Saint-Mathieu-de-Rioux
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Mathieu-de-Rioux clear sky chart from 2005-11-06 to 2026-10-14.

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 10% 7% 6% 5% 4 5% 6% 25%	150152
	Night	15% 13% 4 10% 7% 6% 6% 4 5% 5% 25%	141808
Transparency	Day	58% 7% 12% 16% 7% 1	153595
	Night	59% 7% 12% 15% 6% 1	146455
Seeing	Day	27% 20% 30% 16% 6% 1	18592
	Night	25% 17% 29% 22% 7% 1	26379

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	11% 21% 8% 17% 8% 10% 9% 3 3 3 6%	4093
	11th to 20th	Day	9% 15% 7% 21% 16% 9% 5% 4 4 3 7%	4453
	21st to end	Day	3 6% 6% 18% 9% 13% 10% 8% 8% 5% 14%	5124
February	1st to 10th	Day	7% 13% 5% 12% 10% 11% 9% 5% 5% 5% 18%	1817
	11th to 20th	Day	11% 16% 7% 14% 9% 8% 9% 4 4 4 14%	1843
	21st to end	Day	8% 13% 7% 15% 8% 9% 8% 4 4 5% 18%	1714
March	1st to 10th	Day	15% 17% 5% 11% 8% 6% 8% 5% 4 5% 16%	4639
	11th to 20th	Day	17% 18% 4 11% 7% 7% 6% 4 6% 6% 15%	5090
	21st to end	Day	20% 19% 6% 11% 7% 4 3 2 3 4 21%	5587
April	1st to 10th	Day	19% 17% 5% 12% 7% 4 4 3 5% 4 22%	2548
	11th to 20th	Day	17% 16% 5% 9% 6% 4 4 3 4 5% 28%	2702
	21st to end	Day	21% 15% 4 8% 5% 4 4 3 4 5% 28%	2730
May	1st to 10th	Day	23% 14% 3 9% 5% 4 4 3 4 5% 25%	7639
	11th to 20th	Day	21% 11% 3 8% 5% 5% 5% 4 5% 6% 28%	8476
	21st to end	Day	21% 11% 3 8% 5% 5% 5% 4 5% 6% 29%	9716
June	1st to 10th	Day	22% 10% 3 7% 5% 5% 4 3 6% 6% 28%	3150
	11th to 20th	Day	21% 8% 3 7% 6% 5% 4 4 6% 7% 30%	3150
	21st to end	Day	23% 9% 4 8% 6% 5% 5% 4 6% 6% 25%	3150
July	1st to 10th	Day	15% 7% 3 8% 5% 6% 6% 5% 7% 8% 31%	8880
	11th to 20th	Day	16% 7% 3 7% 6% 5% 6% 4 7% 8% 30%	8880
	21st to end	Day	12% 7% 3 8% 6% 6% 6% 5% 6% 8% 35%	9113
August	1st to 10th	Day	17% 7% 3 7% 5% 5% 5% 4 6% 8% 33%	6161
	11th to 20th	Day	18% 8% 3 10% 6% 6% 6% 5% 7% 6% 25%	5953
	21st to end	Day	16% 7% 3 7% 5% 5% 5% 4 6% 7% 35%	6594
September	1st to 10th	Day	18% 8% 2 7% 4 4 4 4 5% 8% 36%	2531
	11th to 20th	Day	17% 9% 3 7% 4 3 3 3 4 6% 42%	2310
	21st to end	Day	19% 9% 3 6% 4 4 4 3 5% 8% 36%	2310
October	1st to 10th	Day	18% 13% 3 8% 4 4 4 3 5% 5% 33%	2186
	11th to 20th	Day	22% 17% 3 7% 5% 4 4 3 5% 5% 25%	1985
	21st to end	Day	25% 20% 5% 7% 4 3 4 3 4 4 22%	1980
November	1st to 10th	Day	18% 20% 7% 9% 5% 5% 4 3 5% 4 20%	1777
	11th to 20th	Day	19% 20% 6% 14% 5% 5% 4 4 4 4 17%	1680
	21st to end	Day	19% 17% 5% 17% 9% 5% 4 3 4 3 14%	1600
December	1st to 10th	Day	14% 17% 5% 18% 13% 7% 5% 3 3 4 11%	2350
	11th to 20th	Day	17% 15% 4 17% 12% 6% 4 3 3 3 16%	2688
	21st to end	Day	14% 16% 4 14% 11% 10% 5% 2 3 3 17%	3553
January	1st to 10th	Night	12% 21% 7% 14% 10% 9% 9% 3 4 4 8%	8831
	11th to 20th	Night	9% 18% 7% 15% 11% 8% 6% 4 5% 4 13%	8438
	21st to end	Night	3 8% 5% 14% 9% 9% 10% 10% 7% 6% 18%	9057
February	1st to 10th	Night	7% 13% 4 13% 10% 9% 8% 5% 5% 5% 20%	2802
