
	11th to 20th	Night	14% 7% 30% 34% 15% 1	388
	21st to end	Night	10% 6% 34% 38% 11% 1	438
August	1st to 10th	Night	12% 5% 23% 38% 20% 1	589
	11th to 20th	Night	11% 5% 22% 38% 22% 2	594
	21st to end	Night	14% 8% 28% 31% 17% 2	785
September	1st to 10th	Night	14% 9% 29% 30% 17% 2	800
	11th to 20th	Night	18% 7% 23% 29% 20% 4	800
	21st to end	Night	22% 11% 22% 27% 16% 2	800
October	1st to 10th	Night	24% 13% 28% 22% 11% 2	800
	11th to 20th	Night	25% 17% 31% 19% 7% 1	800
	21st to end	Night	31% 16% 26% 21% 5%	880
November	1st to 10th	Night	28% 16% 29% 21% 5%	820
	11th to 20th	Night	25% 20% 32% 15% 7% 1	840
	21st to end	Night	31% 18% 29% 18% 4	840
December	1st to 10th	Night	29% 19% 34% 13% 4	809
	11th to 20th	Night	27% 22% 33% 16% 3 1	800
	21st to end	Night	33% 19% 30% 15% 3	880

Page generated at 2025-11-30 01:00:57. Version ac07

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