Rondeau Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rondeau Provincial Park clear sky chart from 2005-11-06 to 2025-02-21.

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	14% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	109038
	Night	15% 10% 4 8% 5% 5% 4 4 5% 7% 33%	109432
Transparency	Day	47% 8% 13% 21% 11% 1	112684
	Night	50% 7% 11% 19% 12% 1	113927
Seeing	Day	16% 7% 21% 31% 20% 5%	15365
	Night	20% 8% 24% 29% 16% 3	24755

By Month

Percentage Cloud Cover SE (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	13% 15% 7% 18% 6% 5% 4 4 4 5% 19%	3770
	11th to 20th	Day	14% 21% 8% 14% 8% 9% 5% 3 4 3 11%	4060
	21st to end	Day	20% 14% 6% 13% 6% 6% 6% 4 5% 4 15%	4466
February	1st to 10th	Day	15% 16% 4 10% 8% 5% 5% 3 5% 5% 23%	1800
	11th to 20th	Day	15% 10% 4 11% 8% 6% 6% 4 5% 5% 26%	1803
	21st to end	Day	17% 11% 4 10% 6% 5% 5% 4 6% 6% 28%	1570
March	1st to 10th	Day	20% 10% 4 9% 6% 5% 5% 4 4 5% 28%	3312
	11th to 20th	Day	12% 10% 4 9% 6% 5% 5% 4 6% 7% 33%	3480
	21st to end	Day	17% 8% 3 8% 5% 5% 5% 4 5% 6% 34%	3815
April	1st to 10th	Day	14% 9% 3 7% 5% 5% 5% 3 6% 8% 33%	2133
	11th to 20th	Day	17% 8% 3 6% 4 4 5% 4 6% 7% 35%	2442
	21st to end	Day	17% 8% 3 8% 5% 5% 5% 3 6% 6% 35%	2470
May	1st to 10th	Day	16% 8% 3 8% 4 5% 6% 4 5% 7% 35%	4082
	11th to 20th	Day	17% 9% 3 7% 5% 5% 6% 4 6% 9% 30%	4081
	21st to end	Day	9% 5% 2 6% 5% 4 4 4 6% 8% 46%	4635
June	1st to 10th	Day	10% 6% 2 6% 5% 4 5% 5% 8% 9% 40%	2660
	11th to 20th	Day	8% 4 3 6% 5% 4 5% 5% 7% 10% 43%	2829
	21st to end	Day	10% 5% 2 6% 4 4 4 4 7% 11% 44%	2850
July	1st to 10th	Day	9% 5% 2 6% 5% 4 5% 4 6% 9% 46%	4547
	11th to 20th	Day	8% 5% 1 5% 4 3 5% 3 6% 9% 51%	4200
	21st to end	Day	7% 4 2 5% 5% 5% 5% 5% 6% 9% 46%	4466
August	1st to 10th	Day	13% 5% 2 5% 4 3 4 4 6% 9% 44%	4104
	11th to 20th	Day	7% 5% 2 6% 4 4 6% 5% 7% 10% 42%	4044
	21st to end	Day	9% 4 2 6% 4 5% 6% 4 7% 9% 44%	4505
September	1st to 10th	Day	10% 6% 2 5% 4 4 5% 4 6% 7% 46%	2174
	11th to 20th	Day	9% 4 2 4 4 4 5% 4 6% 10% 48%	2090
	21st to end	Day	17% 6% 3 6% 4 5% 5% 3 6% 7% 40%	2090
October	1st to 10th	Day	13% 6% 2 7% 5% 5% 5% 3 6% 7% 43%	1971
	11th to 20th	Day	17% 7% 3 8% 5% 5% 5% 4 6% 7% 34%	1900
	21st to end	Day	21% 9% 3 8% 5% 4 5% 4 6% 7% 29%	2038
November	1st to 10th	Day	12% 10% 3 7% 6% 5% 5% 4 6% 7% 36%	1762
	11th to 20th	Day	16% 12% 3 8% 6% 4 5% 4 6% 6% 30%	1732