	11th to 20th	Night	11% 17% 5% 12% 8% 10% 7% 5% 4 4 17%	2663
	21st to end	Night	9% 13% 6% 11% 9% 8% 7% 4 5% 5% 23%	2088
March	1st to 10th	Night	15% 15% 4 10% 8% 6% 9% 4 3 5% 22%	5420
	11th to 20th	Night	19% 17% 5% 10% 7% 6% 5% 4 5% 6% 18%	5089
	21st to end	Night	21% 18% 4 11% 8% 4 3 2 3 4 21%	5587
April	1st to 10th	Night	21% 15% 4 8% 5% 5% 4 3 4 5% 25%	2067
	11th to 20th	Night	20% 13% 4 6% 4 5% 3 3 5% 6% 31%	1868
	21st to end	Night	21% 11% 2 8% 5% 4 4 4 5% 6% 30%	1890
May	1st to 10th	Night	25% 11% 3 7% 4 3 3 3 5% 6% 30%	5259
	11th to 20th	Night	21% 9% 3 7% 5% 4 4 4 5% 5% 32%	4450
	21st to end	Night	18% 10% 3 8% 4 5% 5% 3 5% 6% 33%	4491
June	1st to 10th	Night	19% 10% 3 7% 5% 4 4 4 5% 6% 32%	1470
	11th to 20th	Night	18% 8% 2 6% 4 5% 6% 4 6% 7% 35%	1470
	21st to end	Night	21% 9% 3 8% 5% 6% 5% 5% 5% 6% 28%	1470
July	1st to 10th	Night	14% 9% 3 7% 5% 5% 5% 4 6% 8% 34%	4110
	11th to 20th	Night	14% 8% 3 7% 4 6% 6% 4 6% 9% 33%	4110
	21st to end	Night	10% 6% 2 7% 5% 5% 6% 4 7% 8% 41%	4967
August	1st to 10th	Night	14% 7% 3 8% 5% 5% 5% 4 6% 7% 38%	3943
	11th to 20th	Night	13% 8% 3 9% 6% 6% 6% 6% 6% 8% 30%	4092
	21st to end	Night	15% 7% 3 7% 4 3 4 3 5% 7% 43%	4531
September	1st to 10th	Night	16% 7% 2 5% 3 4 4 4 5% 6% 43%	2085
	11th to 20th	Night	17% 8% 2 6% 5% 3 5% 3 5% 6% 40%	2310
	21st to end	Night	17% 7% 2 6% 3 4 4 3 5% 6% 44%	2310
October	1st to 10th	Night	18% 9% 2 6% 4 5% 4 3 5% 6% 37%	2433
	11th to 20th	Night	21% 13% 3 6% 5% 4 4 3 5% 6% 30%	2479
	21st to end	Night	20% 14% 4 9% 5% 4 4 4 5% 6% 26%	2860
November	1st to 10th	Night	19% 14% 5% 10% 6% 5% 4 3 4 5% 26%	2741
	11th to 20th	Night	18% 17% 5% 12% 5% 5% 4 4 5% 5% 21%	2940
	21st to end	Night	17% 16% 6% 16% 10% 5% 4 3 4 4 14%	3019
December	1st to 10th	Night	12% 15% 6% 17% 13% 6% 6% 4 4 4 14%	5060
	11th to 20th	Night	17% 16% 6% 13% 13% 7% 4 3 4 4 13%	5741
	21st to end	Night	15% 14% 6% 14% 9% 10% 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% 7% 4 1	4094
	11th to 20th	Day	79% 5% 7% 6% 2	4483
	21st to end	Day	64% 8% 10% 10% 8%	5124
February	1st to 10th	Day	67% 5% 10% 13% 6% 1	1817
	11th to 20th	Day	71% 5% 11% 9% 4	1851
	21st to end	Day	66% 6% 7% 16% 5% 1	1714
March	1st to 10th	Day	69% 6% 9% 11% 4 1	4643
	11th to 20th	Day	67% 8% 11% 11% 4	5090
	21st to end	Day	69% 3 5% 15% 7% 1	5587
April	1st to 10th	Day	65% 5% 9% 12% 8% 1	2548
	11th to 20th	Day	59% 5% 9% 18% 9% 1	2702
	21st to end	Day	59% 5% 8% 17% 10% 2	2730
May	1st to 10th	Day	60% 7% 10% 14% 9% 1	7651
	11th to 20th	Day	54% 8% 12% 16% 8% 1	8480
	21st to end	Day	54% 7% 9% 17% 12% 1	9717
June	1st to 10th	Day	56% 7% 9% 16% 11% 1	3150
	11th to 20th	Day	52% 7% 12% 17% 11% 1	3150
	21st to end	Day	57% 8% 12% 13% 9% 1	3150
July	1st to 10th	Day	47% 8% 13% 21% 11%	8805
	11th to 20th	Day	48% 8% 17% 21% 5%	8799
	21st to end	Day	44% 9% 16% 24% 6%	8912
