Louiseville
Clear Sky Chart
History

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

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	16% 9% 3 8% 5% 5% 5% 4 6% 7% 33%	101827
	Night	18% 10% 4 8% 5% 4 4 3 5% 6% 32%	97903
Transparency	Day	48% 7% 14% 20% 9% 1	105289
	Night	52% 6% 13% 19% 9% 1	102530
Seeing	Day	21% 9% 27% 26% 14% 4	14632
	Night	23% 7% 28% 32% 11% 1	23562

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	17% 14% 5% 9% 5% 4 4 3 4 5% 30%	2517
	11th to 20th	Day	13% 14% 5% 8% 5% 5% 5% 4 5% 5% 29%	2520
	21st to end	Day	13% 14% 5% 10% 6% 5% 5% 4 5% 6% 27%	2772
February	1st to 10th	Day	13% 17% 4 9% 6% 5% 4 3 4 6% 26%	1605
	11th to 20th	Day	14% 14% 5% 10% 6% 5% 5% 4 5% 5% 27%	1780
	21st to end	Day	16% 15% 4 9% 7% 5% 4 3 5% 5% 28%	1570
March	1st to 10th	Day	20% 10% 3 8% 6% 5% 5% 4 4 6% 29%	3116
	11th to 20th	Day	12% 17% 4 11% 5% 4 5% 4 4 5% 29%	3264
	21st to end	Day	14% 10% 3 8% 5% 5% 4 3 4 6% 38%	4166
April	1st to 10th	Day	21% 10% 3 8% 5% 4 4 3 6% 5% 32%	2280
	11th to 20th	Day	21% 7% 2 6% 4 4 4 4 4 5% 38%	2267
	21st to end	Day	21% 11% 3 7% 5% 3 4 3 5% 6% 32%	2470
May	1st to 10th	Day	20% 7% 3 8% 4 4 4 3 6% 7% 34%	4329
	11th to 20th	Day	15% 7% 3 7% 5% 5% 5% 4 6% 9% 34%	4398
	21st to end	Day	15% 7% 2 7% 5% 5% 5% 4 6% 8% 35%	4837
June	1st to 10th	Day	19% 8% 3 7% 5% 5% 5% 4 6% 8% 29%	2660
	11th to 20th	Day	15% 6% 2 7% 5% 5% 5% 4 6% 9% 36%	2660
	21st to end	Day	19% 7% 3 8% 6% 6% 5% 4 5% 7% 29%	2660
July	1st to 10th	Day	11% 6% 2 9% 6% 5% 5% 5% 7% 9% 36%	4440
	11th to 20th	Day	13% 6% 2 7% 5% 5% 6% 5% 7% 10% 35%	4440
	21st to end	Day	11% 6% 2 6% 4 4 5% 5% 7% 8% 43%	4814
August	1st to 10th	Day	13% 6% 3 7% 5% 5% 6% 6% 8% 11% 31%	4423
	11th to 20th	Day	17% 5% 2 6% 5% 4 5% 3 6% 10% 35%	4087
	21st to end	Day	17% 5% 2 7% 4 4 5% 4 6% 8% 40%	4180
September	1st to 10th	Day	13% 5% 2 5% 5% 4 5% 4 7% 9% 41%	2280
	11th to 20th	Day	14% 6% 2 5% 4 4 3 4 5% 7% 47%	2172
	21st to end	Day	18% 6% 3 6% 4 4 4 4 5% 7% 40%	2090
October	1st to 10th	Day	19% 7% 3 7% 5% 4 5% 3 5% 7% 36%	2000
	11th to 20th	Day	20% 8% 3 8% 5% 6% 6% 4 6% 6% 29%	1815
	21st to end	Day	23% 10% 3 9% 4 4 4 3 4 6% 31%	1881
November	1st to 10th	Day	16% 10% 3 8% 5% 5% 4 4 5% 7% 34%	1761
	11th to 20th	Day	19% 9% 4 7% 5% 4 5% 4 5% 6% 30%	1735
	21st to end	Day	21% 13% 3 7% 5% 5% 4 4 5% 5% 27%	1600
December	1st to 10th	Day	25% 15% 3 9% 5% 5% 4 3 4 4 24%	1560
	11th to 20th	Day	22% 14% 4 9% 6% 4 3 2 4 4 27%	1906
	21st to end	Day	25% 17% 5% 10% 4 2 2 2 4 5% 23%	2772
January	1st to 10th	Night	16% 16% 5% 10% 5% 5% 5% 3 4 5% 26%	4429
	11th to 20th	Night	12% 13% 5% 11% 7% 7% 5% 3 5% 5% 27%	4440
	21st to end	Night	13% 15% 5% 11% 7% 5% 5% 4 4 5% 25%	4884
February	1st to 10th	Night	13% 15% 5% 9% 6% 5% 5% 4 5% 6% 26%	2571
	11th to 20th	Night	14% 12% 5% 10% 6% 6% 4 4 5% 4 29%	2285
