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 2025-06-10.

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%	119325
	Night	15% 13% 4 11% 7% 6% 5% 4 5% 5% 24%	119029
Transparency	Day	59% 7% 11% 15% 7% 1	122811
	Night	60% 7% 12% 15% 7% 1	123705
Seeing	Day	27% 20% 30% 16% 6% 1	16732
	Night	25% 17% 29% 21% 7% 1	24725

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% 24% 7% 17% 9% 11% 5% 2 3 3 5%	3157
	11th to 20th	Day	8% 12% 7% 22% 18% 10% 5% 3 4 3 7%	3412
	21st to end	Day	4 7% 5% 16% 8% 12% 11% 8% 8% 5% 16%	3960
February	1st to 10th	Day	8% 14% 5% 12% 10% 12% 9% 5% 5% 5% 17%	1730
	11th to 20th	Day	11% 16% 7% 14% 9% 8% 9% 4 4 4 14%	1753
	21st to end	Day	8% 14% 7% 14% 8% 9% 8% 4 4 5% 18%	1635
March	1st to 10th	Day	15% 17% 5% 11% 8% 6% 7% 4 4 4 16%	4538
	11th to 20th	Day	16% 18% 4 11% 7% 7% 6% 4 6% 6% 15%	4980
	21st to end	Day	20% 19% 6% 11% 6% 4 3 2 3 4 21%	5466
April	1st to 10th	Day	19% 17% 5% 12% 7% 4 4 3 5% 4 22%	2426
	11th to 20th	Day	16% 16% 5% 9% 6% 4 4 3 5% 5% 28%	2572
	21st to end	Day	22% 15% 4 8% 5% 4 4 3 3 5% 28%	2600
May	1st to 10th	Day	21% 15% 4 9% 6% 4 4 3 4 5% 26%	5886
	11th to 20th	Day	23% 11% 4 8% 5% 5% 5% 4 5% 6% 27%	6516
	21st to end	Day	20% 10% 3 7% 5% 5% 5% 4 5% 7% 31%	7451
June	1st to 10th	Day	23% 10% 3 7% 5% 5% 4 3 6% 6% 28%	2985
	11th to 20th	Day	20% 8% 2 7% 5% 6% 4 4 6% 7% 32%	2850
	21st to end	Day	24% 8% 4 8% 6% 5% 5% 4 6% 6% 25%	2850
July	1st to 10th	Day	18% 9% 3 8% 5% 5% 6% 5% 6% 6% 30%	4760
	11th to 20th	Day	15% 7% 3 7% 6% 6% 6% 4 6% 8% 33%	4760
	21st to end	Day	13% 8% 2 6% 5% 5% 5% 4 6% 8% 37%	4879
August	1st to 10th	Day	16% 6% 3 7% 5% 5% 5% 5% 6% 9% 33%	4206
	11th to 20th	Day	19% 7% 3 9% 6% 6% 5% 5% 7% 7% 25%	4045
	21st to end	Day	18% 7% 3 8% 5% 4 4 3 5% 7% 36%	4532
September	1st to 10th	Day	19% 8% 2 7% 4 4 4 4 5% 8% 36%	2291
	11th to 20th	Day	18% 9% 3 6% 3 3 3 2 4 6% 43%	2090
	21st to end	Day	20% 9% 3 6% 4 4 4 3 4 7% 36%	2090
October	1st to 10th	Day	18% 13% 3 8% 4 5% 4 3 5% 5% 33%	1978
	11th to 20th	Day	23% 16% 3 7% 5% 3 4 3 5% 5% 25%	1857
	21st to end	Day	25% 20% 5% 7% 4 3 4 3 4 4 23%	1881
November	1st to 10th	Day	19% 19% 7% 9% 5% 5% 4 4 4 4 21%	1691
	11th to 20th	Day	19% 20% 5% 14% 5% 5% 4 3 4 4 18%	1600
	21st to end	Day	19% 17% 5% 16% 9% 4 4 3 4 3 15%	1524
December	1st to 10th	Day	15% 17% 5% 18% 13% 7% 5% 2 3 4 11%	2280
	11th to 20th	Day	17% 15% 4 16% 12% 6% 4 3 3 3 16%	2618
	21st to end	Day	15% 16% 4 14% 11% 10% 5% 2 3 3 17%	3476
January	1st to 10th	Night	12% 25% 8% 15% 11% 10% 5% 3 4 3 6%	6808
	11th to 20th	Night	9% 17% 7% 17% 13% 8% 6% 4 4 4 12%	6476
	21st to end	Night	4 9% 5% 13% 7% 8% 11% 8% 8% 7% 22%	6996
February	1st to 10th	Night	8% 14% 4 13% 10% 9% 8% 5% 5% 5% 19%	2669
	11th to 20th	Night	11% 16% 5% 12% 8% 10% 8% 5% 4 4 17%	2533
