Lake of Bays
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake of Bays clear sky chart from 2005-11-06 to 2024-11-05.

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	17% 12% 4 8% 5% 4 4 3 5% 6% 31%	102207
	Night	17% 14% 5% 9% 5% 4 4 3 5% 6% 29%	96840
Transparency	Day	53% 6% 11% 20% 9% 1	105800
	Night	55% 6% 11% 18% 9% 1	101336
Seeing	Day	24% 15% 30% 20% 8% 3	14866
	Night	24% 13% 29% 24% 10% 1	23613

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	15% 24% 11% 15% 5% 3 2 1 3 3 18%	2517
	11th to 20th	Day	11% 18% 10% 17% 10% 7% 4 3 3 4 14%	2589
	21st to end	Day	17% 22% 10% 14% 5% 4 3 2 3 4 16%	3124
February	1st to 10th	Day	12% 21% 7% 16% 7% 5% 3 2 4 4 18%	1710
	11th to 20th	Day	14% 15% 8% 14% 5% 5% 4 3 4 5% 24%	1663
	21st to end	Day	17% 19% 5% 12% 6% 5% 4 3 4 4 21%	1432
March	1st to 10th	Day	18% 17% 4 9% 5% 4 3 3 5% 5% 26%	3422
	11th to 20th	Day	10% 17% 7% 12% 6% 5% 5% 3 6% 6% 24%	3480
	21st to end	Day	13% 12% 4 7% 5% 4 4 3 4 6% 37%	3815
April	1st to 10th	Day	20% 15% 4 7% 5% 5% 4 2 5% 6% 27%	2272
	11th to 20th	Day	23% 11% 3 6% 4 4 4 3 4 5% 34%	2333
	21st to end	Day	22% 12% 4 7% 4 4 3 3 4 5% 33%	2470
May	1st to 10th	Day	19% 8% 3 7% 5% 4 5% 4 5% 8% 32%	4226
	11th to 20th	Day	14% 10% 2 6% 4 4 4 3 6% 9% 36%	4398
	21st to end	Day	17% 7% 2 6% 4 4 4 3 5% 7% 41%	4837
June	1st to 10th	Day	21% 9% 3 6% 5% 4 4 3 6% 7% 32%	2660
	11th to 20th	Day	15% 7% 2 6% 5% 5% 4 4 6% 8% 37%	2803
	21st to end	Day	20% 8% 2 6% 5% 4 4 4 5% 8% 34%	2850
July	1st to 10th	Day	15% 6% 2 7% 5% 5% 6% 4 6% 9% 34%	4760
	11th to 20th	Day	13% 6% 2 7% 5% 4 5% 4 6% 8% 41%	4446
	21st to end	Day	11% 6% 2 5% 4 4 4 4 5% 8% 46%	4697
August	1st to 10th	Day	14% 7% 4 7% 5% 5% 6% 4 6% 8% 33%	4104
	11th to 20th	Day	18% 8% 3 7% 4 3 5% 5% 6% 9% 34%	4044
	21st to end	Day	10% 5% 2 6% 4 4 6% 5% 7% 9% 42%	4357
September	1st to 10th	Day	17% 7% 2 7% 4 4 5% 3 6% 7% 39%	2280
	11th to 20th	Day	16% 6% 2 6% 4 4 4 3 6% 7% 43%	2206
	21st to end	Day	20% 9% 3 6% 4 5% 4 4 4 5% 36%	2028
October	1st to 10th	Day	21% 9% 3 8% 5% 4 4 3 4 6% 33%	1900
	11th to 20th	Day	27% 12% 3 9% 5% 4 5% 3 5% 6% 22%	1900
	21st to end	Day	30% 13% 4 8% 5% 3 3 3 5% 5% 20%	2090
November	1st to 10th	Day	19% 13% 3 8% 7% 3 3 5% 4 6% 28%	1556
	11th to 20th	Day	18% 18% 7% 11% 5% 4 4 3 4 5% 21%	1520
	21st to end	Day	21% 22% 6% 11% 6% 4 4 3 5% 5% 14%	1520
December	1st to 10th	Day	18% 27% 7% 11% 4 4 3 3 3 5% 16%	1520
	11th to 20th	Day	18% 25% 6% 12% 5% 3 3 2 3 3 19%	1906
	21st to end	Day	23% 24% 7% 14% 5% 3 3 2 4 3 13%	2772
January	1st to 10th	Night	17% 22% 10% 15% 5% 4 4 3 4 4 13%	4429
	11th to 20th	Night	13% 18% 7% 19% 9% 5% 5% 3 4 5% 13%	4367
	21st to end	Night	17% 20% 9% 14% 5% 6% 4 3 3 3 15%	4532
February	1st to 10th	Night	13% 19% 7% 13% 8% 5% 4 3 5% 4 18%	2470
	11th to 20th	Night	12% 17% 7% 13% 6% 4 4 3 4 4 25%	2403