	21st to end	Night	16% 13% 4 9% 6% 4 4 3 4 5% 32%	1884
March	1st to 10th	Night	24% 12% 3 7% 5% 3 3 3 5% 4 30%	3724
	11th to 20th	Night	18% 18% 4 9% 5% 4 3 3 4 5% 27%	3695
	21st to end	Night	14% 10% 5% 9% 5% 4 5% 3 4 5% 36%	3466
April	1st to 10th	Night	23% 11% 3 7% 4 4 4 3 4 6% 31%	1900
	11th to 20th	Night	21% 9% 2 6% 5% 5% 4 3 5% 6% 36%	1861
	21st to end	Night	22% 9% 3 6% 4 3 3 3 4 7% 35%	1710
May	1st to 10th	Night	22% 9% 4 7% 5% 4 4 4 6% 5% 30%	2627
	11th to 20th	Night	20% 7% 3 7% 4 4 5% 4 5% 7% 34%	2495
	21st to end	Night	18% 6% 3 7% 5% 5% 5% 4 5% 8% 34%	2738
June	1st to 10th	Night	20% 8% 2 5% 4 4 4 4 7% 8% 34%	1520
	11th to 20th	Night	17% 8% 3 5% 4 3 5% 4 6% 8% 36%	1520
	21st to end	Night	20% 7% 2 7% 4 4 5% 5% 5% 8% 32%	1520
July	1st to 10th	Night	12% 6% 3 8% 6% 5% 7% 4 8% 10% 32%	2520
	11th to 20th	Night	16% 6% 2 7% 5% 4 5% 4 6% 8% 39%	2520
	21st to end	Night	12% 6% 2 5% 4 4 4 4 6% 8% 45%	2739
August	1st to 10th	Night	13% 6% 3 8% 7% 5% 5% 4 6% 8% 35%	2506
	11th to 20th	Night	17% 6% 2 6% 4 4 5% 4 6% 7% 38%	2707
	21st to end	Night	19% 7% 3 7% 4 4 3 3 5% 6% 39%	3476
September	1st to 10th	Night	12% 4 2 6% 5% 5% 4 4 5% 7% 46%	1900
	11th to 20th	Night	15% 5% 2 5% 3 3 4 3 5% 7% 49%	2007
	21st to end	Night	17% 5% 2 6% 3 5% 4 3 4 7% 44%	2090
October	1st to 10th	Night	17% 7% 2 7% 5% 5% 4 3 4 5% 40%	2176
	11th to 20th	Night	21% 9% 2 8% 4 4 4 3 5% 6% 35%	2365
	21st to end	Night	24% 8% 3 7% 4 4 4 3 4 6% 32%	2717
November	1st to 10th	Night	19% 9% 4 8% 5% 4 4 3 4 6% 33%	2537
	11th to 20th	Night	20% 9% 4 7% 5% 4 4 4 5% 6% 33%	2665
	21st to end	Night	23% 13% 4 8% 5% 4 5% 3 4 5% 27%	2800
December	1st to 10th	Night	21% 13% 5% 9% 7% 5% 4 3 5% 5% 23%	2737
	11th to 20th	Night	23% 14% 4 9% 5% 4 3 3 4 4 28%	3288
	21st to end	Night	26% 17% 5% 8% 3 3 3 3 3 4 25%	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	57% 6% 16% 16% 4 1	2518
	11th to 20th	Day	55% 6% 13% 18% 7% 1	2520
	21st to end	Day	56% 8% 11% 19% 6% 1	2772
February	1st to 10th	Day	59% 6% 9% 17% 7% 2	1605
	11th to 20th	Day	57% 6% 13% 12% 10% 1	1789
	21st to end	Day	58% 5% 10% 16% 9% 3	1570
March	1st to 10th	Day	55% 9% 10% 16% 8% 2	3119
	11th to 20th	Day	55% 7% 12% 11% 11% 3	3264
	21st to end	Day	47% 5% 10% 20% 15% 3	4166
April	1st to 10th	Day	53% 6% 11% 16% 12% 2	2280
	11th to 20th	Day	46% 6% 11% 22% 13% 2	2267
	21st to end	Day	53% 6% 10% 16% 12% 3	2470
May	1st to 10th	Day	49% 6% 11% 19% 13% 1	4343
	11th to 20th	Day	44% 10% 20% 16% 9% 2	4402
	21st to end	Day	44% 9% 11% 20% 14% 2	4837
June	1st to 10th	Day	50% 8% 12% 19% 9% 2	2660
	11th to 20th	Day	42% 8% 14% 23% 12% 2	2660
	21st to end	Day	52% 10% 10% 18% 9% 1	2660
July	1st to 10th	Day	42% 9% 16% 24% 9%	4370
	11th to 20th	Day	42% 9% 18% 25% 7%	4365
	21st to end	Day	37% 10% 14% 30% 10%	4661
August	1st to 10th	Day	43% 10% 18% 21% 7%	4409
	11th to 20th	Day	43% 9% 20% 23% 5%	4128
