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 2025-07-06.

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	17% 11% 4 9% 6% 5% 5% 4 5% 6% 29%	119755
	Night	17% 13% 5% 10% 7% 6% 5% 3 5% 5% 24%	119132
Transparency	Day	54% 7% 14% 18% 7% 1	123241
	Night	60% 7% 11% 15% 6%	123808
Seeing	Day	22% 11% 28% 26% 11% 2	16762
	Night	23% 12% 28% 26% 9% 1	24718

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	14% 25% 7% 17% 11% 10% 4 2 2 2 6%	3157
	11th to 20th	Day	9% 13% 7% 24% 16% 7% 5% 4 4 3 7%	3455
	21st to end	Day	4 8% 4 13% 11% 13% 13% 8% 5% 5% 18%	3960
February	1st to 10th	Day	8% 12% 5% 11% 12% 10% 7% 5% 5% 6% 20%	1692
	11th to 20th	Day	12% 17% 5% 13% 8% 7% 6% 4 4 4 19%	1758
	21st to end	Day	11% 12% 5% 10% 8% 8% 6% 5% 5% 7% 24%	1650
March	1st to 10th	Day	15% 14% 5% 11% 6% 6% 8% 3 5% 6% 20%	4476
	11th to 20th	Day	19% 17% 4 8% 5% 7% 5% 5% 7% 6% 17%	4980
	21st to end	Day	19% 17% 6% 12% 5% 5% 4 3 4 4 22%	5482
April	1st to 10th	Day	20% 13% 5% 7% 5% 4 4 4 4 6% 27%	2437
	11th to 20th	Day	18% 11% 4 7% 4 4 3 3 5% 7% 33%	2572
	21st to end	Day	22% 11% 3 7% 3 4 3 3 5% 5% 33%	2600
May	1st to 10th	Day	19% 10% 3 8% 5% 4 5% 4 5% 5% 33%	5886
	11th to 20th	Day	24% 9% 2 6% 4 4 4 4 5% 6% 32%	6581
	21st to end	Day	19% 7% 2 6% 4 4 4 4 6% 8% 36%	7451
June	1st to 10th	Day	20% 8% 3 6% 5% 4 5% 4 6% 6% 32%	3000
	11th to 20th	Day	19% 7% 2 6% 5% 4 4 4 6% 8% 36%	3000
	21st to end	Day	20% 8% 3 8% 5% 5% 5% 5% 5% 7% 30%	3000
July	1st to 10th	Day	15% 7% 3 7% 5% 5% 5% 4 6% 7% 36%	4835
	11th to 20th	Day	13% 6% 2 7% 5% 5% 6% 5% 7% 8% 37%	4760
	21st to end	Day	11% 5% 2 7% 5% 5% 4 4 7% 7% 43%	4847
August	1st to 10th	Day	12% 5% 2 7% 5% 4 6% 5% 8% 10% 37%	4267
	11th to 20th	Day	17% 6% 2 7% 5% 5% 5% 4 7% 7% 35%	4045
	21st to end	Day	16% 6% 2 6% 4 4 4 4 6% 7% 41%	4532
September	1st to 10th	Day	17% 6% 2 5% 3 4 4 4 5% 7% 42%	2286
	11th to 20th	Day	20% 6% 1 5% 3 3 4 2 4 5% 47%	2090
	21st to end	Day	17% 7% 2 6% 5% 4 4 3 5% 6% 40%	2090
October	1st to 10th	Day	18% 10% 2 6% 5% 4 4 4 5% 6% 36%	1995
	11th to 20th	Day	25% 11% 3 6% 5% 4 3 3 5% 6% 29%	1825
	21st to end	Day	25% 13% 2 6% 4 4 5% 3 5% 6% 28%	1881
November	1st to 10th	Day	19% 14% 5% 9% 6% 4 4 4 6% 4 26%	1711
	11th to 20th	Day	20% 17% 6% 11% 5% 5% 3 3 4 5% 21%	1600
	21st to end	Day	21% 18% 5% 13% 6% 4 3 4 4 5% 18%	1480
December	1st to 10th	Day	13% 21% 6% 17% 11% 5% 4 2 3 3 14%	2280
	11th to 20th	Day	16% 14% 6% 14% 11% 6% 5% 2 4 4 18%	2618
	21st to end	Day	17% 12% 4 14% 14% 8% 5% 3 4 4 13%	3476
January	1st to 10th	Night	14% 27% 9% 17% 12% 7% 4 2 2 2 5%	6808
	11th to 20th	Night	10% 19% 8% 18% 9% 7% 5% 3 4 4 13%	6435
	21st to end	Night	5% 10% 4 12% 10% 10% 14% 6% 5% 5% 19%	6996
February	1st to 10th	Night	9% 14% 6% 13% 10% 8% 7% 4 4 4 21%	2706
	11th to 20th	Night	13% 16% 7% 11% 9% 7% 5% 2 5% 5% 19%	2523