	21st to end	Night	10% 14% 6% 10% 9% 8% 7% 4 5% 5% 23%	1992
March	1st to 10th	Night	15% 15% 4 10% 8% 6% 9% 4 3 5% 22%	5301
	11th to 20th	Night	18% 17% 5% 10% 7% 6% 5% 4 5% 6% 18%	4979
	21st to end	Night	21% 18% 4 11% 8% 4 3 2 3 4 22%	5466
April	1st to 10th	Night	21% 15% 4 8% 5% 5% 4 3 4 5% 25%	1969
	11th to 20th	Night	20% 13% 3 6% 4 5% 4 3 5% 6% 32%	1778
	21st to end	Night	22% 11% 2 8% 5% 4 4 3 5% 6% 30%	1800
May	1st to 10th	Night	21% 10% 3 7% 5% 4 4 3 5% 6% 32%	4054
	11th to 20th	Night	22% 10% 3 7% 4 4 3 4 5% 6% 31%	3422
	21st to end	Night	16% 7% 3 7% 5% 5% 5% 4 6% 7% 35%	3446
June	1st to 10th	Night	19% 10% 3 7% 5% 4 4 4 5% 6% 33%	1399
	11th to 20th	Night	18% 7% 2 5% 4 5% 6% 4 6% 7% 37%	1330
	21st to end	Night	22% 8% 2 8% 5% 5% 5% 5% 5% 6% 29%	1330
July	1st to 10th	Night	14% 9% 3 7% 6% 4 6% 4 6% 8% 33%	2210
	11th to 20th	Night	14% 9% 3 7% 4 6% 6% 4 6% 9% 34%	2210
	21st to end	Night	12% 6% 2 5% 4 4 5% 3 7% 9% 43%	2673
August	1st to 10th	Night	15% 6% 2 8% 5% 5% 5% 4 6% 8% 35%	2693
	11th to 20th	Night	14% 7% 3 8% 5% 6% 6% 6% 7% 8% 30%	2782
	21st to end	Night	17% 7% 3 7% 4 4 4 3 5% 6% 42%	3124
September	1st to 10th	Night	17% 7% 2 5% 3 4 4 4 5% 6% 43%	1886
	11th to 20th	Night	18% 8% 2 6% 5% 3 4 3 5% 6% 40%	2090
	21st to end	Night	18% 8% 2 6% 4 4 4 3 4 6% 43%	2090
October	1st to 10th	Night	19% 8% 3 6% 4 5% 4 3 5% 6% 38%	2201
	11th to 20th	Night	21% 13% 3 6% 5% 4 4 3 5% 5% 30%	2320
	21st to end	Night	20% 14% 4 8% 4 4 4 4 5% 6% 26%	2717
November	1st to 10th	Night	18% 14% 5% 10% 6% 5% 3 3 4 5% 26%	2607
	11th to 20th	Night	19% 17% 4 12% 5% 4 4 4 5% 5% 21%	2800
	21st to end	Night	17% 17% 6% 16% 10% 5% 4 3 4 4 14%	2875
December	1st to 10th	Night	13% 15% 6% 17% 13% 6% 5% 3 4 4 14%	4910
	11th to 20th	Night	17% 16% 6% 13% 13% 7% 4 3 4 4 13%	5591
	21st to end	Night	15% 14% 6% 14% 9% 10% 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	84% 5% 8% 3 1	3158
	11th to 20th	Day	80% 5% 8% 6% 2	3442
	21st to end	Day	61% 8% 11% 11% 9%	3960
February	1st to 10th	Day	67% 5% 10% 12% 6% 1	1730
	11th to 20th	Day	71% 5% 11% 9% 4	1761
	21st to end	Day	66% 6% 7% 16% 5% 1	1635
March	1st to 10th	Day	69% 6% 9% 11% 4 1	4542
	11th to 20th	Day	67% 8% 11% 11% 4	4980
	21st to end	Day	68% 3 5% 15% 7% 1	5466
April	1st to 10th	Day	65% 5% 9% 12% 8% 1	2426
	11th to 20th	Day	58% 5% 9% 18% 9% 1	2572
	21st to end	Day	59% 5% 8% 17% 10% 2	2600
May	1st to 10th	Day	60% 7% 9% 15% 9% 1	5897
	11th to 20th	Day	56% 9% 13% 14% 7% 2	6520
	21st to end	Day	50% 8% 11% 21% 9%	7451
June	1st to 10th	Day	56% 7% 9% 15% 11% 1	2985
	11th to 20th	Day	51% 7% 12% 17% 11% 2	2850
	21st to end	Day	57% 8% 12% 14% 9%	2850
July	1st to 10th	Day	52% 8% 12% 19% 10%	4685
	11th to 20th	Day	47% 8% 17% 22% 6%	4679
	21st to end	Day	43% 9% 17% 23% 8%	4723
August	1st to 10th	Day	47% 9% 18% 19% 7%	4192
