Lambton Shores
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lambton Shores clear sky chart from 2005-11-06 to 2026-07-01.

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% 11% 4 10% 5% 5% 4 4 5% 7% 32%	137660
	Night	14% 13% 5% 11% 6% 5% 4 3 5% 6% 29%	134757
Transparency	Day	49% 7% 13% 19% 11% 1	141229
	Night	52% 7% 12% 17% 10% 1	139246
Seeing	Day	17% 11% 27% 26% 14% 5%	17314
	Night	20% 10% 29% 28% 12% 1	26661

By Month

Percentage Cloud Cover SE (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	14% 18% 8% 28% 7% 4 4 3 3 3 9%	4590
	11th to 20th	Day	10% 21% 10% 26% 9% 6% 3 2 3 3 5%	4994
	21st to end	Day	15% 18% 6% 12% 9% 6% 6% 4 5% 5% 13%	5780
February	1st to 10th	Day	15% 18% 4 14% 8% 5% 5% 4 5% 4 18%	1890
	11th to 20th	Day	15% 13% 7% 15% 7% 7% 5% 3 4 4 20%	1875
	21st to end	Day	15% 16% 6% 12% 6% 4 5% 4 5% 5% 22%	1730
March	1st to 10th	Day	15% 13% 6% 13% 7% 4 3 3 4 5% 26%	4852
	11th to 20th	Day	11% 14% 5% 11% 5% 4 4 3 6% 8% 30%	5090
	21st to end	Day	17% 15% 6% 11% 5% 4 4 3 4 5% 28%	5586
April	1st to 10th	Day	15% 15% 3 8% 5% 4 4 4 6% 7% 30%	2390
	11th to 20th	Day	17% 11% 3 6% 4 4 5% 3 6% 7% 35%	2702
	21st to end	Day	17% 10% 4 7% 4 4 4 2 5% 7% 35%	2730
May	1st to 10th	Day	15% 8% 3 7% 5% 4 5% 4 6% 7% 37%	7616
	11th to 20th	Day	14% 9% 3 7% 4 4 5% 3 6% 8% 37%	7626
	21st to end	Day	15% 8% 2 6% 4 3 4 3 4 6% 45%	8923
June	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 4 7% 7% 43%	3028
	11th to 20th	Day	9% 6% 3 6% 5% 4 6% 4 7% 9% 41%	3150
	21st to end	Day	11% 6% 2 7% 4 5% 5% 4 6% 8% 43%	3150
July	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 4 7% 9% 41%	6731
	11th to 20th	Day	9% 6% 2 5% 4 4 5% 4 6% 9% 46%	6232
	21st to end	Day	7% 6% 2 6% 4 4 5% 4 6% 10% 46%	6424
August	1st to 10th	Day	12% 6% 2 6% 4 5% 5% 4 7% 10% 39%	4234
	11th to 20th	Day	10% 6% 2 8% 4 5% 5% 5% 7% 11% 37%	4174
	21st to end	Day	9% 6% 3 6% 5% 5% 4 4 7% 8% 43%	4659
September	1st to 10th	Day	10% 7% 2 7% 4 5% 5% 4 7% 7% 42%	2302
	11th to 20th	Day	10% 5% 2 5% 5% 4 5% 3 6% 8% 48%	2200
	21st to end	Day	16% 8% 2 7% 4 5% 5% 4 7% 8% 35%	2200
October	1st to 10th	Day	14% 6% 3 8% 5% 5% 4 4 6% 7% 38%	2069
	11th to 20th	Day	21% 11% 3 9% 5% 4 4 3 5% 7% 28%	2000
	21st to end	Day	24% 14% 4 8% 5% 5% 4 3 4 6% 23%	2117
November	1st to 10th	Day	16% 14% 3 9% 5% 4 4 3 6% 7% 28%	1852
	11th to 20th	Day	16% 16% 6% 10% 6% 4 4 3 6% 6% 23%	1764
