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 2025-02-25.

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% 31%	108621
	Night	14% 13% 5% 11% 6% 5% 4 3 5% 6% 28%	110102
Transparency	Day	49% 8% 13% 19% 10% 1	112234
	Night	52% 8% 12% 17% 10% 1	114616
Seeing	Day	17% 10% 27% 26% 15% 5%	15469
	Night	20% 10% 28% 28% 12% 1	24987

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	13% 18% 8% 27% 6% 4 3 3 3 4 11%	3542
	11th to 20th	Day	11% 20% 9% 26% 8% 7% 3 2 3 4 6%	3839
	21st to end	Day	19% 19% 7% 13% 7% 5% 5% 3 5% 5% 13%	4466
February	1st to 10th	Day	15% 18% 5% 14% 8% 5% 5% 4 5% 4 17%	1800
	11th to 20th	Day	15% 13% 7% 15% 7% 7% 5% 3 4 4 20%	1783
	21st to end	Day	16% 16% 6% 11% 6% 4 5% 3 5% 5% 23%	1610
March	1st to 10th	Day	17% 16% 5% 10% 5% 4 3 3 4 5% 27%	3302
	11th to 20th	Day	12% 15% 5% 11% 6% 4 4 3 5% 7% 29%	3480
	21st to end	Day	17% 13% 4 10% 4 4 4 4 5% 6% 31%	3815
April	1st to 10th	Day	14% 15% 3 8% 5% 4 4 4 6% 8% 31%	2162
	11th to 20th	Day	17% 11% 2 6% 4 4 4 3 6% 7% 36%	2442
	21st to end	Day	18% 10% 4 7% 4 4 4 2 5% 7% 35%	2470
May	1st to 10th	Day	16% 7% 3 6% 4 4 4 4 6% 7% 37%	4082
	11th to 20th	Day	17% 9% 3 8% 4 4 4 3 6% 8% 34%	4081
	21st to end	Day	11% 6% 2 6% 4 4 4 3 5% 8% 47%	4756
June	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 4 7% 7% 42%	2740
	11th to 20th	Day	9% 5% 3 6% 4 4 6% 4 7% 9% 43%	2850
	21st to end	Day	12% 6% 2 6% 4 5% 5% 4 6% 8% 43%	2850
July	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 4 7% 9% 41%	4698
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 4 6% 10% 47%	4354
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 4 7% 10% 43%	4466
August	1st to 10th	Day	12% 7% 2 6% 4 5% 5% 4 7% 9% 39%	4104
	11th to 20th	Day	10% 6% 2 8% 4 5% 5% 5% 8% 11% 38%	4044
	21st to end	Day	9% 6% 3 6% 5% 5% 5% 4 7% 8% 43%	4516
September	1st to 10th	Day	10% 7% 2 7% 4 5% 5% 4 7% 7% 42%	2187
	11th to 20th	Day	11% 5% 2 5% 5% 4 5% 4 6% 8% 46%	2090
	21st to end	Day	16% 8% 2 7% 4 5% 5% 4 7% 8% 35%	2090
October	1st to 10th	Day	15% 6% 3 8% 5% 5% 4 4 6% 7% 36%	1966
	11th to 20th	Day	21% 11% 3 9% 5% 4 4 4 5% 6% 26%	1900
	21st to end	Day	25% 14% 4 8% 5% 5% 4 3 4 7% 22%	2011
November	1st to 10th	Day	16% 13% 3 10% 5% 5% 4 3 6% 7% 28%	1762
	11th to 20th	Day	15% 16% 6% 10% 7% 4 4 3 6% 6% 22%	1680
	21st to end	Day	18% 21% 8% 11% 7% 6% 5% 3 4 5% 14%	1600
December	1st to 10th	Day	18% 22% 8% 15% 7% 5% 4 3 4 4 10%	2600
	11th to 20th	Day	20% 23% 8% 13% 7% 5% 4 4 4 4 10%	2990
	21st to end	Day	24% 23% 7% 13% 5% 4 4 3 4 4 8%	3493
January	1st to 10th	Night	14% 18% 10% 24% 6% 4 4 3 3 3 11%	6421
	11th to 20th	Night	12% 19% 9% 18% 10% 6% 5% 3 4 5% 9%	6113
	21st to end	Night	17% 17% 7% 13% 6% 6% 5% 3 5% 5% 16%	6490
February	1st to 10th	Night	16% 16% 5% 13% 9% 5% 6% 3 5% 4 17%	2600
	11th to 20th	Night	15% 16% 6% 11% 7% 5% 6% 4 5% 5% 20%	2498
