Fenelon Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fenelon Falls clear sky chart from 2005-11-06 to 2025-08-05.

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	15% 11% 4 9% 5% 4 5% 4 5% 7% 32%	126081
	Night	15% 12% 4 10% 5% 5% 4 3 5% 6% 30%	121867
Transparency	Day	50% 6% 12% 21% 11% 1	129664
	Night	52% 6% 11% 19% 11% 1	126370
Seeing	Day	22% 15% 31% 19% 9% 3	15315
	Night	21% 15% 30% 23% 10% 1	24595

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	13% 13% 6% 13% 6% 5% 5% 4 5% 5% 25%	3597
	11th to 20th	Day	9% 18% 7% 18% 8% 8% 6% 3 4 4 14%	3725
	21st to end	Day	13% 19% 7% 14% 6% 6% 4 4 4 5% 18%	4466
February	1st to 10th	Day	14% 16% 5% 15% 9% 4 5% 4 3 4 21%	1800
	11th to 20th	Day	13% 16% 6% 13% 6% 5% 5% 2 4 4 26%	1753
	21st to end	Day	17% 15% 6% 11% 6% 5% 5% 3 4 5% 23%	1528
March	1st to 10th	Day	19% 12% 5% 10% 6% 3 4 3 4 5% 28%	4903
	11th to 20th	Day	11% 13% 5% 10% 5% 6% 5% 5% 6% 6% 27%	4980
	21st to end	Day	19% 13% 4 9% 4 3 4 2 3 5% 35%	5465
April	1st to 10th	Day	19% 12% 4 8% 6% 4 5% 3 5% 5% 30%	2400
	11th to 20th	Day	20% 11% 2 6% 5% 4 3 3 4 5% 36%	2423
	21st to end	Day	20% 10% 3 7% 5% 4 4 3 4 6% 34%	2600
May	1st to 10th	Day	18% 9% 3 7% 5% 5% 5% 3 6% 7% 33%	6026
	11th to 20th	Day	16% 11% 3 7% 5% 4 4 3 4 7% 35%	6318
	21st to end	Day	19% 9% 3 7% 4 4 4 3 5% 7% 35%	6949
June	1st to 10th	Day	17% 8% 3 7% 5% 4 5% 4 6% 7% 35%	2800
	11th to 20th	Day	13% 6% 3 6% 4 5% 4 4 7% 9% 37%	2800
	21st to end	Day	17% 7% 2 6% 5% 4 5% 3 6% 8% 37%	2800
July	1st to 10th	Day	11% 6% 3 7% 4 4 5% 5% 6% 10% 39%	6360
	11th to 20th	Day	10% 6% 2 6% 4 4 5% 3 6% 8% 46%	6360
	21st to end	Day	7% 5% 2 6% 4 4 5% 5% 7% 9% 47%	6709
August	1st to 10th	Day	15% 8% 3 6% 4 5% 4 4 6% 9% 37%	4156
	11th to 20th	Day	14% 7% 2 7% 5% 5% 5% 4 7% 10% 35%	4044
	21st to end	Day	8% 6% 2 6% 5% 4 5% 4 7% 9% 43%	4321
September	1st to 10th	Day	13% 7% 2 6% 5% 5% 5% 4 6% 7% 40%	2280
	11th to 20th	Day	12% 5% 1 6% 4 5% 4 3 6% 8% 46%	2219
	21st to end	Day	16% 6% 3 7% 5% 5% 5% 4 5% 6% 38%	2019
October	1st to 10th	Day	18% 10% 3 8% 5% 5% 4 3 5% 6% 33%	1900
	11th to 20th	Day	23% 10% 4 9% 5% 4 4 4 5% 6% 26%	1900
	21st to end	Day	25% 13% 4 8% 4 4 4 3 6% 6% 23%	2090
November	1st to 10th	Day	16% 11% 4 9% 5% 5% 4 4 5% 7% 31%	1644
	11th to 20th	Day	17% 12% 4 11% 6% 5% 5% 4 7% 8% 23%	1600
	21st to end	Day	20% 18% 4 10% 6% 4 5% 4 4 6% 18%	1600
December	1st to 10th	Day	17% 24% 6% 13% 6% 4 4 3 4 6% 13%	2600
	11th to 20th	Day	17% 19% 6% 12% 6% 4 4 3 4 5% 20%	2986
	21st to end	Day	23% 18% 5% 13% 5% 4 4 2 3 4 18%	3960
January	1st to 10th	Night	14% 17% 7% 13% 7% 6% 4 4 5% 5% 18%	6349
	11th to 20th	Night	11% 14% 8% 18% 9% 6% 6% 4 5% 5% 15%	6159
	21st to end	Night	13% 16% 8% 14% 6% 5% 5% 3 5% 5% 21%	6490
February	1st to 10th	Night	13% 16% 5% 12% 9% 7% 5% 4 5% 5% 20%	2600
	11th to 20th	Night	13% 15% 5% 11% 6% 5% 5% 4 6% 5% 25%	2533