	21st to end	Day	18% 21% 8% 11% 6% 5% 5% 3 4 5% 14%	1680
December	1st to 10th	Day	18% 22% 8% 15% 7% 5% 4 3 4 4 10%	2680
	11th to 20th	Day	19% 23% 8% 13% 7% 5% 4 4 4 4 10%	3070
	21st to end	Day	24% 23% 7% 13% 5% 4 4 3 4 4 8%	3570
January	1st to 10th	Night	14% 18% 9% 25% 6% 5% 4 3 3 3 10%	8318
	11th to 20th	Night	10% 20% 9% 19% 9% 6% 5% 3 5% 4 10%	7963
	21st to end	Night	13% 16% 6% 13% 7% 7% 6% 4 5% 5% 17%	8401
February	1st to 10th	Night	15% 16% 5% 13% 9% 5% 6% 3 5% 4 18%	2730
	11th to 20th	Night	15% 15% 6% 11% 6% 5% 6% 4 5% 5% 21%	2626
	21st to end	Night	16% 12% 6% 13% 8% 5% 5% 4 4 5% 21%	2076
March	1st to 10th	Night	15% 13% 3 9% 6% 5% 3 4 5% 6% 31%	5220
	11th to 20th	Night	9% 10% 5% 10% 5% 5% 4 3 6% 8% 34%	5090
	21st to end	Night	16% 12% 4 11% 5% 4 4 3 4 4 33%	5588
April	1st to 10th	Night	18% 13% 3 7% 5% 5% 4 3 6% 6% 30%	2246
	11th to 20th	Night	17% 9% 3 6% 5% 4 4 4 5% 7% 36%	1867
	21st to end	Night	16% 11% 3 7% 5% 4 4 4 5% 7% 34%	1890
May	1st to 10th	Night	16% 8% 3 8% 5% 4 4 3 6% 7% 36%	5237
	11th to 20th	Night	13% 9% 4 8% 5% 4 5% 3 5% 7% 39%	5234
	21st to end	Night	18% 7% 2 4 3 3 4 4 5% 7% 43%	5229
June	1st to 10th	Night	12% 7% 2 5% 4 4 4 3 6% 8% 44%	1586
	11th to 20th	Night	8% 6% 2 7% 5% 4 5% 4 8% 8% 42%	1470
	21st to end	Night	9% 5% 2 6% 5% 4 4 4 5% 8% 47%	1470
July	1st to 10th	Night	7% 6% 2 7% 4 4 5% 4 6% 9% 46%	3243
	11th to 20th	Night	10% 5% 2 5% 4 4 4 3 5% 9% 49%	3738
	21st to end	Night	8% 5% 1 6% 4 4 5% 4 6% 8% 49%	4427
August	1st to 10th	Night	10% 6% 3 6% 4 4 5% 4 5% 7% 45%	2915
	11th to 20th	Night	10% 7% 2 6% 4 4 4 4 5% 7% 46%	2875
	21st to end	Night	8% 7% 2 6% 4 4 5% 3 5% 7% 47%	3223
September	1st to 10th	Night	11% 5% 2 6% 5% 5% 4 4 6% 6% 46%	2076
	11th to 20th	Night	11% 5% 2 4 3 4 4 3 4 6% 54%	2200
	21st to end	Night	15% 8% 3 8% 4 5% 4 4 5% 6% 39%	2200
October	1st to 10th	Night	14% 7% 3 7% 6% 3 4 3 4 6% 42%	2330
	11th to 20th	Night	22% 10% 3 8% 5% 4 3 3 5% 6% 32%	2400
	21st to end	Night	24% 12% 4 8% 5% 5% 4 3 6% 5% 25%	2720
November	1st to 10th	Night	15% 15% 3 7% 5% 4 4 3 5% 6% 33%	2666
	11th to 20th	Night	16% 16% 5% 11% 6% 5% 5% 4 6% 6% 21%	2854
	21st to end	Night	21% 20% 6% 11% 5% 4 4 3 4 4 18%	2940
December	1st to 10th	Night	13% 22% 11% 16% 7% 5% 5% 4 4 4 9%	4720
	11th to 20th	Night	14% 23% 8% 14% 8% 5% 4 3 4 4 15%	5345
	21st to end	Night	21% 21% 8% 14% 6% 5% 4 3 3 4 12%	7644