	21st to end	Night	16% 12% 6% 12% 8% 6% 5% 4 4 5% 22%	1939
March	1st to 10th	Night	16% 15% 3 8% 5% 4 3 3 5% 5% 32%	3550
	11th to 20th	Night	10% 10% 5% 10% 6% 5% 4 3 6% 7% 33%	3480
	21st to end	Night	15% 11% 3 10% 5% 4 4 3 4 5% 35%	3817
April	1st to 10th	Night	18% 13% 3 7% 4 5% 3 3 6% 6% 31%	2033
	11th to 20th	Night	18% 8% 3 5% 5% 4 4 4 5% 7% 36%	1687
	21st to end	Night	17% 12% 3 7% 5% 4 4 4 5% 7% 34%	1710
May	1st to 10th	Night	16% 8% 3 7% 5% 4 4 3 6% 8% 37%	2813
	11th to 20th	Night	12% 9% 3 8% 5% 4 5% 4 5% 7% 37%	2812
	21st to end	Night	12% 5% 2 4 3 4 4 4 7% 8% 49%	2797
June	1st to 10th	Night	12% 7% 3 6% 5% 4 4 3 6% 8% 43%	1435
	11th to 20th	Night	8% 6% 2 7% 4 4 5% 5% 8% 8% 43%	1330
	21st to end	Night	10% 5% 2 6% 5% 4 4 4 6% 8% 47%	1330
July	1st to 10th	Night	7% 4 2 6% 4 4 4 3 6% 9% 50%	2267
	11th to 20th	Night	10% 4 2 4 3 3 3 3 5% 9% 52%	2612
	21st to end	Night	5% 5% 1 6% 4 5% 6% 5% 7% 9% 46%	3087
August	1st to 10th	Night	10% 6% 3 6% 4 4 5% 4 5% 7% 45%	2825
	11th to 20th	Night	10% 7% 2 6% 4 4 4 4 6% 7% 45%	2785
	21st to end	Night	8% 7% 2 6% 4 4 5% 3 5% 7% 47%	3124
September	1st to 10th	Night	11% 5% 2 6% 5% 5% 4 4 6% 6% 46%	1972
	11th to 20th	Night	12% 5% 2 5% 4 4 4 4 4 6% 52%	2090
	21st to end	Night	15% 8% 3 8% 4 5% 4 4 5% 6% 38%	2090
October	1st to 10th	Night	14% 8% 3 7% 6% 4 4 3 4 6% 41%	2213
	11th to 20th	Night	22% 10% 3 8% 5% 5% 3 3 5% 6% 31%	2280
	21st to end	Night	24% 12% 4 8% 5% 4 4 4 6% 5% 23%	2584
November	1st to 10th	Night	16% 14% 3 7% 5% 4 4 3 5% 6% 33%	2536
	11th to 20th	Night	17% 17% 5% 10% 6% 5% 4 4 5% 6% 20%	2718
	21st to end	Night	21% 19% 6% 11% 5% 4 4 3 4 4 19%	2800
December	1st to 10th	Night	13% 22% 11% 16% 7% 5% 5% 4 4 4 9%	4580
	11th to 20th	Night	14% 23% 8% 14% 8% 5% 4 3 4 4 14%	5205
	21st to end	Night	21% 21% 8% 14% 6% 5% 4 3 3 4 12%	7479

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	3543
	11th to 20th	Day	81% 7% 7% 3 1	3839
	21st to end	Day	69% 8% 11% 7% 4 1	4466
February	1st to 10th	Day	66% 8% 10% 11% 4	1800
	11th to 20th	Day	65% 6% 10% 13% 5%	1792
	21st to end	Day	59% 9% 13% 12% 6% 1	1610
March	1st to 10th	Day	57% 8% 11% 19% 4	3302
	11th to 20th	Day	51% 9% 15% 18% 7% 1	3480
	21st to end	Day	51% 9% 13% 15% 10% 2	3815
April	1st to 10th	Day	49% 8% 14% 20% 9% 1	2162
	11th to 20th	Day	47% 7% 14% 17% 14% 2	2442
	21st to end	Day	48% 7% 14% 17% 12% 2	2470
May	1st to 10th	Day	43% 8% 13% 19% 14% 3	4120
	11th to 20th	Day	45% 11% 17% 18% 9% 1	4085
	21st to end	Day	34% 8% 12% 19% 21% 6%	4770
June	1st to 10th	Day	38% 9% 14% 26% 13% 1	2740
	11th to 20th	Day	35% 9% 13% 24% 17% 2	2850
	21st to end	Day	38% 8% 13% 24% 16% 1	2850
July	1st to 10th	Day	37% 7% 15% 23% 16% 2	4625
	11th to 20th	Day	31% 7% 14% 33% 14% 1	4279
	21st to end	Day	33% 9% 18% 19% 20% 1	4324
August	1st to 10th	Day	38% 9% 15% 22% 15% 1	4091
	11th to 20th	Day	37% 9% 16% 29% 8% 1	4083
