Mont-Joli
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mont-Joli 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% 10% 3 8% 6% 5% 5% 4 5% 7% 30%	101954
	Night	17% 13% 4 10% 7% 6% 5% 4 5% 6% 25%	97836
Transparency	Day	53% 9% 12% 17% 7% 1	105399
	Night	59% 8% 11% 15% 7% 1	102480
Seeing	Day	22% 14% 30% 24% 9% 1	16060
	Night	24% 14% 28% 25% 8% 1	23989

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% 17% 6% 16% 13% 14% 6% 3 3 3 6%	2207
	11th to 20th	Day	11% 13% 6% 17% 18% 8% 6% 5% 4 4 8%	2379
	21st to end	Day	6% 10% 4 11% 10% 11% 8% 5% 5% 6% 23%	2772
February	1st to 10th	Day	8% 12% 4 11% 10% 10% 8% 5% 5% 5% 21%	1619
	11th to 20th	Day	12% 15% 5% 14% 9% 7% 7% 4 4 4 20%	1663
	21st to end	Day	9% 13% 3 10% 9% 8% 6% 4 6% 7% 24%	1557
March	1st to 10th	Day	14% 11% 3 9% 6% 7% 7% 4 5% 8% 26%	3141
	11th to 20th	Day	20% 21% 4 8% 4 4 5% 4 5% 5% 19%	3480
	21st to end	Day	20% 18% 5% 10% 4 4 3 3 3 4 26%	3816
April	1st to 10th	Day	19% 13% 4 8% 5% 5% 4 3 5% 6% 27%	2317
	11th to 20th	Day	17% 11% 3 7% 5% 4 5% 3 5% 6% 34%	2442
	21st to end	Day	21% 11% 3 7% 4 3 4 3 4 5% 34%	2470
May	1st to 10th	Day	15% 9% 3 9% 4 4 4 4 5% 7% 34%	4106
	11th to 20th	Day	18% 8% 3 6% 5% 4 5% 4 5% 7% 33%	4602
	21st to end	Day	19% 9% 3 7% 4 4 5% 4 5% 7% 34%	5185
June	1st to 10th	Day	20% 8% 3 7% 5% 4 4 4 6% 7% 33%	2850
	11th to 20th	Day	17% 8% 2 6% 5% 4 4 4 6% 8% 36%	2850
	21st to end	Day	20% 7% 3 7% 5% 5% 5% 4 7% 8% 30%	2850
July	1st to 10th	Day	15% 7% 3 7% 5% 4 4 4 6% 8% 37%	4760
	11th to 20th	Day	13% 5% 2 7% 5% 5% 5% 5% 7% 8% 38%	4760
	21st to end	Day	11% 5% 2 6% 5% 5% 5% 4 7% 8% 44%	4890
August	1st to 10th	Day	12% 5% 2 6% 5% 4 6% 5% 8% 9% 38%	4243
	11th to 20th	Day	17% 6% 3 7% 5% 4 5% 4 6% 8% 35%	4045
	21st to end	Day	16% 5% 2 6% 5% 4 4 4 6% 7% 41%	4532
September	1st to 10th	Day	17% 7% 2 5% 3 4 4 3 5% 7% 42%	2296
	11th to 20th	Day	19% 7% 3 4 3 3 3 2 4 5% 46%	2090
	21st to end	Day	17% 7% 3 8% 5% 4 4 3 5% 6% 40%	2090
October	1st to 10th	Day	17% 9% 3 6% 4 4 4 4 5% 6% 36%	1983
	11th to 20th	Day	25% 10% 3 6% 5% 4 4 3 5% 7% 29%	1838
	21st to end	Day	23% 13% 3 8% 3 4 5% 4 5% 6% 27%	1881
November	1st to 10th	Day	19% 14% 4 10% 5% 4 5% 4 5% 5% 23%	1686
	11th to 20th	Day	21% 16% 6% 12% 5% 4 5% 3 5% 6% 18%	1600
	21st to end	Day	21% 18% 5% 14% 7% 4 4 3 4 5% 16%	1490
December	1st to 10th	Day	18% 17% 6% 15% 11% 7% 4 2 3 5% 10%	1365
	11th to 20th	Day	17% 17% 6% 15% 10% 8% 5% 2 3 3 15%	1668
	21st to end	Day	16% 14% 6% 13% 11% 6% 5% 4 4 4 17%	2431
January	1st to 10th	Night	11% 18% 8% 18% 15% 11% 5% 3 3 3 6%	4748
	11th to 20th	Night	12% 18% 7% 14% 10% 8% 5% 4 4 4 14%	4568
	21st to end	Night	6% 14% 6% 13% 8% 9% 7% 5% 5% 6% 22%	4884
February	1st to 10th	Night	9% 14% 6% 12% 9% 9% 6% 4 5% 4 21%	2561
	11th to 20th	Night	12% 16% 7% 12% 8% 6% 5% 3 5% 5% 19%	2403