	21st to end	Night	14% 14% 5% 11% 6% 5% 5% 3 5% 6% 26%	2101
March	1st to 10th	Night	16% 11% 4 11% 5% 5% 4 3 5% 6% 28%	4922
	11th to 20th	Night	9% 12% 5% 9% 6% 5% 6% 4 6% 7% 30%	4979
	21st to end	Night	20% 9% 4 8% 4 4 4 3 5% 6% 33%	5467
April	1st to 10th	Night	19% 13% 4 8% 5% 4 4 3 5% 6% 29%	2000
	11th to 20th	Night	17% 9% 3 7% 5% 3 3 3 6% 7% 36%	1943
	21st to end	Night	16% 11% 3 8% 5% 4 3 4 6% 6% 32%	1800
May	1st to 10th	Night	22% 9% 3 7% 5% 4 4 3 5% 6% 33%	3899
	11th to 20th	Night	12% 8% 3 6% 4 5% 4 3 5% 7% 42%	3575
	21st to end	Night	18% 8% 3 7% 4 4 4 3 5% 6% 39%	3926
June	1st to 10th	Night	15% 6% 2 6% 5% 4 5% 4 6% 8% 38%	1600
	11th to 20th	Night	11% 6% 2 5% 5% 5% 4 4 6% 9% 43%	1600
	21st to end	Night	13% 9% 2 7% 5% 5% 4 3 6% 9% 38%	1517
July	1st to 10th	Night	10% 6% 2 6% 5% 5% 5% 4 6% 8% 42%	3600
	11th to 20th	Night	11% 6% 2 4 3 3 4 3 5% 8% 49%	3600
	21st to end	Night	9% 6% 2 4 3 4 4 3 5% 8% 51%	4140
August	1st to 10th	Night	11% 5% 2 6% 5% 4 4 4 5% 8% 47%	2861
	11th to 20th	Night	14% 6% 2 5% 4 3 4 4 5% 6% 46%	2785
	21st to end	Night	11% 6% 2 5% 4 4 4 3 6% 7% 46%	3302
September	1st to 10th	Night	11% 6% 2 6% 4 4 5% 4 6% 8% 44%	1900
	11th to 20th	Night	12% 5% 2 5% 4 3 2 4 4 7% 51%	1957
	21st to end	Night	16% 8% 3 6% 4 4 4 3 5% 7% 40%	2160
October	1st to 10th	Night	17% 8% 3 8% 5% 5% 4 3 6% 6% 35%	2280
	11th to 20th	Night	20% 11% 3 9% 5% 4 5% 4 5% 5% 29%	2280
	21st to end	Night	23% 13% 2 8% 5% 5% 5% 3 4 6% 25%	2508
November	1st to 10th	Night	19% 12% 3 7% 5% 4 4 3 5% 6% 33%	2650
	11th to 20th	Night	16% 14% 4 9% 5% 5% 4 4 5% 6% 26%	2800
	21st to end	Night	21% 14% 4 11% 6% 6% 5% 5% 5% 6% 19%	2800
December	1st to 10th	Night	17% 19% 7% 14% 7% 5% 4 4 5% 5% 14%	4580
	11th to 20th	Night	16% 17% 7% 15% 7% 5% 5% 3 4 4 15%	5208
	21st to end	Night	23% 19% 6% 15% 5% 4 3 3 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	57% 6% 11% 16% 9%	3598
	11th to 20th	Day	72% 6% 8% 9% 6%	3756
	21st to end	Day	68% 5% 8% 9% 8% 1	4466
February	1st to 10th	Day	67% 5% 8% 15% 4 1	1800
	11th to 20th	Day	62% 5% 9% 14% 9% 1	1762
	21st to end	Day	63% 5% 9% 15% 8% 1	1528
March	1st to 10th	Day	57% 5% 12% 11% 14% 1	4906
	11th to 20th	Day	54% 7% 13% 17% 7% 2	4980
	21st to end	Day	52% 5% 7% 20% 16% 2	5465
April	1st to 10th	Day	56% 4 8% 19% 11% 1	2400
	11th to 20th	Day	50% 5% 8% 22% 15% 1	2423
	21st to end	Day	52% 5% 10% 18% 13% 3	2600
May	1st to 10th	Day	50% 5% 11% 20% 10% 4	6035
	11th to 20th	Day	48% 6% 10% 16% 19% 1	6322
	21st to end	Day	48% 5% 11% 21% 12% 2	6949
June	1st to 10th	Day	47% 7% 10% 21% 15%	2800
	11th to 20th	Day	41% 6% 13% 25% 14% 1	2800
	21st to end	Day	43% 8% 14% 22% 12% 1	2800
July	1st to 10th	Day	38% 6% 15% 27% 13% 1	6290
	11th to 20th	Day	34% 6% 13% 30% 16% 1	6285
	21st to end	Day	32% 7% 13% 35% 13%	6516
August	1st to 10th	Day	43% 6% 14% 24% 10% 1	4143
