Innisfil
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Innisfil clear sky chart from 2005-11-06 to 2026-03-03.

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	14% 10% 4 9% 6% 5% 5% 4 6% 7% 32%	131949
	Night	14% 10% 4 10% 6% 5% 5% 4 6% 7% 30%	129164
Transparency	Day	51% 4 12% 21% 11% 1	135540
	Night	53% 4 12% 20% 10% 1	133661
Seeing	Day	17% 8% 27% 26% 16% 6%	16392
	Night	19% 8% 29% 30% 13% 2	25469

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% 5% 14% 7% 6% 5% 4 5% 7% 22%	4661
	11th to 20th	Day	7% 16% 8% 19% 10% 9% 6% 4 6% 5% 11%	5024
	21st to end	Day	10% 14% 5% 14% 8% 8% 6% 5% 6% 7% 16%	5780
February	1st to 10th	Day	12% 15% 6% 12% 8% 8% 7% 5% 5% 5% 19%	1890
	11th to 20th	Day	12% 12% 6% 13% 9% 6% 5% 5% 5% 6% 22%	1843
	21st to end	Day	14% 14% 5% 11% 8% 6% 4 5% 6% 6% 21%	1603
March	1st to 10th	Day	17% 11% 4 9% 6% 5% 5% 4 4 6% 30%	4954
	11th to 20th	Day	10% 11% 4 10% 6% 6% 6% 4 6% 8% 28%	4980
	21st to end	Day	17% 10% 3 11% 5% 5% 5% 4 4 5% 32%	5465
April	1st to 10th	Day	17% 12% 4 9% 6% 4 5% 4 5% 5% 30%	2363
	11th to 20th	Day	19% 10% 2 6% 4 4 4 3 5% 7% 36%	2469
	21st to end	Day	19% 8% 3 7% 6% 5% 3 3 5% 6% 35%	2600
May	1st to 10th	Day	16% 8% 3 8% 5% 4 4 4 5% 7% 37%	5888
	11th to 20th	Day	13% 9% 3 8% 5% 5% 4 3 5% 7% 37%	6318
	21st to end	Day	18% 7% 2 7% 4 4 4 3 5% 7% 39%	6949
June	1st to 10th	Day	16% 7% 3 7% 4 4 5% 4 6% 7% 38%	2800
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 7% 9% 41%	2889
	21st to end	Day	15% 6% 2 6% 5% 5% 5% 4 6% 8% 40%	3000
July	1st to 10th	Day	11% 6% 2 7% 6% 5% 5% 5% 6% 8% 39%	6709
	11th to 20th	Day	8% 5% 2 5% 5% 5% 5% 4 6% 8% 47%	6360
	21st to end	Day	7% 4 2 5% 4 5% 4 4 6% 9% 49%	6543
August	1st to 10th	Day	13% 7% 3 6% 5% 4 5% 4 6% 7% 39%	4234
	11th to 20th	Day	12% 7% 3 7% 4 4 5% 4 7% 10% 37%	4174
	21st to end	Day	10% 5% 2 6% 4 4 5% 4 6% 9% 44%	4516
September	1st to 10th	Day	13% 6% 3 6% 5% 5% 5% 3 6% 7% 42%	2400
	11th to 20th	Day	12% 6% 2 6% 4 4 4 4 5% 8% 45%	2280
	21st to end	Day	15% 6% 2 8% 5% 6% 5% 4 6% 7% 36%	2160
October	1st to 10th	Day	18% 7% 3 7% 5% 5% 5% 4 5% 6% 35%	2000
	11th to 20th	Day	19% 10% 4 9% 6% 4 5% 4 6% 6% 27%	2000
	21st to end	Day	25% 12% 4 10% 5% 5% 4 4 5% 6% 21%	2200
November	1st to 10th	Day	15% 13% 4 9% 5% 5% 4 5% 6% 7% 28%	1743
	11th to 20th	Day	13% 17% 4 10% 7% 6% 5% 5% 5% 6% 21%	1680
	21st to end	Day	17% 18% 5% 11% 7% 7% 6% 3 5% 6% 16%	1680
December	1st to 10th	Day	16% 21% 7% 17% 8% 5% 5% 4 4 4 9%	2680
	11th to 20th	Day	15% 18% 5% 11% 6% 6% 6% 4 5% 5% 19%	3066
	21st to end	Day	23% 16% 7% 15% 6% 5% 5% 4 4 4 12%	4048
January	1st to 10th	Night	13% 15% 7% 16% 7% 5% 5% 4 5% 6% 18%	8234
	11th to 20th	Night	10% 13% 6% 17% 11% 8% 7% 5% 5% 5% 13%	7843
	21st to end	Night	10% 12% 5% 12% 9% 7% 7% 5% 7% 7% 18%	8401
February	1st to 10th	Night	11% 16% 5% 13% 8% 7% 5% 5% 6% 5% 21%	2730