	21st to end	Night	11% 15% 5% 11% 8% 8% 6% 3 4 5% 25%	1894
March	1st to 10th	Night	12% 12% 4 12% 6% 6% 7% 3 4 5% 28%	3698
	11th to 20th	Night	21% 23% 5% 11% 5% 5% 4 3 3 4 17%	3479
	21st to end	Night	23% 17% 4 9% 6% 3 3 3 4 5% 22%	3816
April	1st to 10th	Night	22% 14% 5% 10% 6% 4 4 3 3 3 27%	1860
	11th to 20th	Night	21% 11% 3 7% 4 3 5% 4 4 6% 32%	1688
	21st to end	Night	25% 9% 3 6% 4 3 4 3 4 5% 34%	1710
May	1st to 10th	Night	21% 9% 3 7% 5% 4 5% 4 5% 6% 31%	2834
	11th to 20th	Night	16% 9% 3 7% 5% 5% 4 4 7% 8% 32%	2329
	21st to end	Night	19% 8% 4 9% 5% 6% 5% 4 7% 7% 27%	2401
June	1st to 10th	Night	20% 9% 3 8% 5% 3 5% 5% 5% 7% 31%	1330
	11th to 20th	Night	19% 8% 2 7% 5% 4 4 4 6% 7% 33%	1330
	21st to end	Night	20% 9% 4 10% 5% 5% 4 3 5% 7% 28%	1330
July	1st to 10th	Night	16% 8% 3 7% 5% 5% 5% 4 6% 8% 33%	2210
	11th to 20th	Night	12% 7% 3 7% 5% 5% 6% 5% 7% 9% 33%	2210
	21st to end	Night	13% 6% 2 5% 4 4 5% 5% 6% 8% 40%	2663
August	1st to 10th	Night	18% 7% 3 7% 6% 5% 6% 4 7% 9% 29%	2654
	11th to 20th	Night	15% 6% 3 8% 6% 7% 6% 5% 6% 8% 30%	2782
	21st to end	Night	18% 6% 2 6% 4 3 4 3 5% 6% 40%	3124
September	1st to 10th	Night	18% 7% 2 6% 4 4 4 4 5% 7% 39%	1881
	11th to 20th	Night	21% 7% 3 7% 4 4 3 3 4 6% 39%	2090
	21st to end	Night	19% 6% 2 6% 4 3 3 2 4 6% 43%	2090
October	1st to 10th	Night	20% 7% 3 6% 4 4 4 3 5% 6% 38%	2196
	11th to 20th	Night	26% 11% 3 7% 4 4 4 3 5% 6% 28%	2338
	21st to end	Night	22% 13% 4 8% 4 4 5% 3 5% 6% 26%	2717
November	1st to 10th	Night	22% 13% 3 9% 6% 4 4 3 4 5% 26%	2611
	11th to 20th	Night	20% 19% 6% 9% 5% 4 3 3 3 4 22%	2800
	21st to end	Night	18% 20% 6% 14% 8% 5% 4 3 4 4 14%	2908
December	1st to 10th	Night	19% 18% 7% 16% 9% 6% 4 3 4 3 12%	2932
	11th to 20th	Night	16% 18% 6% 16% 11% 8% 5% 3 3 4 11%	3531
	21st to end	Night	16% 17% 5% 12% 7% 7% 5% 4 5% 5% 17%	5236

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	75% 16% 4 4 1	2208
	11th to 20th	Day	76% 10% 7% 5% 3	2379
	21st to end	Day	57% 15% 9% 12% 7%	2772
February	1st to 10th	Day	64% 8% 11% 11% 5% 1	1619
	11th to 20th	Day	67% 8% 10% 10% 5%	1671
	21st to end	Day	59% 9% 9% 17% 7% 1	1557
March	1st to 10th	Day	55% 11% 14% 15% 4 1	3144
	11th to 20th	Day	67% 9% 7% 12% 4	3480
	21st to end	Day	63% 5% 7% 17% 6% 2	3816
April	1st to 10th	Day	59% 6% 10% 13% 10% 1	2317
	11th to 20th	Day	51% 8% 10% 19% 10% 1	2442
	21st to end	Day	54% 6% 8% 18% 12% 2	2470
May	1st to 10th	Day	49% 11% 11% 17% 10% 1	4120
	11th to 20th	Day	47% 12% 12% 18% 10% 1	4606
	21st to end	Day	48% 9% 10% 22% 10% 1	5185
June	1st to 10th	Day	52% 9% 9% 16% 12% 2	2850
	11th to 20th	Day	47% 8% 12% 18% 13% 2	2850
	21st to end	Day	54% 10% 10% 15% 10% 1	2850
July	1st to 10th	Day	46% 8% 13% 25% 9%	4685
	11th to 20th	Day	42% 9% 21% 22% 6%	4679
	21st to end	Day	38% 10% 18% 25% 9%	4734
August	1st to 10th	Day	40% 10% 20% 23% 6%	4229