	11th to 20th	Day	54% 11% 17% 15% 4	4084
	21st to end	Day	48% 7% 16% 19% 10%	4532
September	1st to 10th	Day	46% 7% 14% 22% 10%	2291
	11th to 20th	Day	43% 6% 15% 26% 10%	2090
	21st to end	Day	47% 7% 13% 23% 9%	2090
October	1st to 10th	Day	56% 6% 13% 19% 5% 1	3290
	11th to 20th	Day	60% 5% 12% 20% 3	3060
	21st to end	Day	58% 6% 13% 17% 6%	3081
November	1st to 10th	Day	67% 6% 9% 12% 5%	1691
	11th to 20th	Day	70% 6% 10% 10% 5%	1600
	21st to end	Day	73% 6% 11% 8% 2	1524
December	1st to 10th	Day	77% 6% 9% 7% 1	2280
	11th to 20th	Day	69% 5% 9% 12% 4 1	2618
	21st to end	Day	72% 5% 9% 7% 5% 1	3476
January	1st to 10th	Night	84% 5% 6% 5% 1	6808
	11th to 20th	Night	73% 7% 8% 9% 3	6521
	21st to end	Night	55% 9% 11% 17% 7% 1	6996
February	1st to 10th	Night	65% 5% 10% 12% 7% 1	2669
	11th to 20th	Night	69% 5% 9% 12% 4	2536
	21st to end	Night	61% 6% 9% 16% 6% 1	1992
March	1st to 10th	Night	65% 5% 9% 13% 8%	5310
	11th to 20th	Night	66% 6% 13% 9% 5%	4980
	21st to end	Night	66% 5% 6% 13% 9% 1	5466
April	1st to 10th	Night	62% 4 8% 13% 11% 2	1969
	11th to 20th	Night	53% 5% 10% 19% 13% 1	1778
	21st to end	Night	54% 6% 9% 18% 12% 1	1800
May	1st to 10th	Night	52% 6% 12% 14% 14% 2	4060
	11th to 20th	Night	51% 7% 12% 20% 8% 1	3423
	21st to end	Night	44% 9% 13% 22% 11%	3447
June	1st to 10th	Night	51% 5% 12% 19% 11% 2	1399
	11th to 20th	Night	44% 8% 13% 18% 14% 2	1330
	21st to end	Night	55% 7% 11% 17% 9%	1330
July	1st to 10th	Night	47% 8% 15% 23% 7%	2175
	11th to 20th	Night	46% 8% 22% 19% 4 1	2168
	21st to end	Night	37% 9% 23% 21% 9%	2588
August	1st to 10th	Night	46% 9% 18% 22% 6%	2683
	11th to 20th	Night	47% 12% 22% 14% 5%	2809
	21st to end	Night	43% 7% 15% 22% 13%	3124
September	1st to 10th	Night	41% 7% 15% 26% 11% 1	1886
	11th to 20th	Night	44% 7% 18% 21% 9%	2090
	21st to end	Night	42% 7% 13% 25% 12% 1	2090
October	1st to 10th	Night	50% 5% 11% 26% 7% 1	3669
	11th to 20th	Night	54% 5% 14% 25% 3	3856
	21st to end	Night	53% 7% 16% 17% 6%	4467
November	1st to 10th	Night	58% 7% 14% 15% 5%	2607
	11th to 20th	Night	65% 7% 11% 12% 5%	2800
	21st to end	Night	74% 7% 10% 7% 2 1	2875
December	1st to 10th	Night	74% 6% 11% 8% 1	4910
	11th to 20th	Night	74% 6% 8% 8% 4	5592
	21st to end	Night	70% 6% 9% 10% 4 1	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	32% 27% 33% 7% 2 1	200
	11th to 20th	Day	28% 24% 29% 10% 9% 1	200
	21st to end	Day	19% 26% 35% 15% 5% 1	220
February	1st to 10th	Day	21% 30% 30% 13% 6% 1	330
	11th to 20th	Day	24% 28% 33% 11% 4	396
	21st to end	Day	26% 26% 31% 12% 4 1	407
March	1st to 10th	Day	26% 24% 33% 15% 2 1	500
	11th to 20th	Day	30% 23% 29% 10% 7% 1	500
	21st to end	Day	30% 25% 29% 12% 4 1	550
April	1st to 10th	Day	35% 24% 26% 10% 3 1	500
	11th to 20th	Day	32% 20% 30% 13% 5% 1	492
	21st to end	Day	31% 22% 32% 10% 4 1	500