	11th to 20th	Day	42% 7% 15% 26% 9%	4083
	21st to end	Day	36% 7% 13% 34% 11% 1	4321
September	1st to 10th	Day	41% 7% 14% 27% 10% 1	2280
	11th to 20th	Day	36% 6% 14% 30% 13% 1	2219
	21st to end	Day	46% 6% 13% 25% 10%	2019
October	1st to 10th	Day	43% 5% 13% 28% 10% 1	3160
	11th to 20th	Day	48% 6% 14% 21% 11% 1	3140
	21st to end	Day	54% 6% 14% 18% 7%	3428
November	1st to 10th	Day	50% 7% 15% 19% 8% 1	1644
	11th to 20th	Day	57% 7% 12% 14% 8% 2	1600
	21st to end	Day	65% 7% 11% 13% 4	1600
December	1st to 10th	Day	72% 5% 12% 8% 3	2600
	11th to 20th	Day	66% 7% 9% 13% 5%	2986
	21st to end	Day	70% 5% 6% 11% 7%	3960
January	1st to 10th	Night	64% 6% 9% 13% 8%	6349
	11th to 20th	Night	68% 8% 9% 9% 5% 1	6203
	21st to end	Night	64% 5% 10% 9% 10% 1	6490
February	1st to 10th	Night	64% 6% 9% 16% 5% 1	2600
	11th to 20th	Night	59% 6% 10% 18% 8%	2535
	21st to end	Night	57% 6% 10% 19% 8% 1	2101
March	1st to 10th	Night	56% 5% 9% 15% 11% 4	4932
	11th to 20th	Night	49% 7% 17% 18% 8% 1	4980
	21st to end	Night	48% 7% 9% 20% 14% 2	5467
April	1st to 10th	Night	55% 5% 8% 19% 12% 1	2000
	11th to 20th	Night	47% 5% 9% 22% 15% 2	1943
	21st to end	Night	49% 6% 10% 17% 15% 2	1800
May	1st to 10th	Night	51% 5% 11% 14% 13% 4	3906
	11th to 20th	Night	41% 6% 14% 21% 17% 2	3576
	21st to end	Night	45% 6% 11% 24% 13% 1	3927
June	1st to 10th	Night	42% 7% 11% 24% 15% 2	1600
	11th to 20th	Night	37% 6% 12% 24% 20% 2	1600
	21st to end	Night	43% 7% 14% 21% 14% 2	1517
July	1st to 10th	Night	38% 6% 15% 23% 16% 1	3560
	11th to 20th	Night	33% 6% 13% 31% 17%	3552
	21st to end	Night	31% 6% 11% 36% 15% 1	4018
August	1st to 10th	Night	35% 5% 16% 25% 17% 1	2850
	11th to 20th	Night	36% 7% 17% 26% 13% 1	2812
	21st to end	Night	34% 7% 12% 34% 12% 1	3302
September	1st to 10th	Night	36% 7% 16% 27% 13% 1	1900
	11th to 20th	Night	32% 6% 13% 33% 15% 1	1957
	21st to end	Night	43% 6% 11% 29% 11%	2160
October	1st to 10th	Night	36% 6% 11% 27% 19% 1	3800
	11th to 20th	Night	46% 7% 15% 24% 8%	3779
	21st to end	Night	49% 8% 13% 22% 7%	4120
November	1st to 10th	Night	50% 7% 12% 21% 10%	2650
	11th to 20th	Night	55% 8% 12% 16% 7% 2	2800
	21st to end	Night	62% 8% 14% 12% 4	2800
December	1st to 10th	Night	69% 7% 12% 9% 3	4580
	11th to 20th	Night	70% 6% 10% 10% 4	5208
	21st to end	Night	74% 4 7% 9% 6%	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	21% 23% 37% 13% 7% 1	200
	11th to 20th	Day	24% 21% 35% 14% 5% 1	233
	21st to end	Day	23% 20% 37% 14% 5%	330
February	1st to 10th	Day	32% 23% 30% 11% 4	300
	11th to 20th	Day	26% 28% 36% 9% 1	300
	21st to end	Day	38% 18% 33% 11%	292
March	1st to 10th	Day	24% 18% 37% 17% 3	500
	11th to 20th	Day	27% 18% 34% 16% 4 1	500
	21st to end	Day	32% 16% 32% 14% 5% 1	550
April	1st to 10th	Day	27% 22% 30% 14% 6% 1	500
	11th to 20th	Day	33% 17% 27% 13% 7% 3	492
	21st to end	Day	29% 16% 34% 13% 7% 2	500