	21st to end	Night	11% 14% 5% 11% 9% 8% 5% 4 4 5% 24%	1980
March	1st to 10th	Night	15% 15% 5% 12% 7% 6% 7% 3 4 4 21%	5350
	11th to 20th	Night	19% 19% 5% 10% 7% 5% 5% 3 4 5% 18%	4979
	21st to end	Night	22% 17% 4 8% 6% 5% 4 3 4 5% 23%	5435
April	1st to 10th	Night	23% 15% 4 10% 6% 4 4 3 3 4 25%	1962
	11th to 20th	Night	21% 12% 2 7% 4 3 5% 4 6% 6% 31%	1778
	21st to end	Night	26% 11% 3 6% 3 4 4 3 4 5% 32%	1800
May	1st to 10th	Night	20% 8% 3 7% 4 4 5% 3 5% 6% 34%	4054
	11th to 20th	Night	25% 9% 3 6% 4 3 4 3 5% 7% 30%	3356
	21st to end	Night	20% 7% 2 6% 5% 5% 5% 4 5% 6% 35%	3446
June	1st to 10th	Night	19% 8% 3 8% 5% 4 5% 4 5% 7% 31%	1400
	11th to 20th	Night	20% 8% 2 6% 4 5% 4 4 7% 8% 33%	1400
	21st to end	Night	23% 8% 4 7% 5% 5% 5% 4 5% 6% 30%	1400
July	1st to 10th	Night	16% 7% 3 7% 5% 5% 5% 4 7% 8% 33%	2245
	11th to 20th	Night	13% 7% 3 8% 5% 5% 5% 5% 8% 10% 31%	2210
	21st to end	Night	12% 6% 3 6% 4 5% 5% 5% 7% 9% 39%	2703
August	1st to 10th	Night	17% 6% 2 7% 6% 6% 5% 4 7% 8% 31%	2630
	11th to 20th	Night	14% 7% 3 9% 6% 7% 5% 5% 8% 7% 29%	2782
	21st to end	Night	19% 7% 2 6% 4 4 4 3 5% 6% 41%	3124
September	1st to 10th	Night	17% 6% 2 7% 5% 4 4 4 6% 6% 40%	1889
	11th to 20th	Night	21% 7% 3 6% 4 4 3 3 4 6% 39%	2090
	21st to end	Night	18% 7% 2 6% 5% 3 3 3 4 6% 43%	2090
October	1st to 10th	Night	20% 7% 2 6% 5% 4 5% 3 5% 5% 39%	2184
	11th to 20th	Night	26% 11% 3 7% 4 4 3 3 5% 6% 28%	2351
	21st to end	Night	22% 14% 4 8% 4 4 3 3 4 7% 27%	2717
November	1st to 10th	Night	21% 14% 4 9% 5% 4 4 3 4 5% 26%	2587
	11th to 20th	Night	21% 17% 5% 11% 5% 4 4 3 3 4 24%	2800
	21st to end	Night	20% 19% 6% 14% 7% 4 4 3 4 4 15%	2919
December	1st to 10th	Night	14% 17% 9% 16% 10% 6% 5% 3 4 3 13%	4910
	11th to 20th	Night	18% 16% 5% 14% 10% 6% 4 3 4 4 16%	5591
	21st to end	Night	15% 15% 7% 13% 11% 7% 5% 3 4 4 16%	7502

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	85% 5% 6% 3 1	3158
	11th to 20th	Day	77% 7% 8% 5% 2	3485
	21st to end	Day	62% 10% 11% 13% 4	3960
February	1st to 10th	Day	64% 7% 10% 12% 6% 1	1692
	11th to 20th	Day	67% 5% 12% 11% 4	1766
	21st to end	Day	59% 5% 11% 19% 6%	1650
March	1st to 10th	Day	63% 8% 12% 10% 5% 1	4479
	11th to 20th	Day	64% 8% 11% 12% 4	4980
	21st to end	Day	65% 4 8% 16% 6% 2	5482
April	1st to 10th	Day	58% 4 11% 16% 10% 1	2437
	11th to 20th	Day	51% 4 14% 19% 11% 1	2572
	21st to end	Day	53% 5% 9% 19% 12% 2	2600
May	1st to 10th	Day	52% 8% 12% 18% 8% 1	5897
	11th to 20th	Day	51% 9% 13% 17% 8% 1	6585
	21st to end	Day	45% 7% 13% 26% 9% 1	7451
June	1st to 10th	Day	51% 7% 11% 18% 11% 1	3000
	11th to 20th	Day	46% 6% 14% 20% 12% 1	3000
	21st to end	Day	52% 8% 13% 17% 10% 1	3000
July	1st to 10th	Day	46% 6% 14% 25% 9%	4760
	11th to 20th	Day	42% 9% 22% 22% 6%	4679
	21st to end	Day	37% 9% 20% 25% 8%	4692
August	1st to 10th	Day	39% 9% 23% 23% 6%	4253
	11th to 20th	Day	46% 9% 22% 19% 4	4084