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	76% 8% 9% 6% 1	4591
	11th to 20th	Day	82% 6% 6% 4 1	4994
	21st to end	Day	67% 8% 10% 8% 6%	5780
February	1st to 10th	Day	66% 8% 10% 12% 4	1890
	11th to 20th	Day	64% 6% 10% 14% 5%	1884
	21st to end	Day	59% 8% 13% 12% 6% 1	1730
March	1st to 10th	Day	58% 6% 14% 16% 5%	4852
	11th to 20th	Day	50% 7% 15% 20% 6% 2	5090
	21st to end	Day	56% 8% 12% 15% 8% 1	5586
April	1st to 10th	Day	50% 7% 13% 20% 9% 1	2390
	11th to 20th	Day	47% 7% 13% 18% 14% 1	2702
	21st to end	Day	48% 7% 14% 18% 12% 2	2730
May	1st to 10th	Day	43% 7% 13% 21% 12% 4	7651
	11th to 20th	Day	43% 9% 14% 21% 12% 2	7630
	21st to end	Day	39% 6% 9% 22% 20% 4	8938
June	1st to 10th	Day	37% 8% 13% 26% 14% 2	3028
	11th to 20th	Day	36% 9% 13% 24% 16% 2	3150
	21st to end	Day	37% 8% 13% 25% 16% 1	3150
July	1st to 10th	Day	36% 7% 13% 24% 18% 1	6658
	11th to 20th	Day	32% 7% 13% 30% 16% 1	6157
	21st to end	Day	31% 8% 16% 25% 20% 1	6240
August	1st to 10th	Day	37% 9% 15% 23% 16% 1	4221
	11th to 20th	Day	37% 9% 16% 30% 8% 1	4213
	21st to end	Day	36% 7% 13% 30% 13% 1	4659
September	1st to 10th	Day	37% 9% 16% 25% 12% 1	2302
	11th to 20th	Day	32% 8% 15% 29% 15% 1	2200
	21st to end	Day	44% 8% 14% 23% 10% 1	2200
October	1st to 10th	Day	35% 8% 13% 28% 15% 2	3368
	11th to 20th	Day	46% 6% 11% 21% 16%	3240
	21st to end	Day	50% 7% 16% 19% 8%	3393
November	1st to 10th	Day	53% 7% 12% 19% 7% 1	1852
	11th to 20th	Day	58% 7% 15% 12% 7% 1	1764
	21st to end	Day	69% 8% 11% 11% 2	1680
December	1st to 10th	Day	72% 9% 10% 7% 1	2680
	11th to 20th	Day	71% 9% 11% 7% 1	3066
	21st to end	Day	79% 7% 8% 5% 2	3570
January	1st to 10th	Night	74% 8% 10% 7% 2	8319
	11th to 20th	Night	73% 8% 9% 7% 3	7963
	21st to end	Night	63% 8% 10% 12% 7%	8401
February	1st to 10th	Night	65% 8% 10% 13% 4 1	2730
	11th to 20th	Night	60% 7% 14% 14% 6%	2628
	21st to end	Night	62% 7% 11% 14% 6%	2076
March	1st to 10th	Night	52% 6% 13% 20% 8% 1	5220
	11th to 20th	Night	43% 7% 18% 22% 9% 1	5090
	21st to end	Night	50% 7% 12% 17% 12% 1	5588
April	1st to 10th	Night	53% 6% 11% 19% 11% 1	2246
	11th to 20th	Night	46% 7% 11% 19% 17% 1	1867
	21st to end	Night	47% 6% 11% 17% 15% 3	1890
May	1st to 10th	Night	46% 7% 11% 16% 15% 5%	5264
	11th to 20th	Night	43% 8% 11% 24% 12% 2	5235
	21st to end	Night	40% 7% 10% 22% 18% 4	5236
June	1st to 10th	Night	36% 6% 12% 24% 19% 2	1586
	11th to 20th	Night	35% 8% 14% 24% 18% 2	1470
	21st to end	Night	33% 7% 14% 26% 19% 1	1470
July	1st to 10th	Night	34% 6% 14% 24% 18% 4	3209
	11th to 20th	Night	32% 6% 13% 28% 19% 2	3693
	21st to end	Night	31% 8% 13% 22% 24% 2	4297
August	1st to 10th	Night	35% 8% 14% 25% 17% 1	2904
	11th to 20th	Night	35% 7% 14% 29% 13% 2	2902
	21st to end	Night	33% 8% 13% 30% 15% 1	3223
September	1st to 10th	Night	36% 8% 14% 27% 14% 2	2076
	11th to 20th	Night	31% 6% 15% 29% 19% 1	2200
	21st to end	Night	44% 7% 13% 22% 13% 1	2200
October	1st to 10th	Night	29% 7% 11% 27% 25% 1	3811
	11th to 20th	Night	48% 5% 12% 19% 15%	3899
	21st to end	Night	48% 6% 14% 21% 10%	4381
November	1st to 10th	Night	49% 6% 13% 22% 10% 1	2666
	11th to 20th	Night	58% 8% 14% 14% 6% 1	2854
	21st to end	Night	66% 7% 13% 11% 2	2940
December	1st to 10th	Night	73% 8% 11% 6% 1	4720
	11th to 20th	Night	69% 8% 10% 9% 4 1	5348
	21st to end	Night	75% 7% 10% 7% 1	7644