May	1st to 10th	Day	24% 13% 31% 19% 8% 5%	503
	11th to 20th	Day	19% 14% 35% 18% 11% 4	527
	21st to end	Day	18% 12% 33% 20% 11% 6%	573
June	1st to 10th	Day	21% 12% 35% 23% 9% 1	530
	11th to 20th	Day	17% 12% 27% 27% 12% 5%	530
	21st to end	Day	21% 12% 32% 24% 10% 3	530
July	1st to 10th	Day	11% 9% 29% 32% 15% 5%	525
	11th to 20th	Day	14% 9% 28% 28% 15% 6%	524
	21st to end	Day	8% 11% 35% 30% 12% 5%	576
August	1st to 10th	Day	15% 6% 27% 27% 17% 7%	502
	11th to 20th	Day	12% 9% 23% 28% 19% 8%	479
	21st to end	Day	12% 9% 32% 25% 16% 7%	539
September	1st to 10th	Day	14% 11% 29% 24% 16% 6%	490
	11th to 20th	Day	12% 8% 26% 21% 21% 12%	490
	21st to end	Day	19% 13% 28% 23% 13% 5%	490
October	1st to 10th	Day	23% 14% 29% 15% 14% 5%	490
	11th to 20th	Day	25% 19% 32% 16% 6% 2	490
	21st to end	Day	32% 20% 30% 13% 5%	539
November	1st to 10th	Day	29% 17% 31% 17% 6%	271
	11th to 20th	Day	28% 22% 35% 11% 3 2	200
	21st to end	Day	29% 18% 42% 10% 2	200
December	1st to 10th	Day	30% 20% 33% 13% 5% 1	200
	11th to 20th	Day	31% 25% 29% 13% 3 1	200
	21st to end	Day	31% 18% 35% 12% 3 1	220
January	1st to 10th	Night	25% 23% 31% 16% 6% 1	800
	11th to 20th	Night	27% 18% 31% 18% 5% 1	800
	21st to end	Night	19% 17% 34% 23% 5% 1	880
February	1st to 10th	Night	22% 22% 36% 18% 2	800
	11th to 20th	Night	24% 20% 36% 17% 3	783
	21st to end	Night	23% 21% 33% 18% 3	660
March	1st to 10th	Night	23% 19% 35% 20% 3	800
	11th to 20th	Night	21% 22% 34% 18% 5% 1	800
	21st to end	Night	22% 14% 35% 22% 7%	880
April	1st to 10th	Night	26% 19% 31% 19% 5%	800
	11th to 20th	Night	24% 15% 32% 20% 8% 1	759
	21st to end	Night	20% 14% 34% 23% 9% 1	600
May	1st to 10th	Night	21% 8% 29% 28% 12% 2	537
	11th to 20th	Night	16% 10% 33% 32% 8%	394
	21st to end	Night	13% 9% 32% 33% 13%	433
June	1st to 10th	Night	16% 9% 32% 34% 8% 1	400
	11th to 20th	Night	13% 9% 28% 36% 13% 1	400
	21st to end	Night	13% 9% 27% 36% 14% 1	400
July	1st to 10th	Night	8% 7% 25% 42% 18% 1	390
	11th to 20th	Night	10% 7% 27% 35% 20% 1	388
	21st to end	Night	10% 5% 28% 39% 18% 1	525
August	1st to 10th	Night	11% 3 23% 34% 27% 2	579
	11th to 20th	Night	9% 6% 21% 34% 26% 4	564
	21st to end	Night	12% 5% 29% 30% 22% 2	727
September	1st to 10th	Night	12% 7% 30% 28% 19% 4	760
	11th to 20th	Night	13% 6% 25% 29% 23% 5%	760
	21st to end	Night	20% 10% 21% 31% 15% 4	760
October	1st to 10th	Night	19% 12% 28% 24% 14% 2	760
	11th to 20th	Night	25% 16% 31% 18% 8% 1	760
	21st to end	Night	29% 19% 29% 19% 5%	836
November	1st to 10th	Night	25% 16% 29% 21% 9% 1	780
	11th to 20th	Night	23% 20% 33% 18% 5% 1	800
	21st to end	Night	28% 20% 29% 19% 4	800
December	1st to 10th	Night	29% 24% 30% 14% 4	800
	11th to 20th	Night	25% 22% 33% 16% 3 1	800
	21st to end	Night	31% 20% 30% 17% 2	880

Page generated at 2025-08-02 01:32:26. Version ac07

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