	21st to end	Night	16% 17% 6% 12% 6% 5% 4 3 4 5% 22%	2021
March	1st to 10th	Night	16% 14% 5% 9% 6% 4 4 3 5% 6% 29%	3415
	11th to 20th	Night	12% 18% 7% 9% 4 4 4 3 5% 6% 26%	3479
	21st to end	Night	13% 10% 6% 7% 6% 5% 4 4 6% 5% 34%	3817
April	1st to 10th	Night	21% 14% 4 6% 4 4 4 3 4 5% 29%	1907
	11th to 20th	Night	19% 12% 3 6% 5% 4 4 2 5% 6% 35%	1811
	21st to end	Night	21% 9% 3 9% 5% 4 4 4 5% 6% 30%	1710
May	1st to 10th	Night	18% 7% 2 7% 4 4 5% 4 6% 7% 37%	2712
	11th to 20th	Night	16% 8% 2 6% 5% 4 4 4 5% 7% 39%	2495
	21st to end	Night	11% 7% 3 5% 4 4 5% 4 6% 9% 42%	2738
June	1st to 10th	Night	17% 9% 3 6% 5% 5% 5% 4 6% 6% 35%	1520
	11th to 20th	Night	14% 8% 1 5% 4 3 4 3 6% 7% 44%	1370
	21st to end	Night	17% 7% 2 6% 5% 4 5% 4 5% 8% 36%	1330
July	1st to 10th	Night	10% 7% 3 8% 5% 5% 5% 3 5% 6% 42%	2210
	11th to 20th	Night	17% 6% 2 6% 3 3 3 3 5% 6% 46%	2510
	21st to end	Night	11% 6% 2 5% 4 3 4 3 5% 7% 50%	2854
August	1st to 10th	Night	12% 6% 2 6% 4 3 5% 3 6% 8% 46%	2825
	11th to 20th	Night	17% 7% 3 6% 3 3 5% 3 5% 7% 41%	2785
	21st to end	Night	15% 5% 2 5% 3 3 4 3 5% 7% 48%	3266
September	1st to 10th	Night	13% 6% 2 6% 4 3 4 4 7% 7% 44%	1900
	11th to 20th	Night	14% 7% 2 5% 3 4 3 4 5% 7% 47%	1971
	21st to end	Night	19% 7% 3 6% 3 4 3 3 4 7% 41%	2152
October	1st to 10th	Night	20% 9% 3 6% 4 4 4 3 5% 6% 36%	2280
	11th to 20th	Night	24% 12% 3 8% 4 4 3 4 4 6% 27%	2280
	21st to end	Night	27% 16% 4 8% 5% 4 4 3 4 4 22%	2508
November	1st to 10th	Night	21% 15% 3 7% 4 4 4 3 4 6% 29%	2621
	11th to 20th	Night	18% 17% 4 8% 4 4 5% 3 4 6% 25%	2660
	21st to end	Night	22% 19% 5% 10% 6% 5% 4 3 4 5% 16%	2660
December	1st to 10th	Night	20% 26% 7% 11% 5% 4 4 3 4 4 12%	2660
	11th to 20th	Night	19% 23% 7% 13% 5% 4 3 3 3 4 17%	3288
	21st to end	Night	23% 24% 7% 13% 5% 4 3 2 3 4 12%	4884

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	73% 4 7% 9% 6%	2518
	11th to 20th	Day	76% 4 6% 8% 5% 1	2589
	21st to end	Day	74% 5% 6% 8% 6% 1	3124
February	1st to 10th	Day	71% 5% 6% 12% 5% 1	1710
	11th to 20th	Day	64% 5% 9% 12% 9% 1	1672
	21st to end	Day	68% 4 8% 12% 7%	1432
March	1st to 10th	Day	59% 8% 12% 10% 11% 1	3425
	11th to 20th	Day	60% 6% 11% 14% 7% 1	3480
	21st to end	Day	47% 6% 10% 21% 14% 3	3815
April	1st to 10th	Day	58% 5% 9% 17% 9% 2	2272
	11th to 20th	Day	53% 5% 8% 21% 12% 1	2333
	21st to end	Day	55% 5% 8% 18% 12% 3	2470
May	1st to 10th	Day	49% 7% 10% 21% 11% 2	4238
	11th to 20th	Day	43% 9% 12% 25% 10% 1	4402
	21st to end	Day	43% 7% 13% 18% 16% 4	4837
June	1st to 10th	Day	51% 7% 10% 19% 12%	2660
	11th to 20th	Day	44% 8% 11% 23% 14% 1	2803
	21st to end	Day	48% 7% 13% 20% 10% 1	2850
July	1st to 10th	Day	46% 5% 15% 24% 10% 1	4686
	11th to 20th	Day	41% 5% 14% 30% 10%	4370
	21st to end	Day	37% 5% 12% 31% 15%	4547
August	1st to 10th	Day	49% 5% 12% 24% 9% 1	4091