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	20% 21% 36% 17% 5% 1	311
	11th to 20th	Day	23% 19% 42% 12% 4 1	330
	21st to end	Day	27% 16% 33% 21% 2 1	363
February	1st to 10th	Day	22% 19% 40% 15% 4 1	330
	11th to 20th	Day	21% 20% 38% 19% 1	330
	21st to end	Day	20% 26% 38% 16% 1	273
March	1st to 10th	Day	23% 17% 37% 18% 4 1	446
	11th to 20th	Day	21% 17% 30% 26% 6% 1	540
	21st to end	Day	25% 15% 31% 22% 7% 1	594
April	1st to 10th	Day	20% 14% 35% 24% 7% 1	540
	11th to 20th	Day	22% 14% 29% 21% 10% 4	532
	21st to end	Day	21% 11% 31% 25% 10% 1	540
May	1st to 10th	Day	21% 10% 29% 27% 11% 2	543
	11th to 20th	Day	17% 9% 26% 28% 16% 5%	567
	21st to end	Day	13% 7% 23% 29% 21% 7%	617
June	1st to 10th	Day	10% 6% 30% 33% 16% 5%	658
	11th to 20th	Day	11% 7% 28% 34% 16% 4	780
	21st to end	Day	13% 6% 25% 37% 16% 4	780
July	1st to 10th	Day	9% 6% 21% 30% 25% 9%	722
	11th to 20th	Day	12% 4 23% 32% 22% 8%	668
	21st to end	Day	8% 3 17% 36% 28% 9%	576
August	1st to 10th	Day	10% 4 13% 33% 26% 13%	526
	11th to 20th	Day	12% 4 17% 30% 24% 14%	519
	21st to end	Day	12% 4 17% 30% 28% 9%	583
September	1st to 10th	Day	13% 5% 23% 26% 22% 12%	530
	11th to 20th	Day	8% 4 17% 26% 31% 15%	530
	21st to end	Day	15% 9% 24% 24% 19% 9%	530
October	1st to 10th	Day	15% 11% 24% 24% 19% 7%	530
	11th to 20th	Day	22% 12% 32% 24% 8% 1	530
	21st to end	Day	27% 16% 30% 21% 5% 1	500
November	1st to 10th	Day	22% 18% 31% 18% 8% 2	330
	11th to 20th	Day	26% 22% 28% 17% 5% 2	264
	21st to end	Day	26% 21% 35% 16% 2	220
December	1st to 10th	Day	24% 23% 28% 20% 4 1	220
	11th to 20th	Day	25% 27% 30% 16% 2	220
	21st to end	Day	29% 18% 37% 14% 2	242
January	1st to 10th	Night	24% 16% 39% 16% 5%	1050
	11th to 20th	Night	26% 16% 34% 20% 3	941
	21st to end	Night	21% 13% 37% 23% 6%	924
February	1st to 10th	Night	24% 11% 40% 23% 2	840
	11th to 20th	Night	22% 15% 31% 28% 5%	823
	21st to end	Night	22% 14% 41% 20% 3	692
March	1st to 10th	Night	20% 12% 34% 27% 6%	840
	11th to 20th	Night	19% 13% 37% 24% 6% 1	840
	21st to end	Night	22% 10% 31% 28% 8% 1	924
April	1st to 10th	Night	22% 14% 29% 29% 5%	826
	11th to 20th	Night	19% 11% 30% 28% 11% 1	623
	21st to end	Night	20% 9% 29% 34% 8% 1	630
May	1st to 10th	Night	18% 6% 27% 36% 12% 2	630
	11th to 20th	Night	15% 5% 27% 39% 13% 1	621
	21st to end	Night	15% 4 22% 39% 19% 2	499
June	1st to 10th	Night	13% 5% 24% 40% 17%	420
	11th to 20th	Night	10% 4 25% 44% 17% 1	420
	21st to end	Night	10% 4 20% 43% 21% 1	420
July	1st to 10th	Night	7% 2 16% 44% 28% 3	422
	11th to 20th	Night	11% 2 16% 38% 28% 4	582
	21st to end	Night	8% 2 16% 47% 26% 2	657
August	1st to 10th	Night	8% 2 13% 39% 33% 4	597
	11th to 20th	Night	10% 3 13% 36% 33% 4	594
	21st to end	Night	10% 3 16% 39% 29% 3	660
September	1st to 10th	Night	12% 6% 19% 33% 25% 6%	781
	11th to 20th	Night	11% 4 16% 34% 29% 6%	800
	21st to end	Night	17% 6% 21% 32% 19% 5%	800
October	1st to 10th	Night	16% 8% 26% 30% 18% 2	800
	11th to 20th	Night	26% 11% 27% 27% 9% 1	800
	21st to end	Night	27% 13% 32% 23% 4	880
November	1st to 10th	Night	23% 12% 30% 24% 9% 1	820
	11th to 20th	Night	25% 16% 33% 19% 6% 1	840
	21st to end	Night	30% 13% 32% 21% 5%	840
December	1st to 10th	Night	27% 18% 34% 18% 4	840
	11th to 20th	Night	24% 19% 37% 18% 3	840
	21st to end	Night	30% 15% 33% 19% 2	1145

Page generated at 2026-06-28 02:10:47. Version ac07

Copyright © 2026 Attilla Danko.