	11th to 20th	Night	13% 14% 5% 12% 7% 6% 5% 4 6% 6% 22%	2663
	21st to end	Night	14% 12% 5% 12% 7% 5% 5% 4 6% 7% 25%	2200
March	1st to 10th	Night	15% 10% 4 10% 6% 6% 5% 4 5% 6% 28%	4931
	11th to 20th	Night	9% 9% 4 8% 5% 5% 6% 5% 8% 8% 33%	4979
	21st to end	Night	18% 8% 4 11% 6% 5% 5% 4 5% 6% 30%	5467
April	1st to 10th	Night	18% 11% 3 9% 5% 5% 5% 4 5% 6% 30%	2036
	11th to 20th	Night	17% 8% 3 7% 4 4 4 4 5% 7% 37%	1897
	21st to end	Night	17% 8% 4 9% 5% 4 4 4 4 6% 36%	1800
May	1st to 10th	Night	19% 7% 3 7% 5% 4 4 3 5% 7% 36%	4037
	11th to 20th	Night	12% 6% 2 7% 5% 4 5% 4 6% 8% 41%	3575
	21st to end	Night	17% 6% 2 6% 4 4 4 3 4 7% 42%	3926
June	1st to 10th	Night	14% 6% 2 7% 3 5% 5% 4 6% 8% 41%	1600
	11th to 20th	Night	10% 4 2 6% 5% 6% 5% 5% 7% 9% 42%	1503
	21st to end	Night	10% 7% 3 7% 5% 5% 4 5% 5% 8% 43%	1400
July	1st to 10th	Night	8% 6% 3 7% 5% 4 5% 4 6% 8% 46%	3248
	11th to 20th	Night	10% 5% 2 5% 4 4 4 3 5% 7% 50%	3600
	21st to end	Night	8% 5% 2 5% 4 4 4 3 6% 9% 50%	4291
August	1st to 10th	Night	10% 6% 2 5% 4 5% 3 4 6% 9% 47%	2915
	11th to 20th	Night	13% 5% 2 5% 3 4 3 3 6% 8% 47%	2875
	21st to end	Night	10% 5% 2 6% 4 4 5% 4 6% 8% 46%	3348
September	1st to 10th	Night	11% 5% 2 6% 4 4 4 4 7% 8% 46%	2000
	11th to 20th	Night	12% 4 2 5% 3 3 4 4 5% 8% 51%	2115
	21st to end	Night	16% 7% 2 6% 5% 4 3 3 5% 6% 42%	2240
October	1st to 10th	Night	17% 7% 2 7% 5% 4 4 4 6% 7% 39%	2400
	11th to 20th	Night	17% 10% 4 7% 6% 5% 5% 4 4 6% 31%	2400
	21st to end	Night	21% 11% 3 7% 7% 5% 4 4 6% 6% 26%	2640
November	1st to 10th	Night	17% 10% 3 8% 5% 4 5% 4 5% 7% 31%	2772
	11th to 20th	Night	15% 16% 5% 10% 6% 5% 4 4 6% 6% 23%	2940
	21st to end	Night	18% 17% 5% 9% 6% 5% 5% 4 6% 6% 20%	2940
December	1st to 10th	Night	14% 19% 6% 15% 8% 6% 5% 4 5% 5% 13%	4720
	11th to 20th	Night	14% 15% 6% 14% 7% 6% 6% 4 6% 6% 17%	5348
	21st to end	Night	22% 18% 6% 16% 6% 5% 4 3 5% 5% 11%	7150

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	63% 3 12% 15% 7%	4662
	11th to 20th	Day	74% 3 8% 10% 5%	5058
	21st to end	Day	66% 2 11% 11% 9%	5780
February	1st to 10th	Day	65% 5% 8% 16% 5%	1890
	11th to 20th	Day	63% 3 10% 16% 6% 1	1852
	21st to end	Day	62% 3 11% 16% 6%	1603
March	1st to 10th	Day	55% 3 13% 15% 13% 1	4957
	11th to 20th	Day	54% 3 14% 19% 7% 2	4980
	21st to end	Day	55% 2 8% 20% 13% 1	5465
April	1st to 10th	Day	56% 5% 8% 20% 10% 1	2363
	11th to 20th	Day	48% 4 9% 23% 15% 1	2469
	21st to end	Day	51% 4 11% 19% 13% 3	2600
May	1st to 10th	Day	47% 3 12% 21% 11% 5%	5897
	11th to 20th	Day	48% 4 11% 18% 18% 1	6322
	21st to end	Day	46% 3 12% 22% 14% 3	6949
June	1st to 10th	Day	44% 5% 11% 24% 15% 1	2800
	11th to 20th	Day	38% 5% 13% 26% 15% 1	2889
	21st to end	Day	42% 5% 13% 25% 14% 1	3000
July	1st to 10th	Day	42% 3 15% 24% 15% 1	6638
	11th to 20th	Day	34% 4 12% 32% 17% 1	6285
	21st to end	Day	33% 4 13% 33% 16% 1	6356
August	1st to 10th	Day	43% 4 14% 26% 12% 1	4221