	21st to end	Day	19% 15% 5% 11% 5% 3 5% 4 5% 7% 21%	1600
December	1st to 10th	Day	18% 14% 5% 11% 5% 5% 5% 4 5% 7% 21%	2600
	11th to 20th	Day	22% 18% 5% 10% 5% 4 4 4 5% 6% 15%	2990
	21st to end	Day	26% 18% 7% 11% 5% 5% 5% 3 4 5% 12%	3967
January	1st to 10th	Night	14% 13% 6% 12% 5% 6% 5% 3 5% 6% 25%	6142
	11th to 20th	Night	12% 18% 8% 14% 8% 6% 8% 4 4 4 14%	5900
	21st to end	Night	21% 15% 6% 9% 6% 4 4 4 5% 5% 22%	6490
February	1st to 10th	Night	17% 14% 5% 11% 6% 5% 4 3 5% 5% 24%	2600
	11th to 20th	Night	16% 13% 4 9% 6% 5% 4 4 6% 6% 26%	2479
	21st to end	Night	20% 11% 3 8% 5% 5% 5% 5% 5% 5% 27%	1885
March	1st to 10th	Night	19% 12% 3 7% 6% 4 4 3 4 6% 32%	3541
	11th to 20th	Night	10% 8% 3 7% 5% 4 5% 4 6% 7% 40%	3480
	21st to end	Night	16% 10% 3 7% 4 4 4 3 5% 5% 39%	3817
April	1st to 10th	Night	16% 11% 3 7% 5% 5% 3 3 5% 7% 35%	2054
	11th to 20th	Night	18% 7% 3 6% 5% 5% 4 3 5% 8% 36%	1692
	21st to end	Night	16% 8% 3 7% 5% 4 5% 4 5% 7% 37%	1710
May	1st to 10th	Night	18% 8% 3 8% 4 4 4 4 6% 7% 34%	2813
	11th to 20th	Night	12% 9% 3 9% 5% 5% 5% 5% 6% 7% 33%	2812
	21st to end	Night	10% 5% 2 5% 3 5% 5% 4 5% 8% 49%	2902
June	1st to 10th	Night	11% 5% 3 6% 5% 5% 4 3 6% 8% 45%	1520
	11th to 20th	Night	10% 5% 2 5% 5% 4 4 4 8% 8% 44%	1344
	21st to end	Night	9% 6% 2 5% 5% 5% 5% 4 5% 8% 47%	1330
July	1st to 10th	Night	8% 4 1 5% 4 3 4 4 6% 11% 51%	2418
	11th to 20th	Night	8% 5% 1 5% 3 3 3 4 6% 9% 53%	2746
	21st to end	Night	6% 4 1 6% 4 5% 4 5% 7% 10% 49%	3087
August	1st to 10th	Night	12% 6% 1 6% 4 4 4 4 6% 8% 44%	2825
	11th to 20th	Night	7% 4 2 7% 4 4 5% 4 6% 8% 49%	2785
	21st to end	Night	8% 5% 2 6% 5% 5% 4 4 6% 8% 48%	3124
September	1st to 10th	Night	10% 6% 3 5% 4 4 4 3 5% 8% 46%	1998
	11th to 20th	Night	10% 5% 2 5% 4 3 3 3 5% 7% 54%	2090
	21st to end	Night	16% 6% 3 7% 4 4 4 4 5% 6% 40%	2090
October	1st to 10th	Night	15% 5% 2 6% 3 4 4 3 5% 7% 45%	2209
	11th to 20th	Night	18% 7% 3 8% 4 4 4 4 5% 7% 36%	2280
	21st to end	Night	22% 8% 3 7% 6% 5% 4 3 5% 7% 32%	2558
November	1st to 10th	Night	14% 7% 2 7% 4 4 3 4 6% 6% 42%	2536
	11th to 20th	Night	17% 10% 3 8% 5% 5% 5% 4 5% 7% 30%	2665
	21st to end	Night	21% 13% 4 8% 5% 4 4 3 5% 6% 26%	2800
December	1st to 10th	Night	17% 13% 4 9% 5% 5% 5% 4 6% 7% 23%	4580
	11th to 20th	Night	19% 17% 5% 11% 6% 4 5% 4 4 5% 20%	5205
	21st to end	Night	25% 19% 6% 11% 6% 5% 4 3 4 5% 13%	6925

