Rimouski
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rimouski clear sky chart from 2005-11-06 to 2026-10-29.

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% 10% 3 9% 6% 5% 5% 4 5% 6% 29%	150345
	Night	16% 13% 5% 11% 7% 6% 5% 4 5% 5% 24%	141897
Transparency	Day	54% 7% 14% 18% 7%	153788
	Night	60% 7% 12% 16% 6%	146544
Seeing	Day	22% 12% 29% 25% 10% 2	18534
	Night	23% 12% 29% 26% 9% 1	26378

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	12% 23% 6% 17% 10% 11% 7% 3 3 2 6%	4093
	11th to 20th	Day	9% 15% 7% 22% 14% 7% 6% 4 4 4 7%	4496
	21st to end	Day	3 7% 5% 17% 12% 12% 12% 8% 4 4 14%	5124
February	1st to 10th	Day	7% 11% 5% 12% 12% 10% 7% 5% 5% 6% 19%	1777
	11th to 20th	Day	12% 17% 6% 13% 8% 7% 6% 4 4 4 20%	1849
	21st to end	Day	10% 12% 5% 11% 8% 8% 6% 5% 5% 7% 24%	1730
March	1st to 10th	Day	14% 14% 5% 11% 6% 6% 8% 4 5% 6% 20%	4576
	11th to 20th	Day	19% 17% 4 9% 5% 7% 5% 5% 7% 6% 17%	5090
	21st to end	Day	18% 17% 6% 12% 5% 5% 4 3 4 4 22%	5603
April	1st to 10th	Day	20% 13% 5% 8% 5% 4 4 4 5% 6% 27%	2559
	11th to 20th	Day	19% 12% 4 7% 4 4 3 3 5% 7% 32%	2702
	21st to end	Day	21% 12% 3 7% 3 5% 3 3 5% 5% 33%	2730
May	1st to 10th	Day	21% 11% 3 7% 5% 4 4 4 5% 6% 32%	7639
	11th to 20th	Day	22% 9% 2 6% 4 4 4 4 5% 7% 33%	8555
	21st to end	Day	19% 10% 3 7% 4 4 4 4 5% 7% 33%	9716
June	1st to 10th	Day	19% 8% 3 6% 5% 4 5% 4 7% 6% 32%	3150
	11th to 20th	Day	19% 7% 2 6% 5% 4 4 4 6% 7% 35%	3150
	21st to end	Day	19% 8% 3 8% 5% 5% 5% 5% 5% 8% 30%	3150
July	1st to 10th	Day	14% 6% 2 7% 5% 5% 5% 4 6% 8% 37%	8880
	11th to 20th	Day	16% 7% 2 7% 5% 5% 5% 5% 6% 8% 34%	8880
	21st to end	Day	10% 6% 2 7% 5% 5% 5% 5% 7% 8% 40%	9054
August	1st to 10th	Day	13% 6% 2 7% 4 4 5% 5% 7% 9% 38%	6252
	11th to 20th	Day	16% 6% 3 8% 5% 5% 5% 4 6% 7% 35%	5953
	21st to end	Day	13% 6% 3 7% 4 4 4 4 6% 7% 41%	6594
September	1st to 10th	Day	16% 6% 2 6% 4 4 4 4 5% 7% 42%	2526
	11th to 20th	Day	19% 7% 1 6% 3 3 3 2 4 5% 47%	2310
	21st to end	Day	17% 6% 2 7% 5% 4 4 3 5% 6% 40%	2310
October	1st to 10th	Day	18% 10% 2 6% 5% 4 4 4 5% 7% 36%	2205
	11th to 20th	Day	24% 11% 2 6% 4 4 3 4 5% 6% 29%	2017
	21st to end	Day	24% 13% 2 6% 4 4 5% 3 5% 6% 29%	2052
November	1st to 10th	Day	20% 14% 5% 8% 6% 4 5% 4 6% 5% 25%	1798
	11th to 20th	Day	20% 17% 6% 11% 5% 5% 3 3 4 5% 21%	1680
	21st to end	Day	20% 19% 5% 13% 6% 4 3 3 4 5% 18%	1554
December	1st to 10th	Day	13% 21% 6% 16% 11% 5% 4 2 4 3 14%	2350
	11th to 20th	Day	16% 14% 6% 15% 11% 6% 5% 2 4 4 18%	2688
	21st to end	Day	16% 12% 4 14% 14% 9% 5% 3 4 4 13%	3553
January	1st to 10th	Night	13% 23% 8% 15% 11% 9% 7% 2 3 3 7%	8831
	11th to 20th	Night	9% 19% 8% 17% 9% 7% 5% 4 5% 4 13%	8383
	21st to end	Night	4 9% 5% 17% 10% 9% 14% 8% 5% 5% 16%	9057
February	1st to 10th	Night	9% 13% 6% 13% 10% 8% 7% 4 4 4 22%	2841
	11th to 20th	Night	13% 16% 7% 12% 9% 7% 5% 2 5% 4 20%	2652