August	1st to 10th	Day	47% 8% 18% 19% 7%	6147
	11th to 20th	Day	55% 10% 16% 16% 3	5992
	21st to end	Day	46% 8% 16% 22% 8%	6594
September	1st to 10th	Day	46% 7% 15% 22% 10%	2531
	11th to 20th	Day	43% 6% 16% 26% 9% 1	2310
	21st to end	Day	47% 6% 13% 24% 10% 1	2310
October	1st to 10th	Day	56% 7% 13% 19% 5% 1	3498
	11th to 20th	Day	60% 5% 12% 20% 3	3188
	21st to end	Day	59% 6% 13% 17% 6%	3180
November	1st to 10th	Day	67% 6% 10% 12% 5%	1777
	11th to 20th	Day	70% 6% 9% 10% 4	1680
	21st to end	Day	74% 6% 10% 7% 2	1600
December	1st to 10th	Day	76% 6% 9% 7% 1	2350
	11th to 20th	Day	70% 5% 9% 12% 4 1	2688
	21st to end	Day	72% 5% 9% 7% 5% 1	3553
January	1st to 10th	Night	81% 5% 7% 6%	8831
	11th to 20th	Night	72% 7% 8% 10% 3	8483
	21st to end	Night	58% 9% 10% 15% 7% 1	9057
February	1st to 10th	Night	64% 5% 10% 12% 7% 1	2802
	11th to 20th	Night	69% 5% 9% 12% 4	2666
	21st to end	Night	61% 6% 9% 16% 7%	2088
March	1st to 10th	Night	65% 5% 9% 13% 8%	5429
	11th to 20th	Night	66% 6% 13% 9% 5%	5090
	21st to end	Night	66% 5% 6% 13% 9% 1	5587
April	1st to 10th	Night	62% 4 9% 13% 10% 2	2067
	11th to 20th	Night	53% 5% 9% 19% 12% 1	1868
	21st to end	Night	53% 6% 9% 19% 12% 1	1890
May	1st to 10th	Night	55% 5% 11% 16% 12% 1	5265
	11th to 20th	Night	51% 7% 11% 21% 10% 1	4451
	21st to end	Night	49% 7% 11% 18% 14% 1	4492
June	1st to 10th	Night	51% 6% 12% 19% 11% 1	1470
	11th to 20th	Night	46% 8% 13% 18% 13% 2	1470
	21st to end	Night	55% 7% 12% 16% 9%	1470
July	1st to 10th	Night	47% 7% 15% 23% 7%	4075
	11th to 20th	Night	46% 9% 20% 23% 3	4068
	21st to end	Night	39% 9% 22% 23% 7%	4853
August	1st to 10th	Night	45% 8% 18% 22% 7%	3933
	11th to 20th	Night	48% 11% 22% 15% 4	4119
	21st to end	Night	41% 8% 16% 24% 11%	4531
September	1st to 10th	Night	42% 7% 15% 26% 10% 1	2085
	11th to 20th	Night	44% 7% 18% 21% 10% 1	2310
	21st to end	Night	41% 6% 13% 26% 14% 1	2310
October	1st to 10th	Night	49% 5% 12% 26% 7% 1	3901
	11th to 20th	Night	53% 5% 14% 25% 3	4015
	21st to end	Night	53% 7% 15% 17% 6%	4610
November	1st to 10th	Night	59% 7% 14% 14% 5%	2741
	11th to 20th	Night	66% 7% 11% 12% 4	2940
	21st to end	Night	73% 7% 10% 7% 2 1	3019
December	1st to 10th	Night	74% 6% 11% 8% 1	5060
	11th to 20th	Night	74% 6% 8% 8% 4	5742
	21st to end	Night	70% 6% 9% 10% 4 1	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	30% 26% 33% 8% 2 1	220
	11th to 20th	Day	28% 25% 28% 10% 8% 1	220
	21st to end	Day	19% 26% 34% 16% 5% 1	242
February	1st to 10th	Day	20% 29% 29% 14% 6% 3	357
	11th to 20th	Day	23% 28% 34% 11% 4	426
	21st to end	Day	25% 25% 32% 13% 4 1	438
March	1st to 10th	Day	28% 24% 32% 14% 2 1	540
	11th to 20th	Day	32% 22% 29% 9% 6% 1	540
	21st to end	Day	29% 26% 29% 12% 4 1	594
April	1st to 10th	Day	35% 24% 26% 10% 3 1	540
	11th to 20th	Day	33% 20% 30% 12% 5% 1	532
	21st to end	Day	30% 22% 32% 11% 4 1	540