May	1st to 10th	Day	34% 21% 29% 12% 4 1	503
	11th to 20th	Day	28% 19% 28% 18% 7%	688
	21st to end	Day	30% 21% 25% 17% 6% 1	790
June	1st to 10th	Day	28% 19% 28% 19% 5% 2	725
	11th to 20th	Day	27% 18% 26% 20% 8% 1	680
	21st to end	Day	28% 14% 31% 20% 5% 1	680
July	1st to 10th	Day	23% 16% 34% 19% 7% 1	670
	11th to 20th	Day	18% 14% 36% 24% 7% 1	668
	21st to end	Day	19% 14% 37% 22% 8% 1	571
August	1st to 10th	Day	21% 17% 34% 20% 7% 1	486
	11th to 20th	Day	19% 16% 31% 27% 7% 1	479
	21st to end	Day	22% 16% 30% 20% 9% 3	539
September	1st to 10th	Day	25% 13% 31% 19% 9% 2	490
	11th to 20th	Day	24% 16% 32% 18% 7% 2	490
	21st to end	Day	27% 20% 29% 12% 8% 3	490
October	1st to 10th	Day	25% 18% 30% 17% 8% 2	430
	11th to 20th	Day	37% 17% 24% 13% 7% 2	390
	21st to end	Day	35% 22% 22% 15% 5% 1	429
November	1st to 10th	Day	37% 22% 25% 10% 5%	395
	11th to 20th	Day	33% 21% 25% 15% 6% 1	400
	21st to end	Day	38% 24% 25% 10% 2 1	324
December	1st to 10th	Day	30% 16% 33% 13% 8% 1	200
	11th to 20th	Day	33% 28% 26% 10% 4	200
	21st to end	Day	31% 29% 24% 12% 4	220
January	1st to 10th	Night	25% 20% 34% 18% 3	900
	11th to 20th	Night	27% 23% 27% 16% 6%	835
	21st to end	Night	17% 23% 34% 21% 5%	880
February	1st to 10th	Night	18% 27% 31% 18% 6% 1	800
	11th to 20th	Night	25% 22% 31% 17% 4	783
	21st to end	Night	21% 19% 38% 17% 5% 1	660
March	1st to 10th	Night	23% 19% 34% 20% 4	800
	11th to 20th	Night	27% 21% 29% 16% 7% 1	800
	21st to end	Night	27% 17% 28% 21% 6% 1	880
April	1st to 10th	Night	31% 19% 25% 19% 5%	744
	11th to 20th	Night	29% 15% 30% 19% 7% 1	594
	21st to end	Night	30% 15% 27% 22% 6% 1	600
May	1st to 10th	Night	28% 16% 27% 24% 6%	600
	11th to 20th	Night	24% 14% 28% 27% 7% 1	490
	21st to end	Night	23% 13% 31% 25% 6%	433
June	1st to 10th	Night	25% 7% 29% 33% 6%	400
	11th to 20th	Night	21% 9% 28% 31% 11% 1	380
	21st to end	Night	23% 10% 30% 28% 8% 1	380
July	1st to 10th	Night	15% 14% 32% 28% 9% 1	370
	11th to 20th	Night	14% 11% 30% 35% 10%	368
	21st to end	Night	16% 10% 28% 36% 10% 1	416
August	1st to 10th	Night	18% 7% 29% 31% 14% 1	487
	11th to 20th	Night	18% 7% 28% 34% 12% 1	562
	21st to end	Night	17% 11% 29% 28% 13% 2	627
September	1st to 10th	Night	21% 13% 32% 23% 10%	655
	11th to 20th	Night	23% 8% 29% 27% 11% 2	760
	21st to end	Night	23% 15% 28% 24% 11% 1	760
October	1st to 10th	Night	24% 16% 27% 23% 8% 1	760
	11th to 20th	Night	30% 17% 24% 21% 8% 1	760
	21st to end	Night	31% 20% 23% 21% 5%	836
November	1st to 10th	Night	31% 19% 28% 18% 4	815
	11th to 20th	Night	30% 21% 27% 16% 4 1	900
	21st to end	Night	30% 19% 30% 16% 4	900
December	1st to 10th	Night	28% 21% 28% 17% 5% 1	900
	11th to 20th	Night	33% 21% 27% 14% 5%	900
	21st to end	Night	28% 22% 25% 18% 6% 1	990

Page generated at 2025-06-07 10:28:14. Version ac07

Copyright © 2025 Attilla Danko.