	11th to 20th	Day	47% 5% 14% 25% 8%	4083
	21st to end	Day	37% 6% 11% 35% 10% 1	4357
September	1st to 10th	Day	44% 7% 12% 25% 11% 1	2280
	11th to 20th	Day	39% 8% 12% 28% 13%	2206
	21st to end	Day	50% 6% 11% 24% 9%	2028
October	1st to 10th	Day	50% 4 12% 25% 9% 1	3160
	11th to 20th	Day	55% 6% 11% 21% 8%	3140
	21st to end	Day	64% 4 11% 16% 5%	3428
November	1st to 10th	Day	55% 8% 13% 18% 6%	1556
	11th to 20th	Day	64% 8% 10% 11% 5% 1	1520
	21st to end	Day	73% 6% 9% 8% 3	1520
December	1st to 10th	Day	73% 6% 8% 9% 4 1	1520
	11th to 20th	Day	72% 4 6% 9% 7% 1	1906
	21st to end	Day	77% 4 5% 11% 4	2772
January	1st to 10th	Night	75% 5% 7% 9% 3	4429
	11th to 20th	Night	73% 8% 7% 6% 4 1	4367
	21st to end	Night	73% 7% 6% 8% 6% 1	4532
February	1st to 10th	Night	68% 6% 9% 12% 5% 1	2470
	11th to 20th	Night	63% 4 8% 16% 7%	2405
	21st to end	Night	66% 4 9% 14% 6% 1	2021
March	1st to 10th	Night	56% 6% 12% 15% 11% 1	3425
	11th to 20th	Night	57% 7% 13% 15% 7% 1	3480
	21st to end	Night	48% 7% 10% 21% 13% 2	3817
April	1st to 10th	Night	57% 5% 9% 17% 11% 2	1907
	11th to 20th	Night	50% 5% 7% 22% 14% 1	1811
	21st to end	Night	53% 6% 9% 15% 14% 2	1710
May	1st to 10th	Night	43% 10% 12% 23% 12% 1	2719
	11th to 20th	Night	41% 9% 13% 24% 12% 1	2496
	21st to end	Night	38% 8% 11% 24% 16% 2	2739
June	1st to 10th	Night	47% 9% 11% 19% 13% 2	1520
	11th to 20th	Night	38% 6% 14% 25% 18%	1370
	21st to end	Night	44% 8% 15% 22% 11% 1	1330
July	1st to 10th	Night	42% 5% 13% 24% 15% 1	2175
	11th to 20th	Night	41% 4 12% 33% 11% 1	2463
	21st to end	Night	34% 5% 11% 33% 16% 1	2763
August	1st to 10th	Night	37% 5% 16% 26% 15% 1	2814
	11th to 20th	Night	43% 6% 17% 23% 10% 1	2812
	21st to end	Night	37% 4 12% 34% 12% 1	3266
September	1st to 10th	Night	37% 8% 16% 25% 13% 1	1900
	11th to 20th	Night	36% 7% 14% 29% 14%	1971
	21st to end	Night	45% 5% 13% 27% 11%	2152
October	1st to 10th	Night	42% 4 9% 28% 17%	3800
	11th to 20th	Night	52% 5% 14% 21% 9%	3779
	21st to end	Night	61% 4 15% 15% 6%	4120
November	1st to 10th	Night	55% 6% 13% 19% 6%	2621
	11th to 20th	Night	59% 8% 11% 14% 7% 1	2660
	21st to end	Night	70% 7% 10% 10% 4	2660
December	1st to 10th	Night	76% 6% 6% 8% 3	2660
	11th to 20th	Night	71% 6% 7% 10% 6%	3288
	21st to end	Night	78% 4 6% 8% 4	4884

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% 27% 32% 14% 5% 1	180
	11th to 20th	Day	28% 17% 36% 12% 4 1	201
	21st to end	Day	31% 14% 33% 15% 7%	297
February	1st to 10th	Day	27% 29% 34% 7% 3 1	270
	11th to 20th	Day	29% 26% 38% 7% 1	270
	21st to end	Day	35% 25% 32% 7%	244
March	1st to 10th	Day	24% 21% 36% 17% 1 1	460
	11th to 20th	Day	23% 23% 33% 15% 5% 1	460
	21st to end	Day	30% 16% 32% 17% 4 1	506
April	1st to 10th	Day	27% 22% 28% 16% 6% 1	460
	11th to 20th	Day	36% 20% 19% 13% 8% 3	452
	21st to end	Day	33% 15% 30% 15% 6% 2	460
