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 2026-06-16.

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	13% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	137799
	Night	15% 10% 4 8% 5% 5% 5% 4 5% 7% 33%	134100
Transparency	Day	46% 7% 13% 21% 11% 1	141401
	Night	50% 7% 11% 19% 12% 1	138570
Seeing	Day	15% 7% 21% 31% 20% 5%	17140
	Night	19% 8% 25% 29% 16% 3	26411

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	14% 14% 7% 17% 6% 5% 5% 4 4 5% 18%	4896
	11th to 20th	Day	12% 20% 9% 15% 9% 8% 5% 3 4 3 12%	5280
	21st to end	Day	17% 14% 5% 13% 7% 6% 6% 4 5% 5% 18%	5780
February	1st to 10th	Day	15% 16% 4 11% 7% 5% 5% 3 4 5% 24%	1890
	11th to 20th	Day	15% 10% 4 12% 8% 6% 6% 4 5% 6% 25%	1896
	21st to end	Day	16% 11% 4 11% 6% 5% 5% 4 6% 6% 26%	1730
March	1st to 10th	Day	17% 10% 4 10% 6% 5% 5% 4 5% 5% 28%	4862
	11th to 20th	Day	11% 9% 3 10% 6% 5% 5% 4 6% 8% 34%	5090
	21st to end	Day	17% 9% 4 8% 6% 6% 5% 4 6% 6% 30%	5586
April	1st to 10th	Day	16% 9% 3 7% 6% 5% 5% 3 6% 7% 32%	2359
	11th to 20th	Day	16% 8% 3 7% 5% 4 5% 4 6% 7% 34%	2702
	21st to end	Day	16% 8% 3 8% 5% 5% 5% 3 6% 7% 35%	2730
May	1st to 10th	Day	16% 10% 3 8% 4 5% 5% 4 5% 7% 34%	7616
	11th to 20th	Day	14% 8% 3 8% 5% 5% 6% 5% 6% 8% 33%	7626
	21st to end	Day	14% 5% 2 7% 5% 4 5% 4 5% 7% 42%	8690
June	1st to 10th	Day	10% 6% 2 6% 5% 4 5% 5% 7% 9% 42%	2940
	11th to 20th	Day	9% 4 3 7% 5% 5% 5% 5% 7% 9% 43%	3053
	21st to end	Day	9% 5% 2 6% 4 4 4 4 7% 11% 45%	3000
July	1st to 10th	Day	8% 5% 2 6% 5% 4 5% 4 6% 9% 48%	6509
	11th to 20th	Day	7% 5% 2 5% 4 4 5% 4 6% 9% 50%	6022
	21st to end	Day	8% 4 2 6% 5% 5% 5% 4 6% 9% 47%	6424
August	1st to 10th	Day	13% 5% 2 5% 4 3 4 4 6% 9% 45%	4234
	11th to 20th	Day	7% 5% 2 6% 4 4 6% 5% 7% 10% 43%	4174
	21st to end	Day	9% 5% 2 6% 4 4 6% 4 7% 9% 44%	4647
September	1st to 10th	Day	10% 6% 2 5% 4 5% 4 4 6% 7% 47%	2288
	11th to 20th	Day	8% 4 2 4 4 4 5% 4 6% 10% 49%	2200
	21st to end	Day	17% 6% 3 6% 4 5% 5% 3 6% 7% 40%	2200
October	1st to 10th	Day	12% 5% 2 7% 5% 5% 4 3 6% 7% 44%	2074
	11th to 20th	Day	17% 7% 3 7% 5% 5% 5% 4 6% 7% 35%	2000
	21st to end	Day	21% 8% 3 8% 5% 4 5% 4 6% 7% 30%	2145
November	1st to 10th	Day	13% 10% 3 7% 5% 4 5% 4 6% 7% 35%	1852
	11th to 20th	Day	15% 12% 3 8% 6% 4 5% 4 6% 6% 30%	1818
	21st to end	Day	18% 15% 5% 11% 5% 3 5% 4 5% 7% 21%	1680
December	1st to 10th	Day	18% 14% 5% 11% 5% 5% 5% 5% 5% 7% 21%	2680
	11th to 20th	Day	22% 18% 5% 10% 5% 4 4 4 5% 6% 15%	3070
	21st to end	Day	26% 18% 7% 11% 5% 5% 5% 3 4 5% 12%	4056
January	1st to 10th	Night	15% 15% 5% 12% 6% 5% 5% 3 5% 6% 23%	7956
	11th to 20th	Night	10% 18% 8% 15% 8% 6% 7% 4 4 4 16%	7680
	21st to end	Night	17% 14% 6% 9% 6% 5% 4 4 5% 6% 24%	8401
February	1st to 10th	Night	16% 14% 5% 11% 6% 5% 4 3 5% 5% 25%	2730
	11th to 20th	Night	16% 13% 4 10% 6% 6% 4 4 6% 6% 26%	2606