	11th to 20th	Day	41% 5% 18% 27% 10%	4213
	21st to end	Day	36% 5% 14% 33% 12% 1	4516
September	1st to 10th	Day	40% 6% 13% 29% 11% 1	2400
	11th to 20th	Day	38% 4 13% 31% 13% 1	2280
	21st to end	Day	46% 5% 13% 26% 9%	2160
October	1st to 10th	Day	43% 3 13% 26% 14% 1	3260
	11th to 20th	Day	45% 5% 15% 23% 12%	3240
	21st to end	Day	58% 3 16% 17% 5%	3538
November	1st to 10th	Day	55% 5% 13% 20% 6% 1	1743
	11th to 20th	Day	61% 5% 13% 14% 6% 1	1680
	21st to end	Day	69% 5% 10% 13% 2	1680
December	1st to 10th	Day	77% 3 11% 8% 1	2680
	11th to 20th	Day	67% 4 10% 11% 7%	3066
	21st to end	Day	76% 4 8% 8% 5%	4048
January	1st to 10th	Night	67% 3 11% 14% 5%	8234
	11th to 20th	Night	72% 3 10% 10% 6% 1	7884
	21st to end	Night	64% 3 10% 12% 10%	8401
February	1st to 10th	Night	63% 4 10% 18% 5% 1	2730
	11th to 20th	Night	61% 5% 11% 17% 6%	2665
	21st to end	Night	59% 3 12% 18% 8% 1	2200
March	1st to 10th	Night	56% 2 10% 18% 11% 2	4941
	11th to 20th	Night	47% 2 19% 23% 8% 1	4980
	21st to end	Night	55% 2 9% 19% 13% 1	5467
April	1st to 10th	Night	56% 4 9% 19% 11% 1	2036
	11th to 20th	Night	47% 5% 9% 21% 16% 2	1897
	21st to end	Night	51% 3 10% 18% 16% 2	1800
May	1st to 10th	Night	49% 3 12% 16% 15% 6%	4044
	11th to 20th	Night	41% 4 13% 24% 16% 2	3576
	21st to end	Night	43% 3 13% 26% 14% 1	3927
June	1st to 10th	Night	41% 5% 11% 25% 16% 2	1600
	11th to 20th	Night	37% 5% 12% 24% 20% 1	1503
	21st to end	Night	39% 5% 14% 26% 15% 1	1400
July	1st to 10th	Night	37% 3 16% 26% 16% 2	3211
	11th to 20th	Night	34% 4 12% 31% 18% 1	3552
	21st to end	Night	32% 4 11% 34% 17% 1	4163
August	1st to 10th	Night	36% 3 15% 29% 16% 1	2904
	11th to 20th	Night	35% 5% 19% 28% 13% 1	2902
	21st to end	Night	35% 5% 14% 32% 12% 1	3348
September	1st to 10th	Night	36% 5% 15% 31% 12% 1	2000
	11th to 20th	Night	32% 4 13% 34% 16% 1	2115
	21st to end	Night	44% 4 13% 27% 11%	2240
October	1st to 10th	Night	36% 4 10% 28% 21% 1	3920
	11th to 20th	Night	46% 5% 15% 22% 12%	3899
	21st to end	Night	47% 6% 16% 24% 8%	4252
November	1st to 10th	Night	52% 5% 12% 22% 8% 1	2772
	11th to 20th	Night	60% 4 13% 14% 6% 1	2940
	21st to end	Night	65% 5% 14% 14% 1	2940
December	1st to 10th	Night	72% 3 13% 9% 3	4720
	11th to 20th	Night	66% 5% 10% 12% 6%	5348
	21st to end	Night	75% 5% 9% 8% 4	7150

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	15% 10% 42% 24% 8% 1	220
	11th to 20th	Day	18% 10% 41% 22% 7% 2	289
	21st to end	Day	19% 10% 37% 26% 7% 1	363
February	1st to 10th	Day	16% 15% 42% 18% 8% 1	330
	11th to 20th	Day	19% 16% 38% 25% 2	330
	21st to end	Day	24% 18% 29% 26% 2	282
March	1st to 10th	Day	19% 11% 37% 25% 8% 1	508
	11th to 20th	Day	17% 12% 36% 26% 9% 1	500
	21st to end	Day	26% 8% 32% 23% 11% 1	550
April	1st to 10th	Day	19% 15% 31% 24% 9% 2	500
	11th to 20th	Day	25% 10% 28% 20% 12% 5%	492
	21st to end	Day	23% 10% 25% 26% 12% 4	500