	21st to end	Day	42% 7% 20% 20% 11%	4532
September	1st to 10th	Day	41% 7% 17% 24% 10%	2286
	11th to 20th	Day	40% 5% 17% 28% 10%	2090
	21st to end	Day	44% 7% 15% 24% 10%	2090
October	1st to 10th	Day	53% 7% 14% 20% 5% 1	3320
	11th to 20th	Day	54% 5% 15% 23% 3	3015
	21st to end	Day	52% 6% 17% 18% 6%	3081
November	1st to 10th	Day	59% 7% 14% 15% 5%	1711
	11th to 20th	Day	64% 6% 13% 14% 3	1600
	21st to end	Day	68% 5% 13% 11% 3	1480
December	1st to 10th	Day	75% 5% 10% 9% 1	2280
	11th to 20th	Day	68% 5% 11% 11% 4	2618
	21st to end	Day	71% 7% 9% 10% 2	3476
January	1st to 10th	Night	85% 6% 5% 3	6808
	11th to 20th	Night	71% 7% 10% 9% 3	6480
	21st to end	Night	61% 10% 10% 14% 4	6996
February	1st to 10th	Night	65% 6% 8% 12% 7% 1	2706
	11th to 20th	Night	67% 5% 10% 12% 5%	2526
	21st to end	Night	62% 5% 9% 17% 6% 1	1980
March	1st to 10th	Night	65% 8% 8% 12% 8%	5360
	11th to 20th	Night	68% 5% 11% 11% 4	4980
	21st to end	Night	62% 5% 9% 15% 9% 1	5435
April	1st to 10th	Night	64% 4 6% 13% 11% 2	1962
	11th to 20th	Night	53% 6% 8% 18% 14% 1	1778
	21st to end	Night	56% 4 8% 19% 12% 1	1800
May	1st to 10th	Night	49% 8% 11% 17% 14% 1	4060
	11th to 20th	Night	52% 7% 10% 21% 10% 1	3357
	21st to end	Night	46% 9% 11% 22% 12% 1	3447
June	1st to 10th	Night	51% 7% 11% 18% 11% 2	1400
	11th to 20th	Night	49% 6% 11% 18% 13% 2	1400
	21st to end	Night	54% 7% 10% 17% 11% 1	1400
July	1st to 10th	Night	47% 8% 13% 26% 6%	2210
	11th to 20th	Night	44% 9% 22% 19% 5%	2168
	21st to end	Night	39% 10% 21% 19% 10%	2617
August	1st to 10th	Night	48% 8% 17% 22% 5%	2620
	11th to 20th	Night	49% 12% 21% 13% 5%	2809
	21st to end	Night	43% 8% 14% 22% 13%	3124
September	1st to 10th	Night	42% 9% 14% 25% 10% 1	1889
	11th to 20th	Night	46% 6% 17% 23% 9% 1	2090
	21st to end	Night	43% 6% 13% 25% 12% 1	2090
October	1st to 10th	Night	48% 6% 12% 26% 8%	3639
	11th to 20th	Night	56% 4 14% 24% 3	3900
	21st to end	Night	56% 7% 15% 17% 4	4467
November	1st to 10th	Night	59% 5% 14% 16% 5% 1	2587
	11th to 20th	Night	64% 5% 12% 14% 5%	2800
	21st to end	Night	73% 5% 12% 7% 3	2919
December	1st to 10th	Night	73% 6% 12% 8% 1	4910
	11th to 20th	Night	71% 7% 8% 11% 3	5592
	21st to end	Night	70% 6% 10% 11% 3	7502

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% 15% 37% 17% 5% 1	200
	11th to 20th	Day	20% 20% 28% 22% 10% 2	200
	21st to end	Day	15% 15% 39% 18% 13% 1	220
February	1st to 10th	Day	15% 15% 40% 22% 7% 2	292
	11th to 20th	Day	17% 18% 37% 22% 6%	399
	21st to end	Day	16% 17% 36% 21% 8% 1	414
March	1st to 10th	Day	20% 17% 30% 27% 5% 1	500
	11th to 20th	Day	25% 19% 24% 19% 12% 1	500
	21st to end	Day	25% 13% 31% 22% 7% 2	550
April	1st to 10th	Day	26% 16% 27% 23% 7% 1	500
	11th to 20th	Day	23% 12% 29% 26% 9% 2	492
	21st to end	Day	26% 12% 31% 22% 6% 3	500
May	1st to 10th	Day	26% 11% 29% 23% 9% 2	503