	21st to end	Day	41% 8% 14% 21% 14% 1	4180
September	1st to 10th	Day	37% 8% 17% 25% 11% 1	2280
	11th to 20th	Day	35% 7% 15% 30% 12% 1	2172
	21st to end	Day	43% 8% 14% 26% 10%	2090
October	1st to 10th	Day	47% 6% 14% 25% 7%	3325
	11th to 20th	Day	46% 8% 17% 24% 5% 1	2992
	21st to end	Day	45% 5% 21% 21% 8% 1	3081
November	1st to 10th	Day	49% 8% 13% 20% 9% 1	1761
	11th to 20th	Day	54% 5% 12% 17% 11%	1735
	21st to end	Day	60% 6% 13% 15% 5% 1	1600
December	1st to 10th	Day	65% 5% 10% 14% 6%	1560
	11th to 20th	Day	61% 4 9% 19% 7%	1906
	21st to end	Day	65% 5% 11% 11% 7%	2772
January	1st to 10th	Night	59% 7% 15% 13% 5%	4429
	11th to 20th	Night	58% 6% 13% 18% 4 1	4440
	21st to end	Night	60% 7% 13% 13% 7% 1	4884
February	1st to 10th	Night	59% 6% 10% 16% 8% 1	2571
	11th to 20th	Night	57% 6% 10% 15% 11% 1	2287
	21st to end	Night	54% 5% 9% 17% 13% 2	1884
March	1st to 10th	Night	56% 6% 11% 15% 8% 4	3734
	11th to 20th	Night	60% 5% 8% 14% 11% 2	3696
	21st to end	Night	49% 5% 10% 22% 11% 3	3466
April	1st to 10th	Night	54% 5% 10% 15% 14% 2	1900
	11th to 20th	Night	48% 6% 9% 19% 14% 3	1861
	21st to end	Night	51% 4 9% 18% 15% 3	1710
May	1st to 10th	Night	53% 8% 12% 16% 9% 2	2633
	11th to 20th	Night	46% 8% 16% 17% 11% 2	2496
	21st to end	Night	46% 6% 12% 18% 16% 2	2739
June	1st to 10th	Night	45% 7% 14% 20% 13% 1	1520
	11th to 20th	Night	43% 8% 12% 20% 13% 4	1520
	21st to end	Night	48% 9% 11% 17% 14% 1	1520
July	1st to 10th	Night	46% 8% 17% 19% 10% 1	2480
	11th to 20th	Night	42% 8% 19% 24% 7%	2472
	21st to end	Night	36% 8% 20% 25% 11%	2651
August	1st to 10th	Night	47% 8% 15% 24% 7%	2496
	11th to 20th	Night	44% 8% 18% 23% 7%	2732
	21st to end	Night	45% 7% 12% 22% 13% 1	3476
September	1st to 10th	Night	37% 7% 15% 26% 14% 1	1900
	11th to 20th	Night	36% 6% 15% 31% 11% 1	2007
	21st to end	Night	41% 7% 10% 28% 14%	2090
October	1st to 10th	Night	50% 5% 13% 23% 9%	3631
	11th to 20th	Night	44% 7% 15% 27% 7%	3927
	21st to end	Night	46% 5% 17% 19% 12% 2	4467
November	1st to 10th	Night	52% 6% 13% 20% 8% 1	2537
	11th to 20th	Night	53% 6% 12% 18% 10% 1	2665
	21st to end	Night	61% 5% 12% 15% 7%	2800
December	1st to 10th	Night	64% 5% 13% 13% 5%	2737
	11th to 20th	Night	61% 4 10% 17% 7% 1	3288
	21st to end	Night	65% 4 8% 16% 6% 1	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	26% 12% 31% 24% 7%	180
	11th to 20th	Day	26% 11% 29% 25% 7% 2	180
	21st to end	Day	19% 8% 32% 30% 9% 3	198
February	1st to 10th	Day	25% 11% 42% 20% 2	220
	11th to 20th	Day	23% 8% 36% 25% 7%	388
	21st to end	Day	25% 11% 30% 27% 6% 1	382
March	1st to 10th	Day	24% 9% 29% 29% 9%	460
	11th to 20th	Day	20% 15% 30% 25% 10% 1	460
	21st to end	Day	26% 10% 29% 24% 9% 3	506
April	1st to 10th	Day	25% 12% 26% 26% 11% 1	460
	11th to 20th	Day	26% 13% 27% 22% 10% 2	452
	21st to end	Day	28% 12% 31% 19% 7% 3	460