	11th to 20th	Day	46% 11% 21% 18% 4	4084
	21st to end	Day	42% 9% 17% 21% 11%	4532
September	1st to 10th	Day	43% 8% 15% 24% 10%	2296
	11th to 20th	Day	42% 7% 14% 26% 10%	2090
	21st to end	Day	46% 8% 12% 24% 9%	2090
October	1st to 10th	Day	52% 8% 13% 20% 6% 1	3295
	11th to 20th	Day	55% 6% 13% 23% 3	3028
	21st to end	Day	53% 8% 15% 17% 6%	3081
November	1st to 10th	Day	62% 8% 12% 13% 5%	1686
	11th to 20th	Day	68% 9% 8% 11% 3	1600
	21st to end	Day	72% 6% 10% 9% 2	1490
December	1st to 10th	Day	79% 8% 6% 5% 1	1365
	11th to 20th	Day	75% 8% 6% 8% 3	1668
	21st to end	Day	68% 9% 11% 7% 4	2431
January	1st to 10th	Night	80% 10% 5% 4 1	4748
	11th to 20th	Night	70% 9% 9% 8% 4	4568
	21st to end	Night	59% 9% 11% 13% 6% 1	4884
February	1st to 10th	Night	64% 9% 8% 10% 7% 1	2561
	11th to 20th	Night	67% 7% 9% 11% 5%	2406
	21st to end	Night	60% 8% 8% 16% 7% 1	1894
March	1st to 10th	Night	58% 8% 11% 16% 7%	3707
	11th to 20th	Night	71% 5% 9% 10% 5%	3480
	21st to end	Night	65% 4 7% 14% 8% 1	3816
April	1st to 10th	Night	64% 4 8% 11% 12% 1	1860
	11th to 20th	Night	52% 6% 8% 17% 15% 1	1688
	21st to end	Night	52% 6% 8% 18% 14% 1	1710
May	1st to 10th	Night	50% 8% 16% 13% 12% 1	2840
	11th to 20th	Night	47% 8% 12% 22% 11% 1	2330
	21st to end	Night	52% 8% 11% 19% 9% 1	2402
June	1st to 10th	Night	52% 8% 11% 17% 11% 2	1330
	11th to 20th	Night	48% 7% 12% 17% 13% 2	1330
	21st to end	Night	55% 8% 10% 16% 11%	1330
July	1st to 10th	Night	47% 8% 13% 25% 7%	2175
	11th to 20th	Night	44% 10% 21% 21% 5%	2168
	21st to end	Night	40% 9% 22% 19% 10%	2578
August	1st to 10th	Night	48% 10% 16% 21% 5%	2644
	11th to 20th	Night	48% 11% 22% 13% 6%	2809
	21st to end	Night	44% 9% 12% 22% 14%	3124
September	1st to 10th	Night	43% 7% 14% 25% 10% 1	1881
	11th to 20th	Night	48% 6% 15% 22% 9%	2090
	21st to end	Night	44% 6% 13% 24% 13% 1	2090
October	1st to 10th	Night	48% 6% 12% 26% 7%	3664
	11th to 20th	Night	56% 6% 12% 23% 3	3887
	21st to end	Night	55% 9% 14% 17% 4 1	4467
November	1st to 10th	Night	61% 6% 14% 14% 5% 1	2611
	11th to 20th	Night	67% 6% 10% 12% 4	2800
	21st to end	Night	74% 8% 9% 6% 3 1	2908
December	1st to 10th	Night	78% 6% 8% 7% 2	2932
	11th to 20th	Night	79% 5% 6% 7% 3	3532
	21st to end	Night	65% 9% 13% 7% 5% 1	5236

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	23% 21% 33% 19% 3 1	180
	11th to 20th	Day	22% 26% 31% 16% 5% 1	180
	21st to end	Day	14% 24% 33% 20% 8% 1	198
February	1st to 10th	Day	16% 20% 36% 21% 6% 1	279
	11th to 20th	Day	16% 23% 38% 19% 5%	366
	21st to end	Day	17% 21% 37% 18% 7% 1	377
March	1st to 10th	Day	21% 17% 35% 22% 4	460
	11th to 20th	Day	24% 18% 28% 20% 8% 1	460
	21st to end	Day	25% 21% 28% 20% 5% 1	506
April	1st to 10th	Day	26% 19% 31% 18% 5% 1	460
	11th to 20th	Day	22% 15% 35% 20% 6% 1	452
	21st to end	Day	26% 17% 31% 19% 5% 2	460
May	1st to 10th	Day	27% 15% 29% 21% 7% 1	463