	21st to end	Day	36% 7% 13% 30% 13% 1	4516
September	1st to 10th	Day	38% 9% 16% 24% 12% 1	2187
	11th to 20th	Day	33% 8% 15% 28% 15% 1	2090
	21st to end	Day	45% 9% 14% 23% 10% 1	2090
October	1st to 10th	Day	35% 8% 13% 27% 14% 2	3265
	11th to 20th	Day	46% 6% 11% 21% 16%	3140
	21st to end	Day	51% 7% 16% 19% 7%	3287
November	1st to 10th	Day	53% 7% 13% 19% 7% 1	1762
	11th to 20th	Day	58% 7% 15% 12% 8% 1	1680
	21st to end	Day	69% 8% 11% 11% 2	1600
December	1st to 10th	Day	72% 10% 11% 6% 1	2600
	11th to 20th	Day	72% 9% 11% 7% 1	2986
	21st to end	Day	79% 7% 8% 5% 2	3493
January	1st to 10th	Night	73% 8% 10% 8% 2	6421
	11th to 20th	Night	73% 9% 10% 6% 2	6113
	21st to end	Night	65% 8% 11% 10% 6%	6490
February	1st to 10th	Night	66% 8% 10% 12% 4	2600
	11th to 20th	Night	61% 7% 13% 14% 6%	2500
	21st to end	Night	61% 7% 12% 14% 6%	1939
March	1st to 10th	Night	52% 6% 12% 24% 5%	3550
	11th to 20th	Night	42% 9% 17% 20% 10% 1	3480
	21st to end	Night	47% 8% 13% 20% 11% 1	3817
April	1st to 10th	Night	51% 6% 11% 20% 11% 1	2033
	11th to 20th	Night	45% 7% 11% 18% 16% 2	1687
	21st to end	Night	48% 6% 11% 17% 14% 4	1710
May	1st to 10th	Night	43% 9% 11% 18% 15% 4	2840
	11th to 20th	Night	42% 10% 12% 23% 10% 2	2813
	21st to end	Night	30% 9% 12% 21% 22% 5%	2804
June	1st to 10th	Night	37% 7% 13% 25% 16% 2	1435
	11th to 20th	Night	34% 9% 14% 23% 19% 2	1330
	21st to end	Night	33% 7% 15% 25% 18% 1	1330
July	1st to 10th	Night	30% 6% 13% 28% 17% 6%	2231
	11th to 20th	Night	29% 6% 14% 32% 18% 1	2564
	21st to end	Night	30% 10% 16% 20% 21% 3	2988
August	1st to 10th	Night	36% 8% 14% 25% 16% 1	2814
	11th to 20th	Night	36% 7% 14% 29% 13% 1	2812
	21st to end	Night	34% 8% 13% 29% 15% 1	3124
September	1st to 10th	Night	36% 9% 14% 25% 14% 2	1972
	11th to 20th	Night	32% 6% 15% 28% 19% 1	2090
	21st to end	Night	44% 7% 13% 22% 12% 1	2090
October	1st to 10th	Night	30% 7% 11% 27% 24% 1	3694
	11th to 20th	Night	48% 5% 13% 19% 15%	3779
	21st to end	Night	48% 7% 14% 21% 10%	4245
November	1st to 10th	Night	48% 6% 13% 22% 10% 1	2536
	11th to 20th	Night	59% 8% 14% 13% 6% 1	2718
	21st to end	Night	66% 7% 14% 11% 2	2800
December	1st to 10th	Night	73% 8% 11% 6% 1	4580
	11th to 20th	Night	69% 9% 10% 9% 4 1	5208
	21st to end	Night	75% 7% 10% 7% 1	7479

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% 21% 36% 18% 6% 1	283
	11th to 20th	Day	22% 17% 43% 13% 5% 1	300
	21st to end	Day	27% 15% 33% 22% 2 1	330
February	1st to 10th	Day	23% 19% 41% 14% 3	300
	11th to 20th	Day	21% 19% 39% 20% 1	300
	21st to end	Day	20% 26% 38% 16% 1	237
March	1st to 10th	Day	23% 16% 36% 19% 5% 1	374
	11th to 20th	Day	18% 16% 30% 27% 7% 1	460
	21st to end	Day	25% 13% 31% 23% 8% 1	506
April	1st to 10th	Day	17% 12% 35% 26% 8% 1	460
	11th to 20th	Day	22% 13% 28% 22% 10% 4	452
	21st to end	Day	23% 10% 30% 25% 11% 2	460