May	1st to 10th	Day	26% 14% 29% 21% 6% 4	463
	11th to 20th	Day	23% 15% 30% 20% 10% 3	487
	21st to end	Day	22% 16% 31% 20% 9% 3	529
June	1st to 10th	Day	23% 13% 34% 24% 4 1	490
	11th to 20th	Day	17% 14% 31% 25% 11% 2	633
	21st to end	Day	22% 13% 35% 19% 8% 2	680
July	1st to 10th	Day	14% 10% 32% 31% 11% 2	671
	11th to 20th	Day	17% 11% 26% 28% 13% 4	489
	21st to end	Day	14% 11% 32% 28% 11% 5%	532
August	1st to 10th	Day	17% 8% 26% 29% 14% 6%	486
	11th to 20th	Day	19% 5% 24% 29% 15% 8%	479
	21st to end	Day	18% 9% 28% 25% 15% 5%	539
September	1st to 10th	Day	19% 12% 27% 24% 13% 6%	490
	11th to 20th	Day	15% 10% 23% 23% 19% 10%	490
	21st to end	Day	23% 12% 26% 24% 12% 3	490
October	1st to 10th	Day	26% 15% 26% 17% 13% 4	490
	11th to 20th	Day	30% 17% 31% 16% 4 1	490
	21st to end	Day	38% 15% 28% 15% 3	539
November	1st to 10th	Day	32% 19% 30% 15% 3	221
	11th to 20th	Day	33% 19% 33% 9% 5%	180
	21st to end	Day	34% 24% 34% 7% 2	180
December	1st to 10th	Day	34% 17% 36% 11% 3 1	180
	11th to 20th	Day	37% 28% 20% 13% 2 1	180
	21st to end	Day	30% 27% 29% 11% 2 2	198
January	1st to 10th	Night	28% 18% 31% 18% 5%	760
	11th to 20th	Night	30% 17% 31% 17% 4	760
	21st to end	Night	20% 13% 36% 22% 8% 1	836
February	1st to 10th	Night	24% 20% 33% 19% 3	760
	11th to 20th	Night	23% 18% 35% 19% 5%	743
	21st to end	Night	27% 21% 28% 20% 4	628
March	1st to 10th	Night	22% 19% 34% 21% 4	760
	11th to 20th	Night	21% 19% 33% 21% 4 1	760
	21st to end	Night	21% 14% 32% 25% 8%	836
April	1st to 10th	Night	28% 14% 31% 22% 5%	760
	11th to 20th	Night	26% 14% 29% 22% 9% 1	687
	21st to end	Night	26% 10% 29% 25% 10%	570
May	1st to 10th	Night	23% 6% 27% 31% 11% 1	501
	11th to 20th	Night	20% 8% 31% 31% 9%	374
	21st to end	Night	12% 9% 34% 35% 10%	411
June	1st to 10th	Night	19% 8% 30% 33% 9% 1	380
	11th to 20th	Night	17% 9% 24% 38% 12%	380
	21st to end	Night	21% 6% 23% 36% 13% 1	380
July	1st to 10th	Night	12% 5% 23% 43% 17% 1	370
	11th to 20th	Night	15% 5% 24% 36% 19%	368
	21st to end	Night	11% 4 22% 42% 20% 1	482
August	1st to 10th	Night	14% 3 18% 36% 26% 2	567
	11th to 20th	Night	15% 5% 16% 37% 25% 3	564
	21st to end	Night	18% 7% 24% 29% 20% 2	704
September	1st to 10th	Night	16% 6% 26% 31% 17% 3	760
	11th to 20th	Night	16% 7% 24% 26% 23% 4	760
	21st to end	Night	23% 8% 21% 28% 18% 2	760
October	1st to 10th	Night	24% 11% 28% 23% 13% 1	760
	11th to 20th	Night	30% 13% 29% 19% 8% 1	760
	21st to end	Night	35% 13% 31% 17% 4	836
November	1st to 10th	Night	31% 12% 26% 23% 7% 1	760
	11th to 20th	Night	27% 18% 31% 17% 6%	760
	21st to end	Night	35% 15% 27% 18% 5%	760
December	1st to 10th	Night	33% 19% 29% 14% 4	760
	11th to 20th	Night	27% 21% 34% 13% 3 1	760
	21st to end	Night	34% 17% 28% 17% 3	836

Page generated at 2024-11-03 02:11:18. Version ac07

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