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	67% 11% 6% 10% 5% 1	3771
	11th to 20th	Day	78% 8% 7% 5% 2	4060
	21st to end	Day	72% 6% 10% 9% 3	4466
February	1st to 10th	Day	62% 7% 10% 15% 5% 1	1800
	11th to 20th	Day	59% 6% 10% 16% 7% 1	1812
	21st to end	Day	55% 7% 13% 18% 6% 2	1570
March	1st to 10th	Day	56% 7% 10% 22% 5%	3312
	11th to 20th	Day	47% 7% 17% 20% 8% 1	3480
	21st to end	Day	48% 7% 13% 21% 10% 2	3815
April	1st to 10th	Day	45% 7% 14% 20% 13% 1	2133
	11th to 20th	Day	46% 7% 12% 20% 14% 1	2442
	21st to end	Day	48% 6% 12% 21% 10% 3	2470
May	1st to 10th	Day	46% 8% 11% 23% 11% 2	4120
	11th to 20th	Day	44% 11% 16% 20% 8% 1	4085
	21st to end	Day	33% 9% 13% 21% 17% 8%	4649
June	1st to 10th	Day	37% 8% 15% 25% 14% 2	2660
	11th to 20th	Day	34% 8% 15% 23% 17% 2	2829
	21st to end	Day	32% 8% 15% 26% 16% 2	2850
July	1st to 10th	Day	33% 7% 13% 27% 17% 3	4478
	11th to 20th	Day	27% 6% 16% 33% 16% 1	4128
	21st to end	Day	32% 8% 18% 21% 19% 3	4324
August	1st to 10th	Day	35% 7% 16% 26% 14% 1	4091
	11th to 20th	Day	34% 8% 16% 32% 8% 1	4083
	21st to end	Day	33% 8% 15% 30% 13% 2	4505
September	1st to 10th	Day	35% 7% 16% 25% 14% 2	2174
	11th to 20th	Day	30% 8% 16% 28% 16% 1	2090
	21st to end	Day	44% 8% 12% 23% 13% 1	2090
October	1st to 10th	Day	31% 7% 15% 27% 20% 1	3270
	11th to 20th	Day	42% 5% 13% 21% 17%	3140
	21st to end	Day	44% 7% 15% 25% 9%	3340
November	1st to 10th	Day	48% 7% 12% 21% 10% 2	1762
	11th to 20th	Day	55% 8% 13% 15% 9% 1	1732
	21st to end	Day	65% 9% 9% 13% 4	1600
December	1st to 10th	Day	66% 10% 11% 10% 3	2600
	11th to 20th	Day	71% 6% 12% 8% 4	2986
	21st to end	Day	76% 6% 8% 8% 1	3967
January	1st to 10th	Night	61% 10% 9% 13% 5% 2	6142
	11th to 20th	Night	69% 12% 8% 8% 3 1	5900
	21st to end	Night	67% 6% 9% 12% 7%	6490
February	1st to 10th	Night	63% 6% 10% 15% 5% 1	2600
	11th to 20th	Night	59% 6% 10% 17% 8% 1	2481
	21st to end	Night	57% 6% 10% 18% 8% 1	1885
March	1st to 10th	Night	54% 5% 13% 20% 8%	3541
	11th to 20th	Night	41% 8% 15% 19% 15% 1	3480
	21st to end	Night	46% 7% 9% 20% 16% 1	3817
April	1st to 10th	Night	50% 5% 11% 19% 13% 2	2054
	11th to 20th	Night	47% 6% 10% 21% 14% 2	1692
	21st to end	Night	46% 6% 9% 20% 15% 4	1710
May	1st to 10th	Night	47% 7% 8% 19% 14% 4	2840
	11th to 20th	Night	46% 9% 10% 21% 12% 2	2813
	21st to end	Night	32% 8% 11% 24% 23% 3	2909
June	1st to 10th	Night	36% 8% 11% 26% 16% 4	1520
	11th to 20th	Night	34% 8% 13% 24% 18% 3	1344
	21st to end	Night	35% 7% 11% 26% 20% 1	1330
July	1st to 10th	Night	28% 6% 11% 28% 20% 6%	2378
	11th to 20th	Night	28% 6% 14% 30% 21% 2	2696
	21st to end	Night	29% 9% 16% 22% 22% 3	2988
August	1st to 10th	Night	37% 8% 12% 26% 15% 2	2814
	11th to 20th	Night	32% 9% 12% 31% 15% 1	2812
	21st to end	Night	33% 7% 12% 30% 17% 1	3124
September	1st to 10th	Night	36% 7% 12% 26% 17% 3	1998
	11th to 20th	Night	31% 7% 10% 30% 20% 2	2090
	21st to end	Night	45% 7% 10% 24% 13% 1	2090
October	1st to 10th	Night	28% 6% 8% 28% 28% 1	3690
	11th to 20th	Night	46% 6% 10% 21% 17%	3779
	21st to end	Night	40% 6% 15% 25% 13% 1	4206
November	1st to 10th	Night	46% 7% 10% 22% 14% 1	2536
	11th to 20th	Night	55% 10% 9% 16% 9% 1	2665
	21st to end	Night	61% 8% 11% 15% 5%	2800
December	1st to 10th	Night	63% 10% 14% 11% 2	4580
	11th to 20th	Night	67% 7% 11% 10% 4	5208
	21st to end	Night	74% 7% 9% 7% 2	6925