	21st to end	Night	11% 14% 5% 12% 9% 8% 5% 4 4 5% 25%	2076
March	1st to 10th	Night	15% 15% 5% 11% 7% 6% 7% 3 4 4 21%	5470
	11th to 20th	Night	19% 19% 5% 10% 7% 5% 5% 3 4 5% 17%	5089
	21st to end	Night	22% 17% 4 9% 6% 5% 4 3 4 5% 22%	5556
April	1st to 10th	Night	23% 15% 4 10% 6% 4 4 3 3 4 25%	2060
	11th to 20th	Night	21% 12% 3 7% 4 3 5% 4 5% 6% 30%	1868
	21st to end	Night	25% 10% 3 6% 3 4 4 3 4 6% 32%	1890
May	1st to 10th	Night	24% 9% 3 7% 4 4 5% 3 5% 6% 31%	5259
	11th to 20th	Night	24% 8% 3 8% 5% 4 4 4 5% 6% 30%	4369
	21st to end	Night	20% 10% 2 7% 5% 5% 5% 3 5% 6% 33%	4491
June	1st to 10th	Night	19% 8% 3 8% 5% 4 5% 4 5% 7% 31%	1470
	11th to 20th	Night	21% 8% 3 6% 4 5% 5% 4 7% 7% 31%	1470
	21st to end	Night	22% 8% 4 7% 5% 5% 5% 4 5% 6% 29%	1470
July	1st to 10th	Night	14% 8% 3 7% 5% 5% 5% 4 6% 8% 34%	4110
	11th to 20th	Night	15% 7% 3 8% 5% 5% 5% 4 7% 9% 32%	4110
	21st to end	Night	11% 7% 3 8% 5% 5% 5% 4 6% 7% 37%	5022
August	1st to 10th	Night	16% 6% 3 7% 6% 6% 6% 4 7% 8% 32%	3850
	11th to 20th	Night	13% 7% 3 10% 6% 7% 6% 5% 8% 8% 28%	4092
	21st to end	Night	16% 7% 2 6% 4 4 4 3 5% 6% 41%	4531
September	1st to 10th	Night	16% 6% 2 7% 5% 4 4 3 6% 6% 40%	2089
	11th to 20th	Night	20% 7% 3 6% 4 4 3 3 5% 6% 39%	2310
	21st to end	Night	18% 6% 2 6% 4 3 3 3 4 6% 44%	2310
October	1st to 10th	Night	20% 8% 2 6% 5% 4 4 3 4 5% 39%	2414
	11th to 20th	Night	25% 10% 3 7% 4 4 3 3 5% 6% 29%	2599
	21st to end	Night	21% 13% 4 8% 4 4 4 3 4 7% 28%	2965
November	1st to 10th	Night	21% 15% 4 9% 5% 4 4 3 4 5% 26%	2720
	11th to 20th	Night	21% 17% 5% 11% 5% 4 4 3 3 4 23%	2940
	21st to end	Night	20% 19% 7% 14% 7% 4 4 3 4 4 15%	3065
December	1st to 10th	Night	13% 17% 8% 16% 10% 6% 5% 3 4 3 13%	5060
	11th to 20th	Night	18% 16% 5% 14% 10% 6% 4 3 4 4 16%	5741
	21st to end	Night	15% 15% 7% 13% 11% 7% 5% 3 4 4 16%	7667

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	83% 5% 6% 4 2	4094
	11th to 20th	Day	77% 7% 8% 6% 3	4526
	21st to end	Day	68% 9% 9% 10% 4	5124
February	1st to 10th	Day	64% 7% 10% 12% 6% 1	1777
	11th to 20th	Day	67% 5% 12% 12% 4	1857
	21st to end	Day	59% 5% 11% 19% 6%	1730
March	1st to 10th	Day	63% 8% 12% 11% 5% 1	4579
	11th to 20th	Day	65% 8% 11% 12% 4	5090
	21st to end	Day	65% 4 8% 16% 6% 2	5603
April	1st to 10th	Day	58% 4 11% 16% 9% 1	2559
	11th to 20th	Day	52% 4 14% 19% 10% 1	2702
	21st to end	Day	53% 5% 9% 19% 12% 2	2730
May	1st to 10th	Day	53% 7% 12% 18% 9% 1	7651
	11th to 20th	Day	48% 9% 13% 20% 9% 1	8559
	21st to end	Day	50% 6% 11% 21% 11% 1	9717
June	1st to 10th	Day	51% 7% 12% 18% 11% 1	3150
	11th to 20th	Day	46% 7% 14% 20% 12% 1	3150
	21st to end	Day	53% 8% 13% 16% 9% 1	3150
July	1st to 10th	Day	44% 6% 14% 26% 11%	8805
	11th to 20th	Day	45% 8% 20% 22% 5%	8799
	21st to end	Day	39% 9% 20% 25% 6%	8854
August	1st to 10th	Day	40% 8% 22% 23% 6%	6238
