Lasqueti Island Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lasqueti Island Observatory clear sky chart from 2005-11-06 to 2024-11-12.

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% 9% 3 7% 5% 4 4 3 5% 6% 35%	105593
	Night	22% 10% 3 8% 5% 4 4 3 5% 6% 29%	102169
Transparency	Day	48% 9% 15% 19% 8% 1	105337
	Night	55% 8% 14% 16% 6% 1	102071
Seeing	Day	19% 5% 18% 25% 23% 8%	15630
	Night	26% 5% 17% 24% 21% 7%	23639

By Month

Percentage Cloud Cover NW (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	35% 13% 4 9% 5% 5% 5% 4 4 5% 11%	2219
	11th to 20th	Day	27% 14% 5% 11% 8% 5% 4 3 5% 5% 12%	2199
	21st to end	Day	41% 19% 5% 9% 5% 4 3 3 3 3 6%	2694
February	1st to 10th	Day	28% 15% 4 10% 5% 5% 5% 3 5% 4 15%	1710
	11th to 20th	Day	24% 12% 4 9% 7% 6% 5% 4 4 5% 21%	1665
	21st to end	Day	21% 12% 5% 8% 7% 6% 5% 4 5% 7% 22%	1413
March	1st to 10th	Day	16% 17% 6% 11% 6% 6% 7% 4 5% 5% 17%	3293
	11th to 20th	Day	17% 10% 3 8% 5% 6% 5% 4 5% 6% 31%	3490
	21st to end	Day	21% 12% 3 9% 6% 5% 4 3 5% 6% 25%	3850
April	1st to 10th	Day	20% 13% 4 8% 6% 5% 4 5% 4 7% 23%	2280
	11th to 20th	Day	17% 10% 5% 8% 6% 5% 4 3 5% 6% 30%	2414
	21st to end	Day	18% 10% 3 8% 5% 5% 4 4 6% 6% 31%	2478
May	1st to 10th	Day	12% 8% 3 7% 4 4 4 3 4 6% 45%	4420
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 4 7% 11% 40%	4377
	21st to end	Day	20% 9% 3 7% 5% 5% 5% 4 5% 6% 31%	5085
June	1st to 10th	Day	17% 8% 3 7% 5% 5% 5% 4 7% 8% 31%	2850
	11th to 20th	Day	12% 7% 3 8% 5% 5% 6% 4 7% 9% 34%	2850
	21st to end	Day	11% 6% 3 7% 5% 5% 4 4 6% 8% 41%	2850
July	1st to 10th	Day	6% 3 1 4 3 2 2 3 3 5% 68%	4740
	11th to 20th	Day	4 3 1 2 3 2 2 2 4 6% 72%	4740
	21st to end	Day	7% 5% 1 4 3 4 4 3 5% 7% 57%	5027
August	1st to 10th	Day	4 3 1 2 2 2 2 2 3 6% 72%	4261
	11th to 20th	Day	11% 6% 3 5% 4 5% 4 4 6% 9% 44%	4026
	21st to end	Day	13% 6% 2 6% 4 4 4 3 5% 6% 46%	4500
September	1st to 10th	Day	9% 5% 2 5% 4 4 4 3 6% 7% 51%	2280
	11th to 20th	Day	15% 8% 3 8% 5% 5% 4 3 5% 6% 40%	2213
	21st to end	Day	21% 9% 3 7% 4 4 4 3 5% 7% 34%	2043
October	1st to 10th	Day	22% 10% 3 8% 5% 5% 4 3 5% 6% 27%	3180
	11th to 20th	Day	28% 10% 3 8% 5% 5% 5% 3 5% 5% 23%	3161
	21st to end	Day	24% 13% 4 9% 5% 5% 5% 4 6% 6% 20%	3150
November	1st to 10th	Day	32% 12% 4 10% 5% 4 5% 3 4 5% 16%	1568
	11th to 20th	Day	27% 14% 4 9% 6% 4 4 3 5% 4 20%	1528