	11th to 20th	Day	25% 8% 27% 27% 12% 2	669
	21st to end	Day	25% 10% 31% 24% 8% 2	790
June	1st to 10th	Day	22% 8% 29% 27% 11% 2	730
	11th to 20th	Day	22% 8% 27% 27% 14% 2	730
	21st to end	Day	22% 8% 25% 32% 12% 2	730
July	1st to 10th	Day	20% 5% 29% 33% 11% 2	695
	11th to 20th	Day	14% 6% 26% 36% 16% 2	668
	21st to end	Day	14% 5% 26% 36% 16% 2	552
August	1st to 10th	Day	14% 8% 25% 34% 16% 3	486
	11th to 20th	Day	18% 5% 20% 37% 18% 3	479
	21st to end	Day	17% 8% 23% 30% 16% 5%	539
September	1st to 10th	Day	20% 8% 26% 28% 15% 3	490
	11th to 20th	Day	21% 9% 28% 24% 15% 2	490
	21st to end	Day	19% 10% 29% 26% 11% 5%	490
October	1st to 10th	Day	21% 10% 32% 23% 12% 3	440
	11th to 20th	Day	32% 11% 23% 22% 10% 2	390
	21st to end	Day	33% 16% 25% 18% 7% 1	429
November	1st to 10th	Day	28% 18% 29% 20% 4	395
	11th to 20th	Day	31% 15% 27% 19% 8% 1	400
	21st to end	Day	27% 23% 28% 18% 4	280
December	1st to 10th	Day	25% 16% 29% 20% 9% 2	200
	11th to 20th	Day	26% 22% 33% 14% 5% 1	200
	21st to end	Day	24% 21% 31% 19% 3 1	220
January	1st to 10th	Night	23% 16% 36% 20% 5%	900
	11th to 20th	Night	22% 18% 31% 22% 6%	827
	21st to end	Night	14% 14% 36% 27% 9%	880
February	1st to 10th	Night	14% 16% 39% 23% 8% 1	800
	11th to 20th	Night	21% 16% 34% 22% 7% 1	783
	21st to end	Night	18% 13% 33% 27% 7% 2	660
March	1st to 10th	Night	20% 14% 32% 26% 8% 1	800
	11th to 20th	Night	26% 15% 29% 21% 8% 1	800
	21st to end	Night	25% 14% 28% 26% 7% 1	880
April	1st to 10th	Night	29% 13% 31% 19% 7% 1	762
	11th to 20th	Night	27% 9% 27% 26% 10% 1	594
	21st to end	Night	30% 9% 25% 25% 10% 1	600
May	1st to 10th	Night	29% 8% 23% 29% 11% 1	600
	11th to 20th	Night	22% 7% 26% 30% 14% 1	445
	21st to end	Night	25% 9% 26% 28% 11% 1	433
June	1st to 10th	Night	21% 6% 23% 37% 13% 1	400
	11th to 20th	Night	23% 7% 20% 34% 15% 2	400
	21st to end	Night	24% 6% 25% 32% 13% 1	400
July	1st to 10th	Night	18% 4 29% 34% 12% 3	380
	11th to 20th	Night	13% 4 26% 41% 15% 1	368
	21st to end	Night	17% 4 21% 39% 17% 1	416
August	1st to 10th	Night	17% 4 22% 37% 18% 2	450
	11th to 20th	Night	19% 2 22% 36% 20% 2	562
	21st to end	Night	18% 4 23% 36% 17% 3	627
September	1st to 10th	Night	20% 6% 25% 32% 15% 1	680
	11th to 20th	Night	23% 6% 26% 30% 13% 3	760
	21st to end	Night	20% 8% 28% 31% 13% 1	760
October	1st to 10th	Night	23% 9% 29% 27% 11% 1	760
	11th to 20th	Night	31% 8% 27% 23% 11% 1	760
	21st to end	Night	28% 15% 26% 22% 8%	836
November	1st to 10th	Night	28% 16% 29% 22% 5%	805
	11th to 20th	Night	28% 19% 27% 19% 6% 1	900
	21st to end	Night	27% 17% 30% 20% 5%	900
December	1st to 10th	Night	26% 16% 31% 19% 6% 1	900
	11th to 20th	Night	25% 20% 29% 20% 5% 1	900
	21st to end	Night	24% 18% 27% 23% 6% 1	990

Page generated at 2025-07-03 01:30:14. Version ac07

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