	11th to 20th	Day	23% 11% 27% 27% 11% 1	645
	21st to end	Day	25% 15% 31% 20% 8% 1	735
June	1st to 10th	Day	25% 8% 33% 26% 7% 1	680
	11th to 20th	Day	23% 10% 27% 27% 12% 1	680
	21st to end	Day	21% 9% 26% 33% 10% 1	680
July	1st to 10th	Day	18% 6% 32% 32% 10% 1	670
	11th to 20th	Day	17% 7% 26% 37% 12% 1	668
	21st to end	Day	15% 6% 27% 37% 13% 1	582
August	1st to 10th	Day	16% 8% 27% 32% 14% 2	486
	11th to 20th	Day	18% 6% 25% 34% 15% 1	479
	21st to end	Day	19% 8% 25% 29% 15% 3	539
September	1st to 10th	Day	19% 12% 28% 28% 12% 2	490
	11th to 20th	Day	23% 10% 29% 25% 10% 2	490
	21st to end	Day	17% 16% 32% 21% 11% 3	490
October	1st to 10th	Day	20% 15% 29% 24% 11% 1	433
	11th to 20th	Day	34% 13% 26% 16% 10% 1	390
	21st to end	Day	33% 17% 27% 15% 7%	429
November	1st to 10th	Day	28% 24% 29% 15% 4	395
	11th to 20th	Day	31% 18% 29% 17% 6% 1	400
	21st to end	Day	30% 23% 29% 15% 3 1	290
December	1st to 10th	Day	26% 15% 36% 13% 9% 1	190
	11th to 20th	Day	26% 28% 32% 10% 4	180
	21st to end	Day	22% 25% 35% 14% 3	198
January	1st to 10th	Night	23% 19% 35% 19% 3	850
	11th to 20th	Night	25% 20% 31% 20% 4	796
	21st to end	Night	15% 18% 33% 27% 7%	836
February	1st to 10th	Night	14% 20% 36% 22% 7% 1	760
	11th to 20th	Night	23% 15% 34% 21% 6% 1	743
	21st to end	Night	17% 16% 34% 25% 7% 1	628
March	1st to 10th	Night	21% 15% 32% 25% 7% 1	760
	11th to 20th	Night	25% 16% 31% 20% 8% 1	760
	21st to end	Night	25% 15% 28% 24% 7% 1	836
April	1st to 10th	Night	29% 16% 28% 21% 7%	710
	11th to 20th	Night	28% 12% 26% 24% 10% 1	564
	21st to end	Night	28% 13% 26% 24% 8% 1	570
May	1st to 10th	Night	29% 9% 24% 29% 7% 1	570
	11th to 20th	Night	22% 8% 25% 30% 14%	435
	21st to end	Night	26% 9% 29% 27% 8% 1	411
June	1st to 10th	Night	23% 4 26% 38% 8%	380
	11th to 20th	Night	22% 7% 21% 34% 15% 1	380
	21st to end	Night	21% 5% 30% 34% 9% 1	380
July	1st to 10th	Night	18% 6% 29% 36% 9% 2	370
	11th to 20th	Night	15% 5% 25% 41% 13% 1	368
	21st to end	Night	18% 4 22% 38% 16% 1	416
August	1st to 10th	Night	19% 6% 24% 30% 19% 2	461
	11th to 20th	Night	18% 4 21% 37% 19% 1	562
	21st to end	Night	18% 6% 23% 34% 16% 3	627
September	1st to 10th	Night	22% 7% 27% 32% 12%	660
	11th to 20th	Night	23% 8% 25% 29% 12% 2	760
	21st to end	Night	21% 10% 26% 31% 11% 1	760
October	1st to 10th	Night	26% 11% 26% 27% 9% 1	760
	11th to 20th	Night	33% 10% 24% 22% 11% 1	760
	21st to end	Night	30% 17% 25% 21% 7%	836
November	1st to 10th	Night	30% 18% 27% 19% 5%	817
	11th to 20th	Night	28% 20% 27% 19% 5% 1	900
	21st to end	Night	28% 18% 31% 17% 5% 1	900
December	1st to 10th	Night	28% 17% 30% 18% 6% 1	878
	11th to 20th	Night	26% 22% 29% 18% 4 1	850
	21st to end	Night	26% 21% 24% 22% 5% 2	935

Page generated at 2024-12-03 06:45:08. Version ac07

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