	21st to end	Day	31% 13% 4 9% 6% 5% 4 4 4 5% 15%	1520
December	1st to 10th	Day	26% 17% 5% 10% 5% 4 4 3 5% 5% 18%	1392
	11th to 20th	Day	34% 16% 4 12% 6% 6% 5% 3 3 3 9%	1685
	21st to end	Day	34% 17% 4 10% 6% 4 4 3 3 4 9%	2442
January	1st to 10th	Night	31% 15% 5% 10% 6% 5% 5% 4 3 4 12%	4726
	11th to 20th	Night	28% 11% 3 11% 6% 5% 5% 4 5% 7% 14%	4699
	21st to end	Night	44% 15% 4 8% 5% 4 3 2 3 3 9%	4935
February	1st to 10th	Night	28% 13% 3 9% 5% 5% 3 3 4 5% 20%	2470
	11th to 20th	Night	23% 11% 4 7% 4 5% 4 3 5% 6% 27%	2402
	21st to end	Night	25% 11% 3 8% 5% 4 5% 4 4 5% 24%	2041
March	1st to 10th	Night	22% 13% 4 7% 5% 5% 5% 5% 5% 6% 22%	3575
	11th to 20th	Night	15% 7% 2 9% 5% 5% 6% 4 6% 6% 34%	3489
	21st to end	Night	23% 14% 4 10% 6% 4 4 3 4 4 23%	3803
April	1st to 10th	Night	19% 11% 3 9% 7% 6% 5% 4 5% 7% 24%	1900
	11th to 20th	Night	17% 11% 3 9% 6% 5% 4 4 5% 7% 30%	1712
	21st to end	Night	20% 9% 3 7% 6% 5% 6% 3 7% 6% 28%	1701
May	1st to 10th	Night	13% 8% 3 6% 5% 4 4 3 4 5% 44%	2540
	11th to 20th	Night	12% 6% 2 6% 4 3 3 4 7% 10% 44%	2516
	21st to end	Night	19% 10% 4 10% 7% 4 5% 4 5% 7% 27%	2488
June	1st to 10th	Night	15% 9% 3 9% 5% 4 5% 4 6% 5% 34%	1330
	11th to 20th	Night	13% 8% 4 8% 7% 5% 6% 4 5% 7% 32%	1330
	21st to end	Night	10% 6% 3 7% 5% 5% 4 4 6% 8% 42%	1330
July	1st to 10th	Night	5% 4 2 4 3 4 4 3 4 6% 63%	2220
	11th to 20th	Night	3 2 1 2 2 3 2 2 4 6% 72%	2220
	21st to end	Night	6% 5% 2 5% 5% 4 4 4 6% 6% 54%	2525
August	1st to 10th	Night	5% 3 1 2 2 2 2 2 4 5% 73%	2670
	11th to 20th	Night	11% 6% 3 7% 5% 4 5% 4 6% 8% 43%	2812
	21st to end	Night	11% 6% 3 7% 5% 5% 5% 3 5% 6% 45%	3167
September	1st to 10th	Night	7% 4 2 5% 4 4 4 3 4 6% 58%	1900
	11th to 20th	Night	16% 6% 3 7% 5% 4 3 4 6% 6% 42%	1966
	21st to end	Night	19% 8% 3 6% 4 3 4 3 5% 6% 38%	2137
October	1st to 10th	Night	21% 9% 3 8% 5% 4 5% 3 5% 6% 31%	3800
	11th to 20th	Night	26% 9% 3 7% 4 4 5% 3 5% 6% 27%	3777
	21st to end	Night	24% 10% 4 9% 5% 4 4 3 5% 6% 27%	4407
November	1st to 10th	Night	32% 11% 4 8% 5% 5% 4 3 4 5% 19%	2730
	11th to 20th	Night	28% 13% 3 8% 6% 4 4 4 4 4 21%	2674
	21st to end	Night	30% 12% 4 8% 6% 5% 4 4 4 5% 19%	2660
December	1st to 10th	Night	26% 15% 4 8% 6% 5% 4 3 3 5% 21%	2783
	11th to 20th	Night	36% 17% 5% 9% 5% 5% 4 3 3 4 10%	3520
	21st to end	Night	35% 17% 5% 8% 5% 4 3 3 3 4 13%	5214