	21st to end	Night	19% 12% 4 8% 5% 4 5% 5% 5% 5% 27%	2076
March	1st to 10th	Night	17% 10% 3 8% 6% 5% 4 3 5% 6% 33%	5211
	11th to 20th	Night	10% 7% 3 7% 4 4 5% 4 7% 8% 41%	5090
	21st to end	Night	15% 10% 3 8% 4 4 4 4 5% 5% 37%	5588
April	1st to 10th	Night	17% 11% 3 7% 5% 5% 4 3 4 6% 33%	2270
	11th to 20th	Night	17% 7% 3 7% 5% 5% 4 3 5% 8% 36%	1872
	21st to end	Night	16% 7% 3 7% 5% 4 5% 4 5% 7% 38%	1890
May	1st to 10th	Night	20% 8% 3 9% 5% 5% 4 4 5% 6% 31%	5237
	11th to 20th	Night	13% 9% 3 9% 5% 5% 4 4 5% 6% 37%	5234
	21st to end	Night	15% 6% 3 6% 4 5% 5% 4 6% 7% 40%	5446
June	1st to 10th	Night	10% 6% 2 6% 5% 4 4 4 6% 8% 46%	1680
	11th to 20th	Night	10% 5% 2 5% 5% 4 4 4 8% 8% 44%	1451
	21st to end	Night	8% 5% 2 5% 5% 5% 5% 4 5% 8% 48%	1400
July	1st to 10th	Night	7% 4 1 5% 5% 4 5% 4 7% 11% 47%	3450
	11th to 20th	Night	7% 4 2 6% 4 4 4 4 7% 9% 49%	3924
	21st to end	Night	7% 4 2 6% 4 4 4 4 6% 8% 51%	4427
August	1st to 10th	Night	12% 6% 1 6% 4 4 4 4 6% 8% 45%	2915
	11th to 20th	Night	7% 4 2 7% 4 4 5% 4 6% 8% 49%	2875
	21st to end	Night	8% 5% 2 6% 4 5% 4 4 6% 8% 48%	3223
September	1st to 10th	Night	10% 6% 3 5% 4 4 5% 3 5% 8% 47%	2104
	11th to 20th	Night	9% 5% 2 5% 4 3 3 3 5% 7% 55%	2200
	21st to end	Night	16% 6% 3 7% 4 4 4 4 5% 6% 41%	2200
October	1st to 10th	Night	14% 5% 2 6% 3 3 4 3 5% 6% 46%	2325
	11th to 20th	Night	18% 7% 3 8% 4 4 4 4 5% 7% 37%	2400
	21st to end	Night	21% 8% 3 7% 6% 5% 4 3 5% 6% 33%	2693
November	1st to 10th	Night	14% 8% 3 7% 4 4 4 4 6% 6% 41%	2666
	11th to 20th	Night	17% 10% 3 8% 5% 5% 5% 4 5% 7% 31%	2798
	21st to end	Night	21% 13% 4 9% 5% 4 4 3 5% 6% 26%	2940
December	1st to 10th	Night	18% 14% 4 9% 5% 5% 5% 4 6% 7% 23%	4720
	11th to 20th	Night	19% 17% 5% 11% 6% 4 4 4 4 5% 21%	5345
	21st to end	Night	25% 19% 6% 11% 5% 5% 4 3 4 5% 13%	7077

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% 9% 8% 11% 4 1	4897
	11th to 20th	Day	78% 6% 6% 5% 4	5280
	21st to end	Day	67% 5% 11% 12% 5%	5780
February	1st to 10th	Day	62% 7% 10% 16% 5% 1	1890
	11th to 20th	Day	59% 6% 11% 16% 7% 1	1905
	21st to end	Day	56% 7% 13% 17% 6% 2	1730
March	1st to 10th	Day	54% 7% 12% 20% 7%	4862
	11th to 20th	Day	45% 7% 16% 23% 8% 1	5090
	21st to end	Day	50% 7% 13% 20% 9% 1	5586
April	1st to 10th	Day	47% 7% 14% 19% 12% 1	2359
	11th to 20th	Day	46% 7% 12% 20% 13% 1	2702
	21st to end	Day	47% 6% 12% 22% 11% 3	2730
May	1st to 10th	Day	48% 7% 11% 21% 11% 2	7651
	11th to 20th	Day	43% 10% 13% 23% 9% 2	7630
	21st to end	Day	40% 7% 11% 20% 17% 5%	8705
June	1st to 10th	Day	36% 7% 14% 25% 16% 2	2940
	11th to 20th	Day	34% 8% 16% 24% 16% 2	3053
	21st to end	Day	32% 8% 15% 26% 17% 2	3000
July	1st to 10th	Day	31% 7% 12% 31% 17% 2	6440
	11th to 20th	Day	29% 6% 16% 30% 17% 1	5950
	21st to end	Day	32% 7% 16% 24% 19% 2	6240
August	1st to 10th	Day	35% 7% 17% 26% 15%	4221
	11th to 20th	Day	34% 8% 16% 33% 8% 1	4213