May	1st to 10th	Day	21% 10% 26% 27% 13% 3	463
	11th to 20th	Day	17% 7% 24% 29% 17% 5%	487
	21st to end	Day	12% 5% 21% 31% 24% 8%	529
June	1st to 10th	Day	11% 5% 27% 34% 17% 5%	570
	11th to 20th	Day	11% 6% 26% 35% 18% 4	680
	21st to end	Day	14% 6% 23% 36% 17% 4	680
July	1st to 10th	Day	8% 5% 20% 30% 26% 10%	671
	11th to 20th	Day	11% 4 23% 31% 22% 8%	621
	21st to end	Day	8% 3 15% 36% 28% 9%	532
August	1st to 10th	Day	11% 3 14% 32% 26% 13%	486
	11th to 20th	Day	11% 4 17% 30% 24% 14%	479
	21st to end	Day	12% 4 17% 29% 29% 9%	539
September	1st to 10th	Day	13% 5% 22% 27% 22% 11%	490
	11th to 20th	Day	8% 4 18% 26% 30% 14%	490
	21st to end	Day	15% 9% 25% 24% 19% 8%	490
October	1st to 10th	Day	15% 12% 24% 24% 18% 7%	490
	11th to 20th	Day	23% 12% 32% 24% 8% 1	490
	21st to end	Day	28% 16% 30% 20% 5% 1	460
November	1st to 10th	Day	20% 19% 30% 19% 9% 2	300
	11th to 20th	Day	26% 19% 31% 18% 5% 2	240
	21st to end	Day	25% 21% 36% 16% 3	200
December	1st to 10th	Day	24% 24% 28% 21% 4 1	200
	11th to 20th	Day	26% 24% 31% 17% 3	200
	21st to end	Day	28% 18% 37% 15% 2	220
January	1st to 10th	Night	24% 15% 39% 16% 5% 1	1000
	11th to 20th	Night	27% 15% 33% 21% 3	896
	21st to end	Night	21% 12% 37% 24% 6%	880
February	1st to 10th	Night	24% 11% 41% 22% 2	800
	11th to 20th	Night	22% 14% 31% 28% 5%	783
	21st to end	Night	21% 13% 42% 20% 3	647
March	1st to 10th	Night	20% 11% 34% 29% 7%	760
	11th to 20th	Night	17% 11% 38% 25% 7% 1	760
	21st to end	Night	22% 9% 30% 29% 9% 1	836
April	1st to 10th	Night	22% 13% 29% 30% 6%	748
	11th to 20th	Night	20% 10% 30% 28% 11% 1	563
	21st to end	Night	20% 8% 28% 34% 9% 1	570
May	1st to 10th	Night	18% 5% 25% 36% 13% 2	570
	11th to 20th	Night	15% 4 26% 39% 14% 2	561
	21st to end	Night	13% 4 20% 40% 21% 2	451
June	1st to 10th	Night	14% 5% 23% 41% 17% 1	380
	11th to 20th	Night	9% 4 23% 44% 18% 1	380
	21st to end	Night	11% 4 19% 42% 22% 1	380
July	1st to 10th	Night	7% 2 16% 43% 29% 3	400
	11th to 20th	Night	11% 2 16% 38% 29% 4	552
	21st to end	Night	8% 2 16% 46% 26% 2	624
August	1st to 10th	Night	9% 2 13% 39% 33% 4	567
	11th to 20th	Night	10% 3 14% 35% 34% 4	564
	21st to end	Night	11% 3 17% 37% 29% 3	627
September	1st to 10th	Night	12% 6% 18% 34% 24% 6%	742
	11th to 20th	Night	11% 4 17% 34% 27% 6%	760
	21st to end	Night	17% 6% 21% 32% 18% 5%	760
October	1st to 10th	Night	17% 8% 26% 29% 18% 2	760
	11th to 20th	Night	27% 11% 26% 26% 10% 1	760
	21st to end	Night	28% 13% 32% 22% 4	836
November	1st to 10th	Night	24% 11% 29% 25% 10% 1	780
	11th to 20th	Night	25% 16% 33% 18% 6% 1	800
	21st to end	Night	29% 14% 31% 22% 5%	800
December	1st to 10th	Night	27% 18% 34% 17% 4	800
	11th to 20th	Night	25% 18% 36% 18% 3	800
	21st to end	Night	30% 14% 33% 20% 3	1090

Page generated at 2025-02-22 06:51:33. Version ac07

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