May	1st to 10th	Day	34% 21% 29% 11% 4 1	543
	11th to 20th	Day	27% 20% 28% 17% 7%	736
	21st to end	Day	31% 20% 25% 17% 6% 1	845
June	1st to 10th	Day	27% 19% 28% 19% 5% 1	780
	11th to 20th	Day	28% 18% 26% 19% 8% 1	780
	21st to end	Day	28% 15% 31% 18% 6% 1	780
July	1st to 10th	Day	23% 17% 34% 19% 7% 1	770
	11th to 20th	Day	18% 16% 36% 22% 7% 1	768
	21st to end	Day	19% 16% 36% 22% 7% 1	663
August	1st to 10th	Day	19% 15% 36% 20% 7% 1	566
	11th to 20th	Day	18% 16% 31% 27% 8% 1	559
	21st to end	Day	21% 18% 30% 20% 8% 2	627
September	1st to 10th	Day	25% 14% 31% 19% 9% 2	570
	11th to 20th	Day	24% 18% 31% 18% 6% 3	570
	21st to end	Day	27% 19% 28% 13% 9% 4	570
October	1st to 10th	Day	25% 19% 30% 16% 7% 2	498
	11th to 20th	Day	37% 16% 24% 13% 8% 2	429
	21st to end	Day	35% 22% 22% 15% 5% 1	462
November	1st to 10th	Day	39% 22% 24% 10% 4	425
	11th to 20th	Day	33% 20% 26% 14% 6%	430
	21st to end	Day	37% 24% 25% 10% 2 1	350
December	1st to 10th	Day	29% 17% 33% 12% 8% 1	220
	11th to 20th	Day	33% 27% 27% 10% 4	220
	21st to end	Day	30% 30% 24% 12% 5%	242
January	1st to 10th	Night	25% 20% 34% 18% 3	950
	11th to 20th	Night	27% 23% 28% 16% 6%	878
	21st to end	Night	16% 23% 34% 21% 6%	924
February	1st to 10th	Night	17% 26% 31% 19% 6% 1	840
	11th to 20th	Night	25% 22% 31% 17% 5%	823
	21st to end	Night	20% 18% 39% 17% 5% 1	692
March	1st to 10th	Night	24% 19% 33% 20% 4	840
	11th to 20th	Night	28% 21% 28% 16% 6% 1	840
	21st to end	Night	27% 17% 28% 21% 6% 1	924
April	1st to 10th	Night	32% 19% 25% 19% 5%	781
	11th to 20th	Night	29% 15% 29% 19% 7%	624
	21st to end	Night	29% 15% 27% 22% 6% 1	630
May	1st to 10th	Night	29% 15% 27% 23% 6%	630
	11th to 20th	Night	24% 15% 28% 26% 7% 1	515
	21st to end	Night	25% 13% 31% 25% 6%	455
June	1st to 10th	Night	24% 7% 29% 33% 6%	420
	11th to 20th	Night	21% 10% 26% 31% 10% 1	420
	21st to end	Night	22% 11% 29% 29% 8% 1	420
July	1st to 10th	Night	16% 14% 31% 29% 10% 1	410
	11th to 20th	Night	14% 12% 31% 33% 10%	408
	21st to end	Night	15% 10% 29% 35% 10% 1	460
August	1st to 10th	Night	17% 7% 29% 31% 15% 1	539
	11th to 20th	Night	18% 6% 28% 36% 12% 1	622
	21st to end	Night	17% 11% 30% 28% 13% 2	693
September	1st to 10th	Night	21% 13% 31% 24% 10%	724
	11th to 20th	Night	23% 9% 29% 27% 11% 2	840
	21st to end	Night	23% 15% 26% 25% 12% 1	840
October	1st to 10th	Night	24% 17% 27% 23% 7% 1	840
	11th to 20th	Night	29% 16% 25% 21% 8% 1	813
	21st to end	Night	31% 20% 23% 21% 5%	880
November	1st to 10th	Night	31% 19% 28% 18% 4	859
	11th to 20th	Night	30% 21% 27% 16% 5% 1	950
	21st to end	Night	29% 20% 29% 16% 5%	950
December	1st to 10th	Night	28% 21% 29% 17% 5% 1	950
	11th to 20th	Night	33% 21% 27% 14% 5%	950
	21st to end	Night	27% 22% 26% 18% 6% 1	1045

Page generated at 2026-10-11 05:06:32. Version ac07

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