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	70% 11% 8% 8% 2	2219
	11th to 20th	Day	69% 10% 10% 7% 4	2220
	21st to end	Day	82% 8% 5% 4 1	2694
February	1st to 10th	Day	71% 10% 7% 8% 3 1	1710
	11th to 20th	Day	64% 10% 10% 12% 4 1	1674
	21st to end	Day	61% 8% 15% 11% 5% 1	1413
March	1st to 10th	Day	63% 11% 12% 9% 5%	3293
	11th to 20th	Day	51% 10% 12% 23% 4	3490
	21st to end	Day	58% 10% 18% 11% 3	3850
April	1st to 10th	Day	59% 10% 15% 12% 4	2280
	11th to 20th	Day	54% 8% 11% 16% 10% 2	2414
	21st to end	Day	53% 9% 12% 17% 9% 1	2478
May	1st to 10th	Day	40% 9% 17% 23% 11% 1	4420
	11th to 20th	Day	35% 13% 23% 25% 5%	4380
	21st to end	Day	52% 11% 16% 16% 5%	5086
June	1st to 10th	Day	49% 11% 17% 15% 6% 2	2850
	11th to 20th	Day	45% 12% 19% 18% 5%	2850
	21st to end	Day	41% 10% 19% 20% 8% 1	2850
July	1st to 10th	Day	21% 6% 12% 28% 26% 8%	4666
	11th to 20th	Day	15% 6% 17% 38% 21% 2	4659
	21st to end	Day	26% 8% 22% 27% 14% 2	4868
August	1st to 10th	Day	17% 6% 15% 49% 13% 1	4244
	11th to 20th	Day	36% 10% 28% 17% 8% 1	4065
	21st to end	Day	38% 9% 20% 24% 8% 1	4499
September	1st to 10th	Day	33% 11% 18% 24% 12% 2	2280
	11th to 20th	Day	45% 10% 15% 18% 11% 1	2213
	21st to end	Day	50% 9% 16% 16% 9%	2043
October	1st to 10th	Day	55% 10% 14% 17% 5%	3180
	11th to 20th	Day	62% 6% 12% 16% 4	3161
	21st to end	Day	64% 8% 12% 12% 4	3150
November	1st to 10th	Day	70% 7% 8% 9% 4	1568
	11th to 20th	Day	66% 9% 10% 10% 4 1	1528
	21st to end	Day	70% 9% 9% 8% 5%	1520
December	1st to 10th	Day	68% 9% 9% 9% 3 1	1392
	11th to 20th	Day	79% 8% 6% 4 2	1688
	21st to end	Day	76% 7% 9% 5% 2	2442
January	1st to 10th	Night	72% 9% 11% 7% 2	4726
	11th to 20th	Night	64% 11% 15% 8% 3	4740
	21st to end	Night	80% 7% 5% 6% 1	4935
February	1st to 10th	Night	67% 8% 10% 9% 4 1	2470
	11th to 20th	Night	57% 10% 13% 12% 6% 1	2404
	21st to end	Night	61% 7% 12% 14% 5% 1	2041
March	1st to 10th	Night	58% 9% 13% 15% 5%	3575
	11th to 20th	Night	46% 12% 13% 25% 4	3490
	21st to end	Night	62% 10% 13% 13% 2	3803
April	1st to 10th	Night	59% 8% 15% 16% 3	1900
	11th to 20th	Night	53% 8% 11% 19% 8% 2	1712
	21st to end	Night	53% 9% 13% 17% 8% 1	1701
May	1st to 10th	Night	40% 6% 16% 27% 10%	2540
	11th to 20th	Night	34% 9% 24% 26% 6% 1	2516
	21st to end	Night	57% 9% 15% 15% 3	2488
June	1st to 10th	Night	51% 9% 15% 17% 6% 2	1330
	11th to 20th	Night	50% 8% 19% 18% 5%	1330
	21st to end	Night	40% 8% 20% 22% 7% 2	1330
July	1st to 10th	Night	24% 7% 12% 25% 26% 7%	2185
	11th to 20th	Night	15% 5% 17% 42% 20% 2	2178
	21st to end	Night	29% 7% 17% 28% 16% 3	2445
August	1st to 10th	Night	16% 5% 12% 44% 23% 1	2662
	11th to 20th	Night	38% 9% 27% 15% 9% 2	2839
	21st to end	Night	39% 7% 20% 26% 8%	3167
September	1st to 10th	Night	28% 8% 17% 31% 14% 3	1900
	11th to 20th	Night	42% 9% 14% 17% 16% 3	1966
	21st to end	Night	47% 8% 16% 19% 8% 2	2137
October	1st to 10th	Night	52% 9% 17% 16% 6%	3800
	11th to 20th	Night	56% 7% 14% 19% 3	3777
	21st to end	Night	57% 8% 17% 14% 4	4407
November	1st to 10th	Night	67% 9% 10% 9% 4 1	2730
	11th to 20th	Night	66% 9% 12% 9% 4 1	2674
	21st to end	Night	66% 9% 9% 10% 5% 1	2660
December	1st to 10th	Night	67% 8% 11% 10% 4 1	2783
	11th to 20th	Night	78% 7% 8% 5% 2	3516
	21st to end	Night	73% 8% 10% 7% 2	5214