	21st to end	Day	33% 7% 15% 30% 13% 1	4647
September	1st to 10th	Day	35% 7% 16% 27% 14% 2	2288
	11th to 20th	Day	29% 8% 16% 30% 16% 1	2200
	21st to end	Day	44% 8% 12% 23% 13% 1	2200
October	1st to 10th	Day	30% 7% 14% 28% 20% 1	3373
	11th to 20th	Day	42% 5% 13% 22% 17%	3240
	21st to end	Day	44% 7% 15% 24% 10%	3447
November	1st to 10th	Day	49% 7% 11% 21% 10% 2	1852
	11th to 20th	Day	54% 8% 13% 15% 9% 1	1818
	21st to end	Day	64% 9% 9% 14% 4	1680
December	1st to 10th	Day	66% 9% 11% 10% 3	2680
	11th to 20th	Day	71% 6% 12% 8% 4	3066
	21st to end	Day	76% 6% 8% 8% 1	4056
January	1st to 10th	Night	62% 9% 9% 12% 6% 1	7957
	11th to 20th	Night	68% 10% 8% 9% 5% 1	7680
	21st to end	Night	62% 6% 9% 16% 7%	8401
February	1st to 10th	Night	62% 6% 10% 16% 5% 1	2730
	11th to 20th	Night	59% 6% 10% 17% 8% 1	2608
	21st to end	Night	57% 6% 10% 18% 8% 1	2076
March	1st to 10th	Night	52% 5% 13% 19% 11% 1	5211
	11th to 20th	Night	39% 7% 15% 25% 14% 1	5090
	21st to end	Night	48% 6% 9% 18% 17% 1	5588
April	1st to 10th	Night	52% 5% 10% 18% 12% 2	2270
	11th to 20th	Night	46% 6% 10% 21% 14% 2	1872
	21st to end	Night	45% 5% 10% 22% 14% 3	1890
May	1st to 10th	Night	52% 6% 9% 14% 14% 5%	5264
	11th to 20th	Night	46% 7% 9% 24% 12% 3	5235
	21st to end	Night	42% 6% 10% 21% 19% 2	5453
June	1st to 10th	Night	36% 7% 10% 25% 18% 5%	1680
	11th to 20th	Night	34% 7% 14% 24% 18% 3	1451
	21st to end	Night	35% 7% 11% 25% 21% 1	1400
July	1st to 10th	Night	30% 7% 15% 26% 18% 4	3412
	11th to 20th	Night	31% 7% 14% 28% 19% 2	3877
	21st to end	Night	30% 7% 13% 21% 26% 3	4297
August	1st to 10th	Night	36% 8% 12% 26% 16% 2	2904
	11th to 20th	Night	32% 9% 11% 31% 15% 1	2902
	21st to end	Night	33% 7% 12% 31% 17% 1	3223
September	1st to 10th	Night	35% 7% 12% 28% 16% 3	2104
	11th to 20th	Night	30% 7% 11% 32% 19% 2	2200
	21st to end	Night	45% 7% 10% 24% 14% 1	2200
October	1st to 10th	Night	28% 6% 8% 29% 28% 1	3806
	11th to 20th	Night	46% 6% 10% 21% 17%	3899
	21st to end	Night	40% 6% 15% 25% 14% 1	4341
November	1st to 10th	Night	46% 7% 10% 22% 14% 1	2666
	11th to 20th	Night	55% 10% 9% 16% 9% 1	2798
	21st to end	Night	62% 7% 11% 14% 5%	2940
December	1st to 10th	Night	63% 10% 14% 11% 2	4720
	11th to 20th	Night	67% 7% 11% 11% 4	5348
	21st to end	Night	74% 7% 9% 7% 2	7077

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% 23% 8% 1	330
	11th to 20th	Day	22% 16% 40% 16% 4 1	330
	21st to end	Day	25% 11% 32% 27% 5% 1	363
February	1st to 10th	Day	18% 11% 34% 28% 7% 2	330
	11th to 20th	Day	20% 12% 32% 31% 5% 1	330
	21st to end	Day	19% 12% 37% 28% 4	273
March	1st to 10th	Day	18% 10% 30% 33% 8%	456
	11th to 20th	Day	15% 11% 31% 34% 7% 1	540
	21st to end	Day	22% 7% 28% 33% 8% 1	594
April	1st to 10th	Day	17% 7% 31% 33% 11% 1	540
	11th to 20th	Day	20% 8% 28% 30% 10% 5%	532
	21st to end	Day	17% 5% 25% 36% 16% 1	540