May	1st to 10th	Day	23% 10% 36% 18% 10% 2	463
	11th to 20th	Day	17% 8% 32% 24% 16% 3	487
	21st to end	Day	19% 12% 32% 21% 13% 2	529
June	1st to 10th	Day	20% 11% 29% 26% 12% 3	490
	11th to 20th	Day	16% 8% 24% 28% 20% 3	490
	21st to end	Day	20% 7% 24% 29% 16% 4	490
July	1st to 10th	Day	13% 6% 21% 33% 22% 6%	485
	11th to 20th	Day	15% 7% 24% 32% 18% 4	484
	21st to end	Day	14% 4 21% 33% 22% 7%	532
August	1st to 10th	Day	15% 5% 20% 32% 23% 6%	486
	11th to 20th	Day	15% 4 18% 32% 20% 12%	479
	21st to end	Day	14% 7% 24% 22% 22% 11%	539
September	1st to 10th	Day	13% 7% 26% 28% 18% 8%	490
	11th to 20th	Day	14% 7% 20% 26% 22% 11%	490
	21st to end	Day	19% 6% 24% 27% 17% 7%	490
October	1st to 10th	Day	21% 9% 23% 25% 19% 3	490
	11th to 20th	Day	24% 8% 29% 25% 12% 2	445
	21st to end	Day	29% 8% 27% 22% 13% 1	429
November	1st to 10th	Day	24% 12% 29% 25% 10% 1	395
	11th to 20th	Day	24% 8% 30% 26% 12% 1	335
	21st to end	Day	30% 11% 32% 19% 9% 1	200
December	1st to 10th	Day	31% 9% 24% 23% 9% 5%	190
	11th to 20th	Day	28% 11% 31% 24% 3 2	180
	21st to end	Day	32% 11% 28% 20% 9% 1	198
January	1st to 10th	Night	28% 9% 28% 29% 6%	760
	11th to 20th	Night	27% 7% 31% 28% 7%	760
	21st to end	Night	17% 6% 30% 38% 8% 1	836
February	1st to 10th	Night	20% 7% 34% 31% 7% 1	760
	11th to 20th	Night	20% 8% 36% 29% 6% 1	743
	21st to end	Night	22% 6% 32% 34% 6%	628
March	1st to 10th	Night	24% 8% 28% 34% 6%	760
	11th to 20th	Night	23% 10% 31% 29% 6% 1	760
	21st to end	Night	21% 8% 33% 29% 9%	836
April	1st to 10th	Night	27% 8% 28% 30% 7%	760
	11th to 20th	Night	26% 10% 31% 27% 6%	737
	21st to end	Night	27% 9% 30% 26% 7%	570
May	1st to 10th	Night	26% 8% 31% 28% 7%	454
	11th to 20th	Night	24% 5% 26% 36% 8% 1	374
	21st to end	Night	21% 4 38% 27% 9%	411
June	1st to 10th	Night	22% 4 27% 34% 11% 1	380
	11th to 20th	Night	20% 4 23% 38% 14% 1	380
	21st to end	Night	24% 4 20% 39% 13%	380
July	1st to 10th	Night	13% 5% 23% 41% 17% 2	370
	11th to 20th	Night	12% 2 24% 44% 17% 1	368
	21st to end	Night	15% 2 20% 45% 17% 1	416
August	1st to 10th	Night	15% 3 15% 43% 23% 1	378
	11th to 20th	Night	17% 2 16% 41% 22% 2	510
	21st to end	Night	17% 4 20% 35% 22% 2	836
September	1st to 10th	Night	15% 4 21% 42% 17% 1	760
	11th to 20th	Night	17% 5% 20% 33% 23% 2	760
	21st to end	Night	19% 6% 24% 31% 18% 2	760
October	1st to 10th	Night	22% 6% 27% 33% 12% 1	760
	11th to 20th	Night	24% 7% 26% 32% 10% 1	760
	21st to end	Night	29% 6% 30% 28% 7%	836
November	1st to 10th	Night	23% 9% 30% 28% 9% 1	780
	11th to 20th	Night	22% 8% 32% 27% 11% 1	800
	21st to end	Night	31% 8% 28% 26% 7% 1	800
December	1st to 10th	Night	29% 7% 29% 27% 7% 1	783
	11th to 20th	Night	25% 9% 31% 26% 8% 1	760
	21st to end	Night	34% 8% 25% 26% 7%	836

Page generated at 2024-12-03 06:45:13. Version ac07

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