May	1st to 10th	Day	17% 7% 26% 31% 15% 5%	503
	11th to 20th	Day	15% 6% 23% 30% 20% 7%	527
	21st to end	Day	17% 4 22% 31% 21% 7%	573
June	1st to 10th	Day	16% 6% 25% 29% 21% 3	530
	11th to 20th	Day	12% 6% 24% 31% 22% 5%	619
	21st to end	Day	17% 5% 25% 31% 18% 5%	730
July	1st to 10th	Day	11% 4 19% 32% 28% 8%	678
	11th to 20th	Day	13% 2 19% 27% 27% 11%	524
	21st to end	Day	10% 2 17% 38% 21% 11%	576
August	1st to 10th	Day	10% 2 17% 27% 30% 13%	526
	11th to 20th	Day	11% 2 16% 27% 28% 15%	519
	21st to end	Day	13% 3 20% 28% 25% 11%	583
September	1st to 10th	Day	13% 5% 21% 23% 25% 12%	530
	11th to 20th	Day	10% 3 16% 24% 25% 21%	530
	21st to end	Day	15% 6% 22% 27% 22% 8%	530
October	1st to 10th	Day	18% 7% 26% 24% 18% 8%	530
	11th to 20th	Day	22% 10% 34% 24% 9% 2	530
	21st to end	Day	29% 9% 31% 23% 8% 1	583
November	1st to 10th	Day	23% 15% 31% 21% 10% 1	285
	11th to 20th	Day	20% 18% 33% 21% 6% 2	220
	21st to end	Day	25% 14% 38% 20% 4	220
December	1st to 10th	Day	20% 16% 37% 21% 5% 1	220
	11th to 20th	Day	20% 18% 36% 19% 6% 1	220
	21st to end	Day	26% 10% 39% 21% 5%	242
January	1st to 10th	Night	21% 9% 42% 21% 7% 1	840
	11th to 20th	Night	24% 9% 34% 27% 7%	840
	21st to end	Night	18% 6% 35% 31% 9% 1	924
February	1st to 10th	Night	19% 9% 40% 28% 4	840
	11th to 20th	Night	19% 9% 36% 29% 6%	823
	21st to end	Night	20% 10% 36% 29% 5%	692
March	1st to 10th	Night	17% 9% 36% 31% 6%	809
	11th to 20th	Night	16% 10% 37% 29% 7% 1	800
	21st to end	Night	21% 7% 31% 29% 11%	880
April	1st to 10th	Night	23% 10% 31% 30% 6%	800
	11th to 20th	Night	20% 7% 31% 30% 10% 2	713
	21st to end	Night	21% 7% 28% 31% 13%	600
May	1st to 10th	Night	19% 3 24% 37% 16% 2	597
	11th to 20th	Night	16% 4 25% 40% 14% 1	394
	21st to end	Night	11% 5% 20% 42% 20% 1	433
June	1st to 10th	Night	15% 5% 25% 41% 14% 1	400
	11th to 20th	Night	10% 6% 20% 47% 17% 1	400
	21st to end	Night	14% 3 20% 43% 19% 2	400
July	1st to 10th	Night	6% 5% 15% 49% 24% 1	390
	11th to 20th	Night	11% 4 20% 41% 22% 2	388
	21st to end	Night	10% 3 17% 43% 26% 2	598
August	1st to 10th	Night	10% 3 12% 43% 30% 2	597
	11th to 20th	Night	7% 2 14% 39% 35% 4	594
	21st to end	Night	12% 4 21% 34% 28% 2	733
September	1st to 10th	Night	12% 5% 19% 34% 23% 7%	800
	11th to 20th	Night	13% 3 18% 31% 26% 9%	800
	21st to end	Night	18% 6% 20% 30% 20% 5%	800
October	1st to 10th	Night	18% 5% 28% 28% 18% 3	800
	11th to 20th	Night	21% 11% 30% 27% 9% 2	800
	21st to end	Night	27% 9% 31% 26% 6%	880
November	1st to 10th	Night	22% 11% 29% 26% 11%	820
	11th to 20th	Night	22% 14% 34% 21% 8% 1	840
	21st to end	Night	28% 13% 33% 23% 4	840
December	1st to 10th	Night	25% 13% 38% 19% 5% 1	840
	11th to 20th	Night	21% 13% 39% 21% 5% 1	840
	21st to end	Night	28% 10% 35% 23% 4	924

Page generated at 2026-02-28 01:40:23. Version ac07

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