	11th to 20th	Day	46% 8% 21% 22% 3	5992
	21st to end	Day	40% 8% 22% 23% 8%	6594
September	1st to 10th	Day	41% 7% 17% 24% 10%	2526
	11th to 20th	Day	40% 5% 16% 28% 10% 1	2310
	21st to end	Day	44% 7% 15% 24% 11%	2310
October	1st to 10th	Day	52% 7% 14% 21% 5% 1	3530
	11th to 20th	Day	54% 5% 15% 23% 3	3207
	21st to end	Day	51% 6% 17% 19% 6%	3252
November	1st to 10th	Day	59% 7% 14% 15% 4	1798
	11th to 20th	Day	64% 6% 13% 13% 3	1680
	21st to end	Day	68% 5% 12% 11% 3	1554
December	1st to 10th	Day	75% 5% 10% 9% 1	2350
	11th to 20th	Day	69% 5% 11% 11% 4	2688
	21st to end	Day	71% 7% 9% 10% 2	3553
January	1st to 10th	Night	82% 6% 7% 5%	8831
	11th to 20th	Night	70% 7% 10% 10% 3	8428
	21st to end	Night	65% 9% 9% 13% 4	9057
February	1st to 10th	Night	64% 6% 9% 13% 7% 1	2841
	11th to 20th	Night	67% 5% 10% 13% 5%	2655
	21st to end	Night	61% 5% 9% 17% 7%	2076
March	1st to 10th	Night	65% 8% 8% 12% 7%	5480
	11th to 20th	Night	68% 5% 11% 11% 4	5090
	21st to end	Night	63% 5% 9% 15% 8% 1	5556
April	1st to 10th	Night	64% 4 7% 13% 11% 2	2060
	11th to 20th	Night	53% 6% 8% 18% 13% 1	1868
	21st to end	Night	55% 4 8% 19% 13% 1	1890
May	1st to 10th	Night	53% 6% 11% 18% 12% 1	5265
	11th to 20th	Night	53% 7% 9% 20% 10% 1	4370
	21st to end	Night	50% 8% 9% 18% 14% 1	4492
June	1st to 10th	Night	51% 7% 11% 19% 10% 2	1470
	11th to 20th	Night	49% 7% 11% 18% 13% 2	1470
	21st to end	Night	54% 7% 10% 17% 10% 1	1470
July	1st to 10th	Night	46% 8% 14% 26% 8%	4075
	11th to 20th	Night	46% 8% 20% 23% 3	4068
	21st to end	Night	43% 9% 20% 22% 7%	4907
August	1st to 10th	Night	46% 8% 17% 22% 6%	3840
	11th to 20th	Night	49% 11% 20% 15% 4	4119
	21st to end	Night	42% 8% 15% 24% 11%	4531
September	1st to 10th	Night	42% 8% 15% 25% 10% 1	2089
	11th to 20th	Night	46% 6% 16% 22% 9% 1	2310
	21st to end	Night	42% 5% 12% 26% 14% 1	2310
October	1st to 10th	Night	48% 6% 12% 26% 7%	3869
	11th to 20th	Night	55% 4 13% 24% 3	4148
	21st to end	Night	55% 7% 15% 17% 5%	4715
November	1st to 10th	Night	60% 5% 14% 16% 5% 1	2720
	11th to 20th	Night	65% 5% 12% 14% 4	2940
	21st to end	Night	72% 5% 11% 8% 3	3065
December	1st to 10th	Night	73% 6% 12% 8% 1	5060
	11th to 20th	Night	71% 7% 8% 11% 3	5742
	21st to end	Night	70% 6% 10% 11% 3	7667

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% 16% 36% 17% 5% 1	220
	11th to 20th	Day	21% 20% 27% 21% 9% 1	220
	21st to end	Day	14% 15% 39% 19% 12% 1	242
February	1st to 10th	Day	14% 15% 38% 22% 8% 3	317
	11th to 20th	Day	17% 18% 37% 22% 5%	430
	21st to end	Day	16% 17% 37% 21% 7% 1	446
March	1st to 10th	Day	21% 19% 29% 25% 5% 1	540
	11th to 20th	Day	27% 19% 24% 18% 11% 1	540
	21st to end	Day	24% 15% 31% 21% 7% 2	594
April	1st to 10th	Day	28% 16% 28% 21% 7% 1	540
	11th to 20th	Day	25% 13% 29% 24% 8% 2	532
	21st to end	Day	25% 13% 31% 21% 7% 3	540
May	1st to 10th	Day	27% 12% 29% 22% 8% 2	543