May	1st to 10th	Day	22% 5% 21% 33% 17% 2	543
	11th to 20th	Day	16% 2 19% 34% 26% 4	567
	21st to end	Day	13% 2 15% 32% 30% 8%	617
June	1st to 10th	Day	10% 4 13% 40% 27% 5%	570
	11th to 20th	Day	10% 2 17% 38% 29% 4	733
	21st to end	Day	11% 3 13% 39% 30% 5%	730
July	1st to 10th	Day	8% 3 10% 35% 32% 12%	721
	11th to 20th	Day	11% 3 10% 36% 30% 9%	578
	21st to end	Day	8% 2 9% 33% 41% 7%	576
August	1st to 10th	Day	8% 2 9% 34% 34% 13%	526
	11th to 20th	Day	9% 5% 10% 31% 36% 9%	519
	21st to end	Day	8% 3 13% 31% 34% 10%	583
September	1st to 10th	Day	12% 5% 13% 28% 30% 13%	530
	11th to 20th	Day	7% 2 11% 25% 39% 17%	530
	21st to end	Day	17% 6% 18% 27% 22% 10%	530
October	1st to 10th	Day	13% 6% 21% 26% 24% 10%	530
	11th to 20th	Day	17% 12% 25% 31% 13% 3	530
	21st to end	Day	24% 12% 27% 24% 12% 1	528
November	1st to 10th	Day	17% 12% 28% 27% 14% 2	330
	11th to 20th	Day	23% 15% 27% 25% 8% 1	291
	21st to end	Day	26% 14% 34% 22% 4	220
December	1st to 10th	Day	22% 15% 33% 24% 6%	220
	11th to 20th	Day	29% 18% 31% 20% 2	220
	21st to end	Day	30% 18% 28% 20% 3	260
January	1st to 10th	Night	25% 15% 36% 18% 5% 1	956
	11th to 20th	Night	29% 15% 30% 21% 5%	840
	21st to end	Night	23% 10% 33% 27% 6%	924
February	1st to 10th	Night	24% 8% 33% 29% 6%	840
	11th to 20th	Night	22% 10% 30% 31% 6%	823
	21st to end	Night	25% 7% 36% 27% 5%	692
March	1st to 10th	Night	20% 7% 32% 32% 9%	840
	11th to 20th	Night	17% 8% 34% 30% 10% 1	840
	21st to end	Night	20% 7% 30% 31% 10% 2	924
April	1st to 10th	Night	21% 8% 28% 33% 9% 1	840
	11th to 20th	Night	18% 6% 28% 34% 12% 2	628
	21st to end	Night	17% 5% 23% 40% 13% 2	630
May	1st to 10th	Night	18% 5% 23% 33% 18% 3	630
	11th to 20th	Night	17% 4 20% 33% 23% 4	621
	21st to end	Night	13% 1 13% 38% 30% 6%	573
June	1st to 10th	Night	11% 3 18% 41% 24% 4	420
	11th to 20th	Night	13% 1 14% 39% 31% 2	410
	21st to end	Night	9% 3 16% 39% 29% 4	400
July	1st to 10th	Night	7% 2 9% 34% 39% 9%	508
	11th to 20th	Night	11% 3 11% 35% 32% 8%	582
	21st to end	Night	8% 2 12% 36% 37% 5%	657
August	1st to 10th	Night	10% 2 9% 36% 35% 8%	597
	11th to 20th	Night	7% 3 12% 31% 38% 8%	594
	21st to end	Night	10% 3 14% 32% 34% 7%	660
September	1st to 10th	Night	12% 4 15% 27% 32% 11%	795
	11th to 20th	Night	10% 3 12% 26% 38% 11%	800
	21st to end	Night	19% 5% 16% 31% 22% 7%	800
October	1st to 10th	Night	18% 6% 20% 28% 21% 7%	800
	11th to 20th	Night	22% 11% 26% 26% 14% 2	800
	21st to end	Night	26% 12% 26% 28% 8%	880
November	1st to 10th	Night	19% 12% 26% 27% 14% 2	820
	11th to 20th	Night	25% 15% 31% 21% 7% 1	840
	21st to end	Night	29% 16% 28% 20% 7%	840
December	1st to 10th	Night	30% 16% 31% 17% 6% 1	840
	11th to 20th	Night	25% 17% 33% 21% 4	840
	21st to end	Night	31% 12% 30% 24% 3	927

Page generated at 2026-06-13 02:31:44. Version ac07

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