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	36% 10% 21% 18% 8% 6%	180
	11th to 20th	Day	39% 8% 19% 21% 12%	180
	21st to end	Day	36% 6% 19% 23% 11% 4	269
February	1st to 10th	Day	34% 10% 24% 16% 15% 1	370
	11th to 20th	Day	28% 5% 26% 25% 13% 2	365
	21st to end	Day	23% 13% 26% 21% 14% 4	307
March	1st to 10th	Day	25% 8% 19% 24% 20% 3	444
	11th to 20th	Day	25% 8% 20% 22% 20% 4	460
	21st to end	Day	27% 7% 24% 25% 14% 4	506
April	1st to 10th	Day	23% 9% 25% 24% 14% 4	460
	11th to 20th	Day	23% 8% 23% 25% 14% 8%	452
	21st to end	Day	20% 7% 23% 28% 17% 5%	460
May	1st to 10th	Day	14% 5% 17% 29% 29% 6%	463
	11th to 20th	Day	15% 4 13% 30% 29% 10%	488
	21st to end	Day	13% 3 17% 31% 27% 8%	684
June	1st to 10th	Day	18% 5% 18% 29% 23% 7%	680
	11th to 20th	Day	11% 4 23% 28% 27% 6%	680
	21st to end	Day	12% 2 17% 29% 30% 11%	680
July	1st to 10th	Day	11% 1 13% 28% 33% 13%	671
	11th to 20th	Day	6% 3 12% 30% 37% 12%	668
	21st to end	Day	5% 2 9% 27% 40% 17%	677
August	1st to 10th	Day	8% 2 9% 20% 38% 24%	487
	11th to 20th	Day	6% 3 10% 27% 36% 19%	477
	21st to end	Day	13% 4 15% 26% 33% 10%	539
September	1st to 10th	Day	11% 4 14% 30% 30% 12%	490
	11th to 20th	Day	20% 4 14% 26% 24% 12%	490
	21st to end	Day	23% 6% 18% 26% 20% 8%	490
October	1st to 10th	Day	26% 4 20% 22% 20% 9%	490
	11th to 20th	Day	32% 6% 17% 20% 18% 8%	490
	21st to end	Day	28% 11% 21% 24% 12% 4	413
November	1st to 10th	Day	33% 7% 30% 19% 10% 2	200
	11th to 20th	Day	34% 10% 15% 20% 15% 6%	182
	21st to end	Day	40% 9% 18% 16% 12% 5%	180
December	1st to 10th	Day	34% 9% 21% 18% 13% 4	180
	11th to 20th	Day	32% 13% 19% 19% 14% 2	180
	21st to end	Day	38% 10% 25% 21% 5% 2	198
January	1st to 10th	Night	39% 10% 19% 18% 11% 3	850
	11th to 20th	Night	37% 7% 17% 17% 19% 3	850
	21st to end	Night	37% 5% 19% 18% 16% 4	891
February	1st to 10th	Night	33% 7% 20% 23% 15% 3	760
	11th to 20th	Night	26% 6% 21% 26% 19% 2	744
	21st to end	Night	29% 8% 18% 24% 16% 4	628
March	1st to 10th	Night	26% 7% 22% 23% 16% 6%	760
	11th to 20th	Night	28% 8% 19% 22% 18% 5%	760
	21st to end	Night	27% 6% 17% 26% 18% 6%	836
April	1st to 10th	Night	24% 6% 19% 26% 20% 6%	760
	11th to 20th	Night	22% 5% 20% 29% 20% 5%	584
	21st to end	Night	22% 5% 18% 29% 20% 5%	561
May	1st to 10th	Night	15% 3 20% 28% 27% 7%	380
	11th to 20th	Night	18% 5% 11% 26% 31% 9%	374
	21st to end	Night	13% 5% 16% 33% 26% 8%	411
June	1st to 10th	Night	18% 6% 12% 34% 24% 5%	380
	11th to 20th	Night	16% 4 16% 32% 23% 8%	380
	21st to end	Night	13% 1 14% 31% 33% 8%	380
July	1st to 10th	Night	12% 1 12% 26% 33% 14%	370
	11th to 20th	Night	6% 2 13% 31% 35% 12%	368
	21st to end	Night	5% 1 9% 28% 41% 16%	416
August	1st to 10th	Night	7% 2 6% 24% 40% 21%	454
	11th to 20th	Night	7% 2 5% 28% 45% 13%	564
	21st to end	Night	11% 3 13% 25% 39% 10%	635
September	1st to 10th	Night	9% 1 10% 31% 34% 15%	760
	11th to 20th	Night	18% 3 13% 18% 29% 18%	760
	21st to end	Night	23% 4 17% 23% 26% 8%	760
October	1st to 10th	Night	21% 5% 13% 26% 25% 10%	760
	11th to 20th	Night	31% 5% 14% 22% 21% 8%	760
	21st to end	Night	31% 7% 18% 25% 14% 5%	836
November	1st to 10th	Night	37% 7% 18% 23% 13% 1	780
	11th to 20th	Night	35% 6% 19% 22% 14% 4	764
	21st to end	Night	36% 7% 18% 22% 14% 4	760
December	1st to 10th	Night	32% 7% 18% 22% 17% 4	818
	11th to 20th	Night	43% 7% 18% 21% 10% 1	850
	21st to end	Night	38% 9% 25% 19% 8% 2	935

Page generated at 2024-11-08 19:45:41. Version ac07

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