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	22% 10% 37% 22% 9% 1	300
	11th to 20th	Day	24% 13% 40% 17% 5% 1	300
	21st to end	Day	26% 11% 31% 27% 5% 1	330
February	1st to 10th	Day	19% 11% 36% 28% 5% 1	300
	11th to 20th	Day	21% 12% 33% 31% 3	300
	21st to end	Day	21% 11% 38% 26% 4	225
March	1st to 10th	Day	18% 11% 30% 33% 9% 1	384
	11th to 20th	Day	15% 11% 29% 35% 8% 1	460
	21st to end	Day	24% 7% 28% 32% 8% 1	506
April	1st to 10th	Day	14% 7% 32% 34% 12% 1	460
	11th to 20th	Day	21% 8% 27% 31% 9% 5%	452
	21st to end	Day	18% 6% 25% 36% 13% 1	460
May	1st to 10th	Day	21% 5% 22% 32% 18% 2	463
	11th to 20th	Day	16% 2 19% 33% 25% 4	487
	21st to end	Day	12% 2 15% 31% 31% 9%	529
June	1st to 10th	Day	11% 4 14% 41% 25% 5%	490
	11th to 20th	Day	10% 1 16% 38% 30% 4	659
	21st to end	Day	12% 3 14% 40% 28% 4	680
July	1st to 10th	Day	7% 3 10% 35% 32% 12%	671
	11th to 20th	Day	12% 3 10% 36% 30% 9%	535
	21st to end	Day	8% 2 9% 34% 39% 7%	532
August	1st to 10th	Day	9% 3 10% 35% 31% 12%	486
	11th to 20th	Day	9% 5% 11% 32% 35% 9%	479
	21st to end	Day	9% 3 13% 32% 33% 11%	539
September	1st to 10th	Day	12% 4 13% 29% 29% 12%	490
	11th to 20th	Day	8% 2 11% 26% 37% 16%	490
	21st to end	Day	17% 6% 20% 27% 21% 8%	490
October	1st to 10th	Day	14% 6% 22% 26% 23% 9%	490
	11th to 20th	Day	18% 12% 25% 29% 12% 4	490
	21st to end	Day	25% 12% 27% 24% 12% 1	487
November	1st to 10th	Day	14% 12% 28% 28% 15% 3	300
	11th to 20th	Day	25% 14% 26% 26% 8% 1	265
	21st to end	Day	28% 13% 34% 23% 3	200
December	1st to 10th	Day	23% 15% 32% 24% 7%	200
	11th to 20th	Day	28% 18% 32% 21% 2	200
	21st to end	Day	29% 18% 29% 20% 4	236
January	1st to 10th	Night	25% 15% 37% 17% 5% 1	911
	11th to 20th	Night	30% 14% 30% 21% 5%	800
	21st to end	Night	24% 10% 32% 27% 7%	880
February	1st to 10th	Night	25% 8% 34% 28% 5%	800
	11th to 20th	Night	22% 10% 30% 31% 6%	783
	21st to end	Night	26% 7% 36% 27% 5%	629
March	1st to 10th	Night	21% 6% 31% 33% 9%	760
	11th to 20th	Night	17% 7% 34% 30% 10% 1	760
	21st to end	Night	20% 7% 29% 31% 11% 2	836
April	1st to 10th	Night	19% 7% 28% 35% 10% 1	760
	11th to 20th	Night	19% 6% 28% 33% 12% 2	568
	21st to end	Night	18% 5% 22% 41% 13% 2	570
May	1st to 10th	Night	17% 5% 22% 34% 20% 3	570
	11th to 20th	Night	17% 4 18% 32% 25% 4	561
	21st to end	Night	12% 1 12% 37% 32% 6%	517
June	1st to 10th	Night	12% 2 19% 40% 23% 4	380
	11th to 20th	Night	12% 1 14% 38% 32% 2	380
	21st to end	Night	9% 3 16% 41% 27% 4	380
July	1st to 10th	Night	7% 2 10% 34% 38% 9%	482
	11th to 20th	Night	11% 3 11% 36% 31% 8%	552
	21st to end	Night	7% 2 13% 36% 37% 5%	624
August	1st to 10th	Night	10% 2 10% 36% 34% 8%	567
	11th to 20th	Night	8% 3 12% 32% 37% 8%	564
	21st to end	Night	10% 3 15% 32% 34% 7%	627
September	1st to 10th	Night	12% 4 15% 27% 31% 10%	755
	11th to 20th	Night	10% 3 13% 28% 36% 10%	760
	21st to end	Night	19% 5% 17% 31% 21% 7%	760
October	1st to 10th	Night	18% 6% 21% 28% 20% 7%	760
	11th to 20th	Night	22% 11% 25% 25% 14% 2	760
	21st to end	Night	26% 12% 26% 27% 8%	836
November	1st to 10th	Night	19% 12% 26% 27% 14% 2	780
	11th to 20th	Night	26% 14% 32% 20% 7% 1	800
	21st to end	Night	29% 16% 29% 20% 7%	800
December	1st to 10th	Night	30% 16% 31% 17% 6% 1	800
	11th to 20th	Night	25% 17% 33% 21% 4	800
	21st to end	Night	31% 12% 29% 24% 3	883

Page generated at 2025-02-18 03:26:33. Version ac07

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