	11th to 20th	Day	25% 8% 28% 26% 12% 2	716
	21st to end	Day	26% 10% 30% 24% 9% 2	845
June	1st to 10th	Day	22% 8% 30% 27% 11% 2	780
	11th to 20th	Day	23% 8% 27% 27% 14% 2	780
	21st to end	Day	21% 8% 25% 31% 13% 2	780
July	1st to 10th	Day	20% 6% 29% 32% 11% 2	770
	11th to 20th	Day	16% 7% 27% 33% 14% 2	768
	21st to end	Day	14% 7% 28% 34% 16% 2	642
August	1st to 10th	Day	14% 7% 25% 35% 16% 2	566
	11th to 20th	Day	16% 6% 22% 36% 17% 3	559
	21st to end	Day	17% 10% 24% 30% 14% 4	627
September	1st to 10th	Day	19% 8% 28% 27% 14% 4	570
	11th to 20th	Day	22% 10% 27% 24% 14% 2	570
	21st to end	Day	18% 11% 28% 26% 12% 5%	570
October	1st to 10th	Day	22% 10% 34% 21% 11% 3	510
	11th to 20th	Day	32% 12% 23% 21% 10% 2	450
	21st to end	Day	32% 15% 26% 20% 6% 1	486
November	1st to 10th	Day	30% 19% 28% 19% 4	425
	11th to 20th	Day	30% 15% 27% 19% 8% 1	430
	21st to end	Day	29% 22% 28% 17% 3	304
December	1st to 10th	Day	25% 17% 30% 19% 8% 2	220
	11th to 20th	Day	26% 24% 32% 14% 5%	220
	21st to end	Day	24% 23% 31% 19% 3 1	242
January	1st to 10th	Night	23% 16% 36% 21% 5%	950
	11th to 20th	Night	22% 19% 32% 21% 6%	869
	21st to end	Night	14% 15% 36% 26% 9%	924
February	1st to 10th	Night	13% 15% 38% 24% 9% 1	840
	11th to 20th	Night	21% 15% 33% 22% 7% 1	823
	21st to end	Night	17% 13% 34% 27% 7% 2	692
March	1st to 10th	Night	20% 15% 31% 26% 7% 1	840
	11th to 20th	Night	27% 15% 28% 21% 8% 1	840
	21st to end	Night	25% 14% 28% 26% 7% 1	924
April	1st to 10th	Night	30% 13% 31% 19% 7% 1	800
	11th to 20th	Night	27% 10% 27% 25% 10% 1	624
	21st to end	Night	29% 9% 25% 25% 10% 1	630
May	1st to 10th	Night	29% 8% 23% 29% 10% 1	630
	11th to 20th	Night	22% 7% 26% 30% 14% 1	468
	21st to end	Night	26% 9% 26% 28% 10% 1	455
June	1st to 10th	Night	21% 7% 23% 36% 13%	420
	11th to 20th	Night	24% 7% 19% 34% 15% 2	420
	21st to end	Night	23% 6% 24% 32% 14% 1	420
July	1st to 10th	Night	19% 4 28% 34% 12% 3	410
	11th to 20th	Night	14% 5% 26% 40% 14% 1	408
	21st to end	Night	17% 4 22% 40% 16% 1	460
August	1st to 10th	Night	16% 4 23% 38% 17% 2	498
	11th to 20th	Night	18% 2 22% 38% 19% 2	622
	21st to end	Night	17% 4 25% 35% 16% 2	693
September	1st to 10th	Night	20% 7% 25% 32% 14% 1	752
	11th to 20th	Night	22% 7% 25% 30% 13% 3	840
	21st to end	Night	19% 8% 27% 31% 13% 1	840
October	1st to 10th	Night	24% 9% 29% 26% 10% 1	840
	11th to 20th	Night	30% 8% 28% 22% 10% 1	840
	21st to end	Night	27% 15% 26% 23% 8%	913
November	1st to 10th	Night	30% 16% 29% 21% 5%	848
	11th to 20th	Night	28% 19% 27% 19% 6% 1	950
	21st to end	Night	27% 17% 30% 20% 6%	950
December	1st to 10th	Night	26% 16% 32% 19% 6% 1	950
	11th to 20th	Night	26% 21% 29% 19% 5% 1	950
	21st to end	Night	24% 18% 27% 23% 6% 1	1045

Page generated at 2026-10-26 